home *** CD-ROM | disk | FTP | other *** search
Text File | 1988-03-16 | 85.6 KB | 3,279 lines
O✓O✓O✓Ob✓b✓b✓bj✓j✓j✓je✓e✓e✓ec✓c✓c✓ct✓t✓t✓t The class O✓O✓O✓Ob✓b✓b✓bj✓j✓j✓je✓e✓e✓ec✓c✓c✓ct✓t✓t✓t is a superclass of all classes in the system, and is used to provide a consistent basic func- tionality and default behavior. Many methods in class O✓O✓O✓Ob✓b✓b✓bj✓j✓j✓je✓e✓e✓ec✓c✓c✓ct✓t✓t✓t are overridden in subclasses. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓t_✓o == Return true if receiver and argument are the same object, false otherwise. ~~ Inverse of ==. asString Return a string representation of the receiver, by default this is the same as _✓p_✓r_✓i_✓n_✓t_✓S_✓t_✓r_✓i_✓n_✓g, although one or the other is redefined in many subclasses. asSymbol Return a symbol representing the receiver. class Return object representing the class of the receiver. copy Return shallowCopy of receiver. Many subc- lasses redefine shallowCopy. deepCopy Return the receiver. This method is rede- fined in many subclasses. _✓d do: The argument must be a one argument block. Execute the block on every element of the receiver collection. Elements in the receiver collection are listed using _✓f_✓i_✓r_✓s_✓t and _✓n_✓e_✓x_✓t (below), so the default behavior is merely to execute the block using the receiver as argument. error: Argument must be a String. Print argument string as error message. Return n✓n✓n✓ni✓i✓i✓il✓l✓l✓l. _✓n first Return first item in sequence, which is by default simply the receiver. See _✓n_✓e_✓x_✓t, below. isKindOf: Argument must be a C✓C✓C✓Cl✓l✓l✓la✓a✓a✓as✓s✓s✓ss✓s✓s✓s. Return true if class of receiver, or any superclass thereof, is the same as argument. isMemberOf: Argument must be a C✓C✓C✓Cl✓l✓l✓la✓a✓a✓as✓s✓s✓ss✓s✓s✓s. Return true if receiver is instance of argument class. class O✓O✓O✓Ob✓b✓b✓bj✓j✓j✓je✓e✓e✓ec✓c✓c✓ct✓t✓t✓t (continued) isNil Test whether receiver is object n✓n✓n✓ni✓i✓i✓il✓l✓l✓l. _✓n next Return next item in sequence, which is by default n✓n✓n✓ni✓i✓i✓il✓l✓l✓l. This message is redefined in classes which represent sequences, such as A✓A✓A✓Ar✓r✓r✓rr✓r✓r✓ra✓a✓a✓ay✓y✓y✓y or D✓D✓D✓Di✓i✓i✓ic✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓na✓a✓a✓ar✓r✓r✓ry✓y✓y✓y. notNil Test if receiver is not object n✓n✓n✓ni✓i✓i✓il✓l✓l✓l. print Display print image of receiver on the stan- dard output. printString Return a string representation of receiver. Objects which do not redefine printString, and which therefore do not have a printable representation, return their class name as a string. respondsTo: Argument must be a symbol. Return true if receiver will respond to the indicated mes- sage. shallowCopy Return the receiver. This method is rede- fined in many subclasses. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result 7 ~~ 7.0 True 7 asSymbol #7 7 class Integer 7 copy 7 7 isKindOf: Number True 7 isMemberOf: Number False 7 isNil False 7 respondsTo: #+ True Object U✓U✓U✓Un✓n✓n✓nd✓d✓d✓de✓e✓e✓ef✓f✓f✓fi✓i✓i✓in✓n✓n✓ne✓e✓e✓ed✓d✓d✓dO✓O✓O✓Ob✓b✓b✓bj✓j✓j✓je✓e✓e✓ec✓c✓c✓ct✓t✓t✓t The pseudo variable n✓n✓n✓ni✓i✓i✓il✓l✓l✓l is an instance (usually the only instance) of the class U✓U✓U✓Un✓n✓n✓nd✓d✓d✓de✓e✓e✓ef✓f✓f✓fi✓i✓i✓in✓n✓n✓ne✓e✓e✓ed✓d✓d✓dO✓O✓O✓Ob✓b✓b✓bj✓j✓j✓je✓e✓e✓ec✓c✓c✓ct✓t✓t✓t. n✓n✓n✓ni✓i✓i✓il✓l✓l✓l is used to represent undefined values, and is also typically returned in error situations. n✓n✓n✓ni✓i✓i✓il✓l✓l✓l is also used as a terminator in sequences, as for example in response to the message _✓n_✓e_✓x_✓t when there are no further elements in a sequence. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓t_✓o _✓r isNil Overrides method found in Object. Return true. _✓r notNil Overrides method found in Object. Return false. _✓r printString Return 'nil'. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result nil isNil True Object S✓S✓S✓Sy✓y✓y✓ym✓m✓m✓mb✓b✓b✓bo✓o✓o✓ol✓l✓l✓l Instances of the class S✓S✓S✓Sy✓y✓y✓ym✓m✓m✓mb✓b✓b✓bo✓o✓o✓ol✓l✓l✓l are created either by their literal representation, which is a pound sign followed by a string of nonspace characters (for example #aSymbol ), or by the message _✓a_✓s_✓S_✓y_✓m_✓b_✓o_✓l being passed to an object. Sym- bols cannot be created using _✓n_✓e_✓w. Symbols are guaranteed to have unique representations; that is, two symbols represent- ing the same characters will always test equal to each other. Inside of literal arrays, the leading pound signs on symbols can be eliminated, for example: #(these are sym- bols). _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓t_✓o _✓r == Return true if the two symbols represent the same characters, false otherwise. _✓r asString Return a String representation of the symbol without the leading pound sign. _✓r printString Return a String representation of the symbol, including the leading pound sign. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result #abc == #abc True #abc == #ABC False #abc ~~ #ABC True #abc printString #abc 'abc' asSymbol #abc Object B✓B✓B✓Bo✓o✓o✓oo✓o✓o✓ol✓l✓l✓le✓e✓e✓ea✓a✓a✓an✓n✓n✓n The class B✓B✓B✓Bo✓o✓o✓oo✓o✓o✓ol✓l✓l✓le✓e✓e✓ea✓a✓a✓an✓n✓n✓n provides protocol for manipulating true and false values. The pseudo variables t✓t✓t✓tr✓r✓r✓ru✓u✓u✓ue✓e✓e✓e and f✓f✓f✓fa✓a✓a✓al✓l✓l✓ls✓s✓s✓se✓e✓e✓e are instances of the subclasses of B✓B✓B✓Bo✓o✓o✓oo✓o✓o✓ol✓l✓l✓le✓e✓e✓ea✓a✓a✓an✓n✓n✓n; T✓T✓T✓Tr✓r✓r✓ru✓u✓u✓ue✓e✓e✓e and F✓F✓F✓Fa✓a✓a✓al✓l✓l✓ls✓s✓s✓se✓e✓e✓e, respectively. The subclasses T✓T✓T✓Tr✓r✓r✓ru✓u✓u✓ue✓e✓e✓e and F✓F✓F✓Fa✓a✓a✓al✓l✓l✓ls✓s✓s✓se✓e✓e✓e, in combination with blocks, are used to implement conditional control structures. Note, however, that the bytecodes may optimize conditional tests by generating code in-line, rather than using message passing. Note that bit-wise boolean opera- tions are provided by class I✓I✓I✓In✓n✓n✓nt✓t✓t✓te✓e✓e✓eg✓g✓g✓ge✓e✓e✓er✓r✓r✓r. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓T_✓o & The argument must be a boolean. Return the logical conjunction (and) of the two values. | The argument must be a boolean. Return the logical disjunction (or) of the two values. and: The argument must be a block. Return the logical conjunction (and) of the two values. If the receiver is false the second argument is not used, otherwise the result is the value yielded in evaluating the argument block. or: The argument must be a block. Return the logical disjunction (or) of the two values. If the receiver is true the second argument is not used, otherwise the result is the value yielded in evaluating the argument block. eqv: The argument must be a boolean. Return the logical equivalence (eqv) of the two values. xor: The argument must be a boolean. Return the logical exclusive or (xor) of the two values. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result (1 > 3) & (2 < 4) False (1 > 3) | (2 < 4) True (1 > 3) and: [2 < 4] False Object Boolean T✓T✓T✓Tr✓r✓r✓ru✓u✓u✓ue✓e✓e✓e The pseudo variable t✓t✓t✓tr✓r✓r✓ru✓u✓u✓ue✓e✓e✓e is an instance (usually the only instance) of the class T✓T✓T✓Tr✓r✓r✓ru✓u✓u✓ue✓e✓e✓e. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓T_✓o ifTrue: Return the result of evaluating the argument block. ifFalse: Return n✓n✓n✓ni✓i✓i✓il✓l✓l✓l. ifTrue:ifFalse: Return the result of evaluating the first argument block. ifFalse:ifTrue: Return the result of evaluating the second argument block. not Return f✓f✓f✓fa✓a✓a✓al✓l✓l✓ls✓s✓s✓se✓e✓e✓e. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result (3 < 5) not False (3 < 5) ifTrue: [17] 17 Object Boolean F✓F✓F✓Fa✓a✓a✓al✓l✓l✓ls✓s✓s✓se✓e✓e✓e The pseudo variable f✓f✓f✓fa✓a✓a✓al✓l✓l✓ls✓s✓s✓se✓e✓e✓e is an instance (usually the only instance) of the class F✓F✓F✓Fa✓a✓a✓al✓l✓l✓ls✓s✓s✓se✓e✓e✓e. ifTrue: Return n✓n✓n✓ni✓i✓i✓il✓l✓l✓l. ifFalse: Return the result of evaluating the argument block. ifTrue:ifFalse: Return the result of evaluating the second argument block. ifFalse:ifTrue: Return the result of evaluating the first argument block. not Return t✓t✓t✓tr✓r✓r✓ru✓u✓u✓ue✓e✓e✓e. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result (1 < 3) ifTrue: [17] 17 (1 < 3) ifFalse: [17] nil Object M✓M✓M✓Ma✓a✓a✓ag✓g✓g✓gn✓n✓n✓ni✓i✓i✓it✓t✓t✓tu✓u✓u✓ud✓d✓d✓de✓e✓e✓e The class M✓M✓M✓Ma✓a✓a✓ag✓g✓g✓gn✓n✓n✓ni✓i✓i✓it✓t✓t✓tu✓u✓u✓ud✓d✓d✓de✓e✓e✓e provides protocol for those subc- lasses possessing a linear ordering. For the sake of effi- ciency, most subclasses redefine some or all of the rela- tional messages. All methods are defined in terms of the basic messages <, = and >, which are in turn defined circu- larly in terms of each other. Thus each subclass of M✓M✓M✓Ma✓a✓a✓ag✓g✓g✓gn✓n✓n✓ni✓i✓i✓i-✓-✓-✓- t✓t✓t✓tu✓u✓u✓ud✓d✓d✓de✓e✓e✓e must redefine at least one of these messages. < Relational less than test. Returns a boolean. <= Relational less than or equal test. = Relational equal test. Note that this differs from ==, which is an object equality test. ~= Relational not equal test, opposite of =. >= Relational greater than or equal test. > Relational greater than test. between:and: Relational test for inclusion. max: Return the maximum of the receiver and argu- ment value. min: Return the minimum of the receiver and argu- ment value. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result $A max: $a $a 4 between: 3.1 and: (17/3) True Object Magnitude C✓C✓C✓Ch✓h✓h✓ha✓a✓a✓ar✓r✓r✓r This class defines protocol for objects with character values. Characters possess an ordering given by the under- lying representation, however arithmetic is not defined for character values. Characters are written literally by preceding the character desired with a dollar sign, for example: $a $B $$. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓t_✓o _✓r == Object equality test. Two instances of the same character always test equal. asciiValue Return an I✓I✓I✓In✓n✓n✓nt✓t✓t✓te✓e✓e✓eg✓g✓g✓ge✓e✓e✓er✓r✓r✓r representing the ascii value of the receiver. asLowercase If the receiver is an uppercase letter returns the same letter in lowercase, other- wise returns the receiver. asUppercase If the receiver is a lowercase letter returns the same letter in uppercase, otherwise returns the receiver. _✓r asString Return a length one string containing the receiver. Does not contain leading dollar sign, compare to _✓p_✓r_✓i_✓n_✓t_✓S_✓t_✓r_✓i_✓n_✓g. digitValue If the receiver represents a number (for example $9) return the digit value of the number. If the receiver is an uppercase letter (for example $B) return the position of the number in the uppercase letters + 10, ($B returns 11, for example). If the receiver is neither a digit nor an uppercase letter an error is given and n✓n✓n✓ni✓i✓i✓il✓l✓l✓l returned. isAlphaNumericRespond true if receiver is either digit or letter, false otherwise. isDigit Respond true if receiver is a digit, false otherwise. isLetter Respond true if receiver is a letter, false otherwise. isLowercase Respond true if receiver is a lowercase letter, false otherwise. isSeparator Respond true if receiver is a space, tab or class C✓C✓C✓Ch✓h✓h✓ha✓a✓a✓ar✓r✓r✓r (continued) newline, false otherwise. isUppercase Respond true if receiver is an uppercase letter, false otherwise. isVowel Respond true if receiver is $a, $e, $i, $o or $u, in either upper or lower case. _✓r printString Respond with a string representation of the character value. Includes leading dollar sign, compare to _✓a_✓s_✓S_✓t_✓r_✓i_✓n_✓g, which does not include $. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result $A < $0 False $A asciiValue 65 $A asString A $A printString $A $A isVowel True $A digitValue 10 Object Magnitude N✓N✓N✓Nu✓u✓u✓um✓m✓m✓mb✓b✓b✓be✓e✓e✓er✓r✓r✓r The class N✓N✓N✓Nu✓u✓u✓um✓m✓m✓mb✓b✓b✓be✓e✓e✓er✓r✓r✓r is an abstract superclass for I✓I✓I✓In✓n✓n✓nt✓t✓t✓te✓e✓e✓eg✓g✓g✓ge✓e✓e✓er✓r✓r✓r and F✓F✓F✓Fl✓l✓l✓lo✓o✓o✓oa✓a✓a✓at✓t✓t✓t. Instances of N✓N✓N✓Nu✓u✓u✓um✓m✓m✓mb✓b✓b✓be✓e✓e✓er✓r✓r✓r cannot be created directly. Relational messages and many arithmetic messages are rede- fined in each subclass for arguments of the appropriate type. In general, an error message is given and n✓n✓n✓ni✓i✓i✓il✓l✓l✓l returned for illegal arguments. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓T_✓o + Mixed type addition. - Mixed type subtraction. * Mixed type multiplication / Mixed type division. _✓n |✓^ Exponentiation, same as raisedTo: . @ Construct a point with coordinates being the receiver and the argument. abs Absolute value of the receiver. exp e raised to the power. _✓n gamma Return the gamma function (generalized fac- torial) evaluated at the receiver. ln Natural logarithm of the receiver. log: Logarithm in the given base. negated The arithmetic inverse of the receiver. negative True if the receiver is negative. _✓n pi Return the approximate value of the receiver multiplied by (3.1415926...). positive True if the receiver is positive. _✓n radians Argument converted into radians. raisedTo: The receiver raised to the argument value. reciprocal The arithmetic reciprocal of the receiver. roundTo: The receiver rounded to units of the argu- class N✓N✓N✓Nu✓u✓u✓um✓m✓m✓mb✓b✓b✓be✓e✓e✓er✓r✓r✓r (continued) ment. sign Return -1, 0 or 1 depending upon whether the receiver is negative, zero or positive. sqrt Square root. nil if receiver is less than zero. squared Return the receiver multiplied by itself. strictlyPositive True if the receiver is greater than zero. to: Interval from receiver to argument value with step of 1. to:by: Interval from receiver to argument in given steps. truncatedTo: The receiver truncated to units of the argu- ment. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result 3 < 4.1 True 3 + 4.1 7.1 3.14159 exp 23.1406 9 gamma 40320 5 reciprocal 0.2 0.5 radians 0.5 radians 13 roundTo: 5 15 13 truncateTo: 5 10 Object Magnitude Number I✓I✓I✓In✓n✓n✓nt✓t✓t✓te✓e✓e✓eg✓g✓g✓ge✓e✓e✓er✓r✓r✓r The class I✓I✓I✓In✓n✓n✓nt✓t✓t✓te✓e✓e✓eg✓g✓g✓ge✓e✓e✓er✓r✓r✓r provides protocol for objects with integer values. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓T_✓o _✓r == Object equality test. Two integers representing the same value are considered to be the same object. // Integer quotient, truncated towards negative infinity (compare to _✓q_✓u_✓o:). \\ Integer remainder, truncated towards negative infinity (compare to _✓r_✓e_✓m:). allMask: Argument must be I✓I✓I✓In✓n✓n✓nt✓t✓t✓te✓e✓e✓eg✓g✓g✓ge✓e✓e✓er✓r✓r✓r. Treating receiver and argument as bit strings, return t✓t✓t✓tr✓r✓r✓ru✓u✓u✓ue✓e✓e✓e if all bits with 1 value in argument correspond to bits with 1 values in the receiver. anyMask: Argument must be I✓I✓I✓In✓n✓n✓nt✓t✓t✓te✓e✓e✓eg✓g✓g✓ge✓e✓e✓er✓r✓r✓r. Treating receiver and argument as bit strings, return true if any bit with 1 value in argument corresponds to a bit with 1 value in the receiver. asCharacter Return the Char with the same underlying ascii representation as the low order eight bits of the receiver. asFloat Floating point value with same magnitude as receiver. bitAnd: Argument must be I✓I✓I✓In✓n✓n✓nt✓t✓t✓te✓e✓e✓eg✓g✓g✓ge✓e✓e✓er✓r✓r✓r. Treating the receiver and argument as bit strings, return logical a✓a✓a✓an✓n✓n✓nd✓d✓d✓d of values. bitAt: Argument must be I✓I✓I✓In✓n✓n✓nt✓t✓t✓te✓e✓e✓eg✓g✓g✓ge✓e✓e✓er✓r✓r✓r greater than 0 and less than underlying word size. Treating receiver as a bit string, return the bit value at the given position, numbering from low order (or rightmost) position. bitInvert Return the receiver with all bit positions inverted. bitOr: Return logical o✓o✓o✓or✓r✓r✓r of values. bitShift: Treating the receiver as a bit string, shift bit values by amount indicated in argument. class I✓I✓I✓In✓n✓n✓nt✓t✓t✓te✓e✓e✓eg✓g✓g✓ge✓e✓e✓er✓r✓r✓r (continued) Negative values shift right, positive left. bitXor: Return logical e✓e✓e✓ex✓x✓x✓xc✓c✓c✓cl✓l✓l✓lu✓u✓u✓us✓s✓s✓si✓i✓i✓iv✓v✓v✓ve✓e✓e✓e-✓-✓-✓-o✓o✓o✓or✓r✓r✓r of values. even Return true if receiver is even, false other- wise. factorial Return the factorial of the receiver. Return as Float for large numbers. gcd: Argument must be I✓I✓I✓In✓n✓n✓nt✓t✓t✓te✓e✓e✓eg✓g✓g✓ge✓e✓e✓er✓r✓r✓r. Return the greatest common divisor of the receiver and argument. highBit Return the location of the highest 1 bit in the receiver. Return n✓n✓n✓ni✓i✓i✓il✓l✓l✓l for receiver zero. lcm: Argument must be I✓I✓I✓In✓n✓n✓nt✓t✓t✓te✓e✓e✓eg✓g✓g✓ge✓e✓e✓er✓r✓r✓r. Return least com- mon multiple of receiver and argument. noMask: Argument must be I✓I✓I✓In✓n✓n✓nt✓t✓t✓te✓e✓e✓eg✓g✓g✓ge✓e✓e✓er✓r✓r✓r. Treating receiver and argument as bit strings, return true if no 1 bit in the argument corresponds to a 1 bit in the receiver. odd Return true if receiver is odd, false other- wise. quo: Return quotient of receiver divided by argu- ment. radix: Return a string representation of the receiver value, printed in the base represented by the argument. Argument value must be less than 36. rem: Remainder after receiver is divided by argu- ment value. timesRepeat: Repeat argument block the number of times given by the receiver. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result 5 + 4 7 5 allMask: 4 True 4 allMask: 5 False 5 anyMask: 4 True 5 bitAnd: 3 1 5 bitOr: 3 7 5 bitInvert -6 254 radix: 16 16rFE class I✓I✓I✓In✓n✓n✓nt✓t✓t✓te✓e✓e✓eg✓g✓g✓ge✓e✓e✓er✓r✓r✓r (continued) -5 // 4 -2 -5 quo: 4 -1 -5 \\ 4 1 -5 rem: 4 -1 8 factorial 40320 Object Magnitude Number F✓F✓F✓Fl✓l✓l✓lo✓o✓o✓oa✓a✓a✓at✓t✓t✓t The class F✓F✓F✓Fl✓l✓l✓lo✓o✓o✓oa✓a✓a✓at✓t✓t✓t provides protocol for objects with floating point values. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓T_✓o _✓r == Object equality test. Return true if the receiver and argument represent the same floating point value. _✓n |✓^ Floating exponentiation. arcCos Return a R✓R✓R✓Ra✓a✓a✓ad✓d✓d✓di✓i✓i✓ia✓a✓a✓an✓n✓n✓n representing the arcCos of the receiver. arcSin Return a R✓R✓R✓Ra✓a✓a✓ad✓d✓d✓di✓i✓i✓ia✓a✓a✓an✓n✓n✓n representing the arcSin of the receiver. arcTan Return a R✓R✓R✓Ra✓a✓a✓ad✓d✓d✓di✓i✓i✓ia✓a✓a✓an✓n✓n✓n representing the arcTan of the receiver. asFloat Return the receiver. ceiling Return the Integer ceiling of the receiver. coerce: Coerce the argument into being type Float. exp Return e raised to the receiver value. floor Return the Integer floor of the receiver. fractionPart Return the fractional part of the receiver. _✓n gamma Return the value of the gamma function applied to the receiver value. integerPart Return the integer part of the receiver. ln Return the natural log of the receiver. radix: Return a string containing the printable representation of the receiver in the given radix. Argument must be an Integer less than 36. rounded Return the receiver rounded to the nearest integer. class F✓F✓F✓Fl✓l✓l✓lo✓o✓o✓oa✓a✓a✓at✓t✓t✓t (continued) sqrt Return the square root of the receiver. truncated Return the receiver truncated to the nearest integer. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result 4.2 * 3 12.6 2.1 |✓^ 4 19.4481 2.1 raisedTo: 4 19.4481 0.5 arcSin 0.523599 radians 2.1 reciprocal 0.47619 4.3 sqrt 2.07364 Object Magnitude R✓R✓R✓Ra✓a✓a✓ad✓d✓d✓di✓i✓i✓ia✓a✓a✓an✓n✓n✓n The class R✓R✓R✓Ra✓a✓a✓ad✓d✓d✓di✓i✓i✓ia✓a✓a✓an✓n✓n✓n is used to represent radians. Radians are a unit of measurement, independent of other numbers. Only radians will responds to the trigonometric functions such as _✓s_✓i_✓n and _✓c_✓o_✓s. Numbers can be converted into radians by passing them the message _✓r_✓a_✓d_✓i_✓a_✓n_✓s. Similarly, radians can be converted into numbers by sending them the message _✓a_✓s_✓F_✓l_✓o_✓a_✓t. Notice that only a limited range of arithmetic operations are permitted on Radians. Radians are normalized to be between 0 and 2J. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓t_✓o + Argument must be a Radian. Add the two radi- ans together and return the normalized result. - Argument must be a Radian. Subtract the argument from the receiver and return the normalized result. * Argument must be a Number. Multiply the receiver by the argument amount and return the normalized result. / Argument must be a Number. Divide the receiver by the argument amount and return the normalized result. asFloat Return the receiver as a floating point number. cos Return a floating point number representing the cosine of the receiver. sin Return a floating point number representing the sine of the receiver. tan Return a floating point number representing the tangent of the receiver. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result 0.5236 radians sin 0.5 0.5236 radians cos 0.866025 0.5236 radians tan 0.577352 0.5 arcSin asFloat 0.523599 Object Magnitude P✓P✓P✓Po✓o✓o✓oi✓i✓i✓in✓n✓n✓nt✓t✓t✓t P✓P✓P✓Po✓o✓o✓oi✓i✓i✓in✓n✓n✓nt✓t✓t✓ts are used to represent pairs of quantities, such as coordinate pairs. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓T_✓o < True if both values of the receiver are less than the corresponding values in the argu- ment. <= True if the first value is less than or equal to the corresponding value in the argument, and the second value is less than the corresponding value in the argument. >= True if both values of the receiver are greater than or equal to the corresponding values in the argument. * Return a new point with coordinates multi- plied by the argument value. / Return a new point with coordinates divided by the argument value. // Return a new point with coordinates divided by the argument value. + Return a new point with coordinates offset by the corresponding values in the argument. abs Return a new point with coordinates having the absolute value of the receiver. dist: Return the Euclidean distance between the receiver and the argument point. max: The argument must be a P✓P✓P✓Po✓o✓o✓oi✓i✓i✓in✓n✓n✓nt✓t✓t✓t. Return the lower right corner of the rectangle defined by the receiver and the argument. min: The argument must be a P✓P✓P✓Po✓o✓o✓oi✓i✓i✓in✓n✓n✓nt✓t✓t✓t. Return the upper left corner of the rectangle defined by the receiver and the argument. transpose Return a new point with coordinates being the transpose of the receiver. class P✓P✓P✓Po✓o✓o✓oi✓i✓i✓in✓n✓n✓nt✓t✓t✓t (continued) x Return the first coordinate of the receiver. x: Set the first coordinate of the receiver. x:y: Sets both coordinates of the receiver. y Return the second coordinate of the receiver. y: Set the second coordinate of the receiver. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result (10@12) < (11@14) True (10@12) < (11@11) False (10@12) max: (11@11) 11@12 (10@12) min: (11@11) 10@11 (10@12) dist: (11@14) 2.23607 (10@12) transpose 12@10 Object R✓R✓R✓Ra✓a✓a✓an✓n✓n✓nd✓d✓d✓do✓o✓o✓om✓m✓m✓m The class R✓R✓R✓Ra✓a✓a✓an✓n✓n✓nd✓d✓d✓do✓o✓o✓om✓m✓m✓m provides protocol for random number generation. Sending the message _✓n_✓e_✓x_✓t to an instance of R✓R✓R✓Ra✓a✓a✓an✓n✓n✓n-✓-✓-✓- d✓d✓d✓do✓o✓o✓om✓m✓m✓m results in a F✓F✓F✓Fl✓l✓l✓lo✓o✓o✓oa✓a✓a✓at✓t✓t✓t between 0.0 and 1.0, randomly distri- buted. By default, the pseudo random sequence is the same for each object in class R✓R✓R✓Ra✓a✓a✓an✓n✓n✓nd✓d✓d✓do✓o✓o✓om✓m✓m✓m. This can be altered using the message _✓r_✓a_✓n_✓d_✓o_✓m_✓i_✓z_✓e. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓T_✓o _✓n between:and: Return a random number uniformly distributed between the two arguments. _✓n first Return a random number between 0.0 and 1.0. This message merely provides consistency with protocol for other sequences, such as Arrays or Intervals. next Return a random number between 0.0 and 1.0. _✓d next: Return an A✓A✓A✓Ar✓r✓r✓rr✓r✓r✓ra✓a✓a✓ay✓y✓y✓y containing the next n random numbers, where n is the argument value. _✓n randInteger: The argument must be an integer. Return a random integer between 1 and the value given. _✓n randomize Change the pseudo-random number generator seed by a time dependent value. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result i <- Random new i next 0.759 i next 0.157 i next: 3 #( 0.408 0.278 0.547 ) i randInteger: 12 5 i between: 4 and: 17.5 10.0 Object C✓C✓C✓Co✓o✓o✓ol✓l✓l✓ll✓l✓l✓le✓e✓e✓ec✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓n The class C✓C✓C✓Co✓o✓o✓ol✓l✓l✓ll✓l✓l✓le✓e✓e✓ec✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓n provides protocol for groups of objects, such as A✓A✓A✓Ar✓r✓r✓rr✓r✓r✓ra✓a✓a✓ay✓y✓y✓ys or S✓S✓S✓Se✓e✓e✓et✓t✓t✓ts. The different forms of col- lections are distinguished by several characteristics, among them whether the size of the collection is fixed or unbounded, the presence or absence of an ordering, and their insertion or access method. For example, an A✓A✓A✓Ar✓r✓r✓rr✓r✓r✓ra✓a✓a✓ay✓y✓y✓y is a col- lection with a fixed size and ordering, indexed by integer keys. A D✓D✓D✓Di✓i✓i✓ic✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓na✓a✓a✓ar✓r✓r✓ry✓y✓y✓y, on the other hand, has no fixed size or ordering, and can be indexed by arbitrary elements. Nevertheless, A✓A✓A✓Ar✓r✓r✓rr✓r✓r✓ra✓a✓a✓ay✓y✓y✓ys✓s✓s✓s and D✓D✓D✓Di✓i✓i✓ic✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓na✓a✓a✓ar✓r✓r✓ry✓y✓y✓ys✓s✓s✓s share many features in common, such as their access method (_✓a_✓t: and _✓a_✓t:_✓p_✓u_✓t:), and the ability to respond to _✓c_✓o_✓l_✓l_✓e_✓c_✓t:, _✓s_✓e_✓l_✓e_✓c_✓t:, and many other messages. The table below lists some of the characteristics of several forms of collections: ___________________________________________________________________ Name Creation Size Ordered? Insertion Access Method fixed? method method ___________________________________________________________________ Bag/Set new no no add: includes: Dictionary new no no at:put: at: Interval n to: m yes yes none at: List new no yes addFirst: first addLast: last Array new: yes yes at:put: at: String new: yes yes at:put: at: ___________________________________________________________________ |✓|✓|✓|✓|✓|✓|✓|✓|✓|✓|✓|✓|✓|✓|✓|✓|✓|✓| |✓|✓|✓|✓|✓|✓|✓|✓|✓|✓|✓|✓|✓|✓|✓|✓|✓|✓| The list below shows messages that are shared in common by all collections. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓t_✓o addAll: The argument must be a C✓C✓C✓Co✓o✓o✓ol✓l✓l✓ll✓l✓l✓le✓e✓e✓ec✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓n. Add all the elements of the argument collection to the receiver collection. asArray Return a new collection of type A✓A✓A✓Ar✓r✓r✓rr✓r✓r✓ra✓a✓a✓ay✓y✓y✓y con- taining the elements from the receiver col- lection. If the receiver was ordered, the elements will be in the same order in the new class C✓C✓C✓Co✓o✓o✓ol✓l✓l✓ll✓l✓l✓le✓e✓e✓ec✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓n (continued) collection, otherwise the elements will be in an arbitrary order. asBag Return a new collection of type B✓B✓B✓Ba✓a✓a✓ag✓g✓g✓g contain- ing the elements from the receiver collec- tion. _✓n asList Return a new collection of type L✓L✓L✓Li✓i✓i✓is✓s✓s✓st✓t✓t✓t contain- ing the elements from the receiver collec- tion. If the receiver was ordered, the ele- ments will be in the same order in the new collection, otherwise the elements will be in an arbitrary order. asSet Return a new collection of type S✓S✓S✓Se✓e✓e✓et✓t✓t✓t contain- ing the elements from the receiver collec- tion. asString Return a new collection of type S✓S✓S✓St✓t✓t✓tr✓r✓r✓ri✓i✓i✓in✓n✓n✓ng✓g✓g✓g con- taining the elements from the receiver col- lection. The elements to be included must all be of type C✓C✓C✓Ch✓h✓h✓ha✓a✓a✓ar✓r✓r✓ra✓a✓a✓ac✓c✓c✓ct✓t✓t✓te✓e✓e✓er✓r✓r✓r. If the receiver was ordered, the elements will be in the same order in the new collection, otherwise the elements will be listed in an arbitrary order. coerce: The argument must be a collection. Return a collection, of the same type as the receiver, containing elements from the argument collec- tion. This message is redefined in most subclasses of collection. collect: The argument must be a one argument block. Return a new collection, like the receiver, containing the result of evaluating the argu- ment block on each element of the receiver collection. detect: The argument must be a one argument block. Return the first element in the receiver col- lection for which the argument block evalu- ates true. Report an error and return n✓n✓n✓ni✓i✓i✓il✓l✓l✓l if no such element exists. Note that in unor- dered collections (such as B✓B✓B✓Ba✓a✓a✓ag✓g✓g✓gs✓s✓s✓s or D✓D✓D✓Di✓i✓i✓ic✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓n-✓-✓-✓- a✓a✓a✓ar✓r✓r✓ry✓y✓y✓ys✓s✓s✓s) the first element to be encountered that will satisfy the condition may not be easily predictable. detect:ifAbsent: Return the first element in the receiver col- lection for which the first argument block evaluates true. Return the result of evaluating the second argument if no such class C✓C✓C✓Co✓o✓o✓ol✓l✓l✓ll✓l✓l✓le✓e✓e✓ec✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓n (continued) element exists. do: The argument must be a one argument block. Evaluate the argument block on each element in the receiver collection. includes: Return true if the receiver collection con- tains the argument. inject:into: The first argument must be a value, the second a two argument block. The second argument is evaluated once for each element in the receiver collection, passing as argu- ments the result of the previous evaluation (starting with the first argument) and the element. The value returned is the final value generated. isEmpty Return true if the receiver collection con- tains no elements. occurrencesOf:Return the number of times the argument occurs in the receiver collection. remove: Remove the argument from the receiver collec- tion. Report an error if the element is not contained in the receiver collection. remove:ifAbsent: Remove the first argument from the receiver collection. Evaluate the second argument if not present. reject: The argument must be a one argument block. Return a new collection like the receiver containing all elements for which the argu- ment block returns false. select: The argument must be a one argument block. Return a new collection like the receiver containing all elements for which the argu- ment block returns true. size Return the number of elements in the receiver collection. class C✓C✓C✓Co✓o✓o✓ol✓l✓l✓ll✓l✓l✓le✓e✓e✓ec✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓n (continued) _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result i <- 'abacadabra' i size 10 i asArray #( $a $b $a $c $a $d $a $b $r $a ) i asBag Bag ( $a $a $a $a $a $r $b $b $c $d) i asSet Set ( $a $r $b $c $d ) i occurrencesOf: $a 5 i reject: [:x | x isVowel] bcdbr Object Collection B✓B✓B✓Ba✓a✓a✓ag✓g✓g✓g/✓/✓/✓/S✓S✓S✓Se✓e✓e✓et✓t✓t✓t B✓B✓B✓Ba✓a✓a✓ag✓g✓g✓gs✓s✓s✓s and S✓S✓S✓Se✓e✓e✓et✓t✓t✓ts✓s✓s✓s are each unordered collections of ele- ments. Elements in the collections do not have keys, but are added and removed directly. The difference between a B✓B✓B✓Ba✓a✓a✓ag✓g✓g✓g and a S✓S✓S✓Se✓e✓e✓et✓t✓t✓t is that each element can occur any number of times in a B✓B✓B✓Ba✓a✓a✓ag✓g✓g✓g, whereas only one copy is inserted into a S✓S✓S✓Se✓e✓e✓et✓t✓t✓t. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓t_✓o add: Add the indicated element to the receiver collection. add:withOccurences: (B✓B✓B✓Ba✓a✓a✓ag✓g✓g✓g only) Add the indicated element to the receiver B✓B✓B✓Ba✓a✓a✓ag✓g✓g✓g the given number of times. _✓n first Return the first element from the receiver collection. As the collection is unordered, the first element depends upon certain values in the internal representation, and is not guaranteed to be any specific element in the collection. _✓n next Return the next element in the collection. In conjunction with _✓f_✓i_✓r_✓s_✓t, this can be used to access each element of the collection in turn. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result i <- (1 to: 6) asBag Bag ( 1 2 3 4 5 6 ) i size 6 i select: [:x | (x \\ 2) strictlyPositive]Bag ( 1 3 5 ) i collect: [:x | x \\ 3] Bag ( 0 0 1 1 2 2 ) j <- ( i collect: [:x | x \\ 3] ) asSet Set ( 0 1 2 ) j size 3 N✓N✓N✓No✓o✓o✓ot✓t✓t✓te✓e✓e✓e:✓:✓:✓: Since B✓B✓B✓Ba✓a✓a✓ag✓g✓g✓gs✓s✓s✓s and S✓S✓S✓Se✓e✓e✓et✓t✓t✓ts✓s✓s✓s are unordered, there is no way to establish a mapping between the elements of the Bag i in the example above and the corresponding elements in the collec- tion that resulted from the message collect: [:x | x \\ 3]. Object Collection K✓K✓K✓Ke✓e✓e✓ey✓y✓y✓ye✓e✓e✓ed✓d✓d✓dC✓C✓C✓Co✓o✓o✓ol✓l✓l✓ll✓l✓l✓le✓e✓e✓ec✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓n The class K✓K✓K✓Ke✓e✓e✓ey✓y✓y✓ye✓e✓e✓ed✓d✓d✓dC✓C✓C✓Co✓o✓o✓ol✓l✓l✓ll✓l✓l✓le✓e✓e✓ec✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓n provides protocol for collec- tions with keys, such as D✓D✓D✓Di✓i✓i✓ic✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓na✓a✓a✓ar✓r✓r✓ry✓y✓y✓ys✓s✓s✓s and A✓A✓A✓Ar✓r✓r✓rr✓r✓r✓ra✓a✓a✓ay✓y✓y✓ys✓s✓s✓s. Since each entry in the collection has both a key and value, the method _✓a_✓d_✓d: is no longer appropriate. Instead, the method _✓a_✓t:_✓p_✓u_✓t:, which provides both a key and a value, must be used. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓t_✓o asDictionary Return a new collection of type D✓D✓D✓Di✓i✓i✓ic✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓na✓a✓a✓ar✓r✓r✓ry✓y✓y✓y containing the elements from the receiver collection. at: Return the item in the receiver collection whose key matches the argument. Produces and error message, and returns nil, if no item is currently in the receiver collection under the given key. at:ifAbsent: Return the element stored in the dictionary under the key given by the first argument. Return the result of evaluating the second argument if no such element exists. atAll:put: The first argument must be a collection con- taining keys valid for the receiver. At each location given by a key in the first argument place the second argument. binaryDo: The argument must be a two argument block. This message is similar to _✓d_✓o:, however both the key and the element value are passed as argument to the block. includesKey: Return true if the indicated key is valid for the receiver collection. indexOf: Return the key value of the first element in the receiver collection matching the argu- ment. Produces an error message if no such element exists. Note that, as with the mes- sage _✓d_✓e_✓t_✓e_✓c_✓t:, in unordered collections the first element may not be related in any way to the order in which elements were placed into the collection, but is rather implemen- tation dependent. indexOf:ifAbsent: Return the key value of the first element in the receiver collection matching the argu- ment. Return the result of evaluating the class K✓K✓K✓Ke✓e✓e✓ey✓y✓y✓ye✓e✓e✓ed✓d✓d✓dC✓C✓C✓Co✓o✓o✓ol✓l✓l✓ll✓l✓l✓le✓e✓e✓ec✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓n (continued) second argument if no such element exists. keys Return a Set containing the keys for the receiver collection. keysDo: The argument must be a one argument block. Similar to _✓d_✓o:, except that the values passed to the block are the keys of the receiver collection. keysSelect: Similar to _✓s_✓e_✓l_✓e_✓c_✓t, except that the selection is made on the basis of keys instead of values. removeKey: Remove the object with the given key from the receiver collection. Print an error message, and return n✓n✓n✓ni✓i✓i✓il✓l✓l✓l, if no such object exists. Return the value of the deleted item. removeKey:ifAbsent: Remove the object with the given key from the receiver collection. Return the result of evaluating the second argument if no such object exists. values Return a Bag containing the values from the receiver collection. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result i <- 'abacadabra' i atAll: (1 to: 7 by: 2) put: $e ebecedebra i indexOf: $r 9 i atAll: i keys put: $z zzzzzzzzzz i keys Set ( 1 2 3 4 5 6 7 8 9 10 ) i values Bag ( $z $z $z $z $z $z $z $z $z $z ) #(how odd) asDictionary Dictionary ( 1 @ #how 2 @ odd ) Object Collection KeyedCollection D✓D✓D✓Di✓i✓i✓ic✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓na✓a✓a✓ar✓r✓r✓ry✓y✓y✓y A D✓D✓D✓Di✓i✓i✓ic✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓na✓a✓a✓ar✓r✓r✓ry✓y✓y✓y is an unordered collection of elements, as are B✓B✓B✓Ba✓a✓a✓ag✓g✓g✓gs✓s✓s✓s and S✓S✓S✓Se✓e✓e✓et✓t✓t✓ts✓s✓s✓s. However, unlike these collections, ele- ments inserted and removed from a D✓D✓D✓Di✓i✓i✓ic✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓na✓a✓a✓ar✓r✓r✓ry✓y✓y✓y must reference an explicit key. Both the key and value portions of an ele- ment can be any object, although commonly the keys are instances of S✓S✓S✓Sy✓y✓y✓ym✓m✓m✓mb✓b✓b✓bo✓o✓o✓ol✓l✓l✓l or N✓N✓N✓Nu✓u✓u✓um✓m✓m✓mb✓b✓b✓be✓e✓e✓er✓r✓r✓r. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓t_✓o at:put: Place the second argument into the receiver collection under the key given by the first argument. currentKey Return the key of the last element yielded in response to a _✓f_✓i_✓r_✓s_✓t or _✓n_✓e_✓x_✓t request. _✓n first Return the first element of the receiver col- lection. Return nil if the receiver collec- tion is empty. _✓n next Return the next element of the receiver col- lection, or nil if no such element exists. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result i <- Dictionary new i at: #abc put: #def i at: #pqr put: #tus i at: #xyz put: #wrt i print Dictionary ( #abc @ #def #pqr @ #tus #xyz @ #wrt ) i size 3 i at: #pqr #tus i indexOf: #tus #pqr i keys Set ( #abc #pqr #xyz ) i values Bag ( #wrt #def # tus ) i collect: [:x | x asString at: 2]Dictionary ( #abc @ $e #pqr @ $u #xyz @ $r) Object Collection KeyedCollection Dictionary S✓S✓S✓Sm✓m✓m✓ma✓a✓a✓al✓l✓l✓ll✓l✓l✓lt✓t✓t✓ta✓a✓a✓al✓l✓l✓lk✓k✓k✓k The class S✓S✓S✓Sm✓m✓m✓ma✓a✓a✓al✓l✓l✓ll✓l✓l✓lt✓t✓t✓ta✓a✓a✓al✓l✓l✓lk✓k✓k✓k provides protocol for the pseudo variable s✓s✓s✓sm✓m✓m✓ma✓a✓a✓al✓l✓l✓ll✓l✓l✓lt✓t✓t✓ta✓a✓a✓al✓l✓l✓lk✓k✓k✓k. Since it is a subclass of Dictionary, this variable can be used to store information, and thus provide a means of communication between objects. Other messages modify various parameters used by the Little Smalltalk system. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓T_✓o _✓n date Return the current date and time as a string. _✓n display Set execution display to display the result of every expression typed, but not for assignments. Note that the display behavior can also be modified using the -d argument on the command line. _✓n displayAssignSet execution display to display the result of every expression typed, including assign- ment statements. _✓n doPrimitive:withArguments: Execute the indicated primitive with argu- ments given by the second array. A few prim- itives (such as those dealing with process management) cannot be executed in this manner. _✓n noDisplay Turn off execution display - no results will be displayed unless explicitly requested by the user. _✓d perform:withArguments: Send indicated message to the receiver, using the arguments given. The first value in the argument array is taken to be the receiver of the message. Unpredictable results if the number of arguments is not appropriate for the given message. _✓n sh: The argument, which must be a string, is exe- cuted as a Unix command by the shell. The value returned is the termination status of the shell. _✓n time: The argument must be a block. The block is executed, and the number of seconds elapsed during execution returned. Time is only class S✓S✓S✓Sm✓m✓m✓ma✓a✓a✓al✓l✓l✓ll✓l✓l✓lt✓t✓t✓ta✓a✓a✓al✓l✓l✓lk✓k✓k✓k (continued) accurate to within about one second. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result smalltalk date Fri Apr 12 16:15:42 1985 smalltalk perform: #+ withArguments: #(2 5)7 smalltalk doPrimitive: 10 withArguments: #(2 5)7 Object Collection KeyedCollection S✓S✓S✓Se✓e✓e✓eq✓q✓q✓qu✓u✓u✓ue✓e✓e✓en✓n✓n✓nc✓c✓c✓ce✓e✓e✓ea✓a✓a✓ab✓b✓b✓bl✓l✓l✓le✓e✓e✓eC✓C✓C✓Co✓o✓o✓ol✓l✓l✓ll✓l✓l✓le✓e✓e✓ec✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓n The class S✓S✓S✓Se✓e✓e✓eq✓q✓q✓qu✓u✓u✓ue✓e✓e✓en✓n✓n✓nc✓c✓c✓ce✓e✓e✓ea✓a✓a✓ab✓b✓b✓bl✓l✓l✓le✓e✓e✓eC✓C✓C✓Co✓o✓o✓ol✓l✓l✓ll✓l✓l✓le✓e✓e✓ec✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓n contains protocol for collections that have a definite sequential ordering and are indexed by integer keys. Since there is a fixed order for elements, it is possible to refer to the last element in a S✓S✓S✓Se✓e✓e✓eq✓q✓q✓qu✓u✓u✓ue✓e✓e✓en✓n✓n✓nc✓c✓c✓ce✓e✓e✓ea✓a✓a✓ab✓b✓b✓bl✓l✓l✓le✓e✓e✓eC✓C✓C✓Co✓o✓o✓ol✓l✓l✓ll✓l✓l✓le✓e✓e✓ec✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓n. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓t_✓o , Appends the argument collection to the receiver collection, returning a new collec- tion of the same type as the receiver. copyFrom:to: Return a new collection, like the receiver, containing the designated subportion of the receiver collection. copyWith: Return a new collection, like the receiver, with the argument added to the end. copyWithout: Return a new collection, like the receiver, with all occurrences of the argument removed. equals:startingAt: The first argument must be a S✓S✓S✓Se✓e✓e✓eq✓q✓q✓qu✓u✓u✓ue✓e✓e✓en✓n✓n✓nc✓c✓c✓ce✓e✓e✓ea✓a✓a✓ab✓b✓b✓bl✓l✓l✓le✓e✓e✓eC✓C✓C✓Co✓o✓o✓ol✓l✓l✓l-✓-✓-✓- l✓l✓l✓le✓e✓e✓ec✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓n. Return true if each element of the receiver collection is equal to the corresponding element in the argument offset by the amount given in the second argument. findFirst: Find the key for the first element whose value satisfies the argument block. Produce an error message if no such element exists. findFirst:ifAbsent: Both arguments must be blocks. Find the key for the first element whose value satisfies the first argument block. If no such element exists return the value of the second argu- ment. findLast: Find the key for the last element whose value satisfies the argument block. Produce an error message if no such element exists. findLast:ifAbsent: Both arguments must be blocks. Find the key for the last element whose value satisfies the first argument block. If no such element exists return the value of the second class S✓S✓S✓Se✓e✓e✓eq✓q✓q✓qu✓u✓u✓ue✓e✓e✓en✓n✓n✓nc✓c✓c✓ce✓e✓e✓ea✓a✓a✓ab✓b✓b✓bl✓l✓l✓le✓e✓e✓eC✓C✓C✓Co✓o✓o✓ol✓l✓l✓ll✓l✓l✓le✓e✓e✓ec✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓n (continued) argument block. firstKey Return the first key valid for the receiver collection. indexOfSubCollection:startingAt: Starting at the position given by the second argument, find the next block of elements in the receiver collection which match the col- lection given by the first argument, and return the index for the start of that block. Produce an error message if no such position exists. indexOfSubCollection:startingAt:ifAbsent: Similar to _✓i_✓n_✓d_✓e_✓x_✓O_✓f_✓S_✓u_✓b_✓C_✓o_✓l_✓l_✓e_✓c_✓t_✓i_✓o_✓n:_✓s_✓t_✓a_✓r_✓t_✓i_✓n_✓g_✓A_✓t:, except that the result of the exception block is produced if no position exists matching the pattern. last Return the last element in the receiver col- lection. lastKey Return the last key valid for the receiver collection. replaceFrom:to:with: Replace the elements in the receiver collec- tion in the positions indicated by the first two arguments with values taken from the col- lection given by the third argument. replaceFrom:to:with:startingAt: Replace the elements in the receiver collec- tion in the positions indicated by the first two arguments with values taken from the col- lection given in the third argument, starting at the position given by the fourth argument. _✓n reversed Return a collection, like the receiver, with elements reversed. reverseDo: Similar to _✓d_✓o:, except that the items are presented in reverse order. _✓n sort Return a collection, like the receiver, with the elements sorted using the comparison <=. Elements must be able to respond to the binary message <=. _✓n sort: The argument must be a two argument block which yields a boolean. Return a collection, like the receiver, sorted using the argument to compare elements for the purpose of class S✓S✓S✓Se✓e✓e✓eq✓q✓q✓qu✓u✓u✓ue✓e✓e✓en✓n✓n✓nc✓c✓c✓ce✓e✓e✓ea✓a✓a✓ab✓b✓b✓bl✓l✓l✓le✓e✓e✓eC✓C✓C✓Co✓o✓o✓ol✓l✓l✓ll✓l✓l✓le✓e✓e✓ec✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓n (continued) ordering. with:do: The second argument must be a two argument block. Present one element from the receiver collection and from the collection given by the first argument in turn to the second argument block. An error message is given if the collections do not have the same number of elements. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result i <- 'abacadabra' i copyFrom: 4 to: 8 cadab i copyWith: $z abacadabraz i copyWithout: $a bcdbr i findFirst: [:x | x > $m] 9 i indexOfSubCollection: 'dab' startingAt: 16 i reversed arbadacaba i , i reversed abacadabraarbadacaba i sort: [:x :y | x >= y] rdcbbaaaaa Object Collection KeyedCollection SequenceableCollection I✓I✓I✓In✓n✓n✓nt✓t✓t✓te✓e✓e✓er✓r✓r✓rv✓v✓v✓va✓a✓a✓al✓l✓l✓l The class I✓I✓I✓In✓n✓n✓nt✓t✓t✓te✓e✓e✓er✓r✓r✓rv✓v✓v✓va✓a✓a✓al✓l✓l✓l represents a sequence of numbers in an arithmetic sequence, either ascending or descending. Instances of I✓I✓I✓In✓n✓n✓nt✓t✓t✓te✓e✓e✓er✓r✓r✓rv✓v✓v✓va✓a✓a✓al✓l✓l✓l are created by numbers in response to the message _✓t_✓o: or _✓t_✓o:_✓b_✓y:. In conjunction with the message _✓d_✓o:, I✓I✓I✓In✓n✓n✓nt✓t✓t✓te✓e✓e✓er✓r✓r✓rv✓v✓v✓va✓a✓a✓al✓l✓l✓ls✓s✓s✓s create a control structure similar to do or for loops in Algol like languages. For example: (1 to: 10) do: [:x | x print] will print the numbers 1 through 10. Although they are a collection, I✓I✓I✓In✓n✓n✓nt✓t✓t✓te✓e✓e✓er✓r✓r✓rv✓v✓v✓va✓a✓a✓al✓l✓l✓ls✓s✓s✓s cannot be added to. They can, how- ever, be accessed randomly using the message _✓a_✓t:. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓t_✓o first Produce the first element from the interval. In conjunction with _✓l_✓a_✓s_✓t, this message may be used to produce each element from the inter- val in turn. Note that I✓I✓I✓In✓n✓n✓nt✓t✓t✓te✓e✓e✓er✓r✓r✓rv✓v✓v✓va✓a✓a✓al✓l✓l✓ls✓s✓s✓s also respond to the message _✓a_✓t:, which can be used to produce elements in an arbitrary order. from:to:by: Initialize the upper and lower bounds and the step size for the receiver. (This is used principally internally by the method for number to create new Intervals). next Produce the next element from the interval. size Return the number of elements that will be generated in producing the interval. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result (7 to: 13 by: 3) asArray #( 7 10 13 ) (7 to: 13 by: 3) at: 2 10 (1 to: 10) inject: 0 into: [:x :y | x + y]55 (7 to: 13) copyFrom: 2 to: 5 #( 8 9 10 11 ) (3 to: 5) copyWith: 13 #( 3 4 5 13 ) (3 to: 5) copyWithout: 4 #( 3 5 ) (2 to: 4) equals: (1 to: 4) startingAt: 2True Object Collection KeyedCollection SequenceableCollection L✓L✓L✓Li✓i✓i✓is✓s✓s✓st✓t✓t✓t Lists represent collections with a fixed order, but indefinite size. No keys are used, and elements are added or removed from one end of the other. Used in this way, Lists can perform as _✓s_✓t_✓a_✓c_✓k_✓s or as _✓q_✓u_✓e_✓u_✓e_✓s. The table below illustrates how stack and queue operations can be imple- mented in terms of messages to instances of List. _✓s_✓t_✓a_✓c_✓k _✓o_✓p_✓e_✓r_✓a_✓t_✓i_✓o_✓n_✓s _✓q_✓u_✓e_✓u_✓e _✓o_✓p_✓e_✓r_✓a_✓t_✓i_✓o_✓n_✓s _____________________________________________________________ push addLast: add addLast: pop removeLast first in queue first top last remove first in queue removeFirst test empty isEmpty test empty isEmpty |✓|✓|✓|✓|✓|✓| _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓t_✓o add: Add the element to the beginning of the receiver collection. This is the same as _✓a_✓d_✓d_✓F_✓i_✓r_✓s_✓t:. addAllFirst: The argument must be a SequenceableCollec- tion. The elements of the argument are added, in order, to the front of the receiver collection. addAllLast: The argument must be a SequenceableCollec- tion. The elements of the argument are added, in order, to the end of the receiver collection. addFirst: The argument is added to the front of the receiver collection. addLast: The argument is added to the back of the receiver collection. removeFirst Remove the first element from the receiver collection, returning the removed value. removeLast Remove the last element from the receiver collection, returning the removed value. class L✓L✓L✓Li✓i✓i✓is✓s✓s✓st✓t✓t✓t (continued) _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result i <- List new i addFirst: 2 / 3 List ( 0.6666 ) i add: $A i addAllLast: (12 to: 14 by: 2) i print List ( 0.6666 $A 12 14 ) i first 0.6666 i removeLast 14 i print List ( 0.6666 $A 12 ) Object Collection KeyedCollection SequenceableCollection List S✓S✓S✓Se✓e✓e✓em✓m✓m✓ma✓a✓a✓ap✓p✓p✓ph✓h✓h✓ho✓o✓o✓or✓r✓r✓re✓e✓e✓e Semaphores are used to synchronize concurrently running P✓P✓P✓Pr✓r✓r✓ro✓o✓o✓oc✓c✓c✓ce✓e✓e✓es✓s✓s✓ss✓s✓s✓se✓e✓e✓es✓s✓s✓s. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓T_✓o new: If created using _✓n_✓e_✓w, a S✓S✓S✓Se✓e✓e✓em✓m✓m✓ma✓a✓a✓ap✓p✓p✓ph✓h✓h✓ho✓o✓o✓or✓r✓r✓re✓e✓e✓e starts out with zero excess signals. Alternatively, a S✓S✓S✓Se✓e✓e✓em✓m✓m✓ma✓a✓a✓ap✓p✓p✓ph✓h✓h✓ho✓o✓o✓or✓r✓r✓re✓e✓e✓e can be created with an arbitrary number of excess signals by giving it an argument to _✓n_✓e_✓w:. signal If there is a process blocked on the sema- phore is it scheduled for execution, other- wise the number of excess signals is incre- mented by one. wait If there are excess signals associated with the semaphore the number of signals is decre- mented by one, otherwise the current process is placed on the semaphore queue. Object Collection KeyedCollection SequenceableCollection F✓F✓F✓Fi✓i✓i✓il✓l✓l✓le✓e✓e✓e A F✓F✓F✓Fi✓i✓i✓il✓l✓l✓le✓e✓e✓e is a type of collection where the elements of the collection are stored on an external medium, typically a disk. For this reason, although most operations on collec- tions are defined for files, many can be quite slow in exe- cution. A file can be opened on one of three _✓m_✓o_✓d_✓e_✓s: In _✓c_✓h_✓a_✓r_✓a_✓c_✓t_✓e_✓r mode every read returns a single character from the file. In _✓i_✓n_✓t_✓e_✓g_✓e_✓r mode every read returns a single word, as an integer value. In _✓s_✓t_✓r_✓i_✓n_✓g mode every read returns a single line, as a S✓S✓S✓St✓t✓t✓tr✓r✓r✓ri✓i✓i✓in✓n✓n✓ng✓g✓g✓g. For writing, character and string modes will write the string representation of the argument, while integer mode must write only a single integer. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓T_✓o at: Return the object stored at the indicated position. Position is given as a character count from the start of the file. at:put: Place the object at the indicated position in the file. Position is given as a character count from the start of the file. characterModeSet the mode of the receiver file to _✓c_✓h_✓a_✓r_✓a_✓c_✓- _✓t_✓e_✓r. currentKey Return the current position in the file, as a character count from the start of the file. integerMode Set the mode of the receiver file to _✓i_✓n_✓t_✓e_✓g_✓e_✓r. open: Open the indicated file for reading. The argument must be a S✓S✓S✓St✓t✓t✓tr✓r✓r✓ri✓i✓i✓in✓n✓n✓ng✓g✓g✓g. open:for: The _✓f_✓o_✓r: argument must be one of 'r', 'w' or 'r+' (see fopen(3) in the Unix programmers manual). Open the file in the indicated mode. read Return the next object from the file. size Return the size of the file, in character counts. stringMode Set the mode of the receiver file to _✓s_✓t_✓r_✓i_✓n_✓g. write: Write the argument into the file. Object Collection KeyedCollection SequenceableCollection A✓A✓A✓Ar✓r✓r✓rr✓r✓r✓ra✓a✓a✓ay✓y✓y✓ye✓e✓e✓ed✓d✓d✓dC✓C✓C✓Co✓o✓o✓ol✓l✓l✓ll✓l✓l✓le✓e✓e✓ec✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓n The class A✓A✓A✓Ar✓r✓r✓rr✓r✓r✓ra✓a✓a✓ay✓y✓y✓ye✓e✓e✓ed✓d✓d✓dC✓C✓C✓Co✓o✓o✓ol✓l✓l✓ll✓l✓l✓le✓e✓e✓ec✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓n provides protocol for col- lections with a Fixed size and integer keys. Unlike other collections, which are created using the message _✓n_✓e_✓w, instances of A✓A✓A✓Ar✓r✓r✓rr✓r✓r✓ra✓a✓a✓ay✓y✓y✓ye✓e✓e✓ed✓d✓d✓dC✓C✓C✓Co✓o✓o✓ol✓l✓l✓ll✓l✓l✓le✓e✓e✓ec✓c✓c✓ct✓t✓t✓ti✓i✓i✓io✓o✓o✓on✓n✓n✓n must be created using the one argument message _✓n_✓e_✓w:. The argument given with this message must be a positive integer, representing the size of the collection to be created. In addition to the protocol shown, many of the methods inherited from superclasses are redefined in this class. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓t_✓o = The argument must also be an A✓A✓A✓Ar✓r✓r✓rr✓r✓r✓ra✓a✓a✓ay✓y✓y✓y. Test whether the receiver and the argument have equal elements listed in the same order. at:ifAbsent: Return the element stored with the given key. Return the result of evaluating the second argument if the key is not valid for the receiver collection. _✓n padTo: Return an array like the received that is at least as long as the argument value. Returns the receiver if it is already longer than the argument. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result 'small' = 'small' True 'small' = 'SMALL' False 'small' asArray #( $s $m $a $l $l) 'small' asArray = 'small' True #(1 2 3) padTo: 5 #(1 2 3 nil nil) #(1 2 3) padTo: 2 #(1 2 3) Object Collection KeyedCollection SequenceableCollection ArrayedCollection A✓A✓A✓Ar✓r✓r✓rr✓r✓r✓ra✓a✓a✓ay✓y✓y✓y Instances of the class A✓A✓A✓Ar✓r✓r✓rr✓r✓r✓ra✓a✓a✓ay✓y✓y✓y are perhaps the most com- monly used data structure in Smalltalk programs. A✓A✓A✓Ar✓r✓r✓rr✓r✓r✓ra✓a✓a✓ay✓y✓y✓ys✓s✓s✓s are represented textually by a pound sign preceding the list of array elements. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓t_✓o at: Return the item stored in the position given by the argument. An error message is pro- duced, and n✓n✓n✓ni✓i✓i✓il✓l✓l✓l returned, if the argument is not a valid key. at:put: Store the second argument in the position given by the first argument. An error mes- sage is produced, and n✓n✓n✓ni✓i✓i✓il✓l✓l✓l returned, if the argument is not a valid key. grow: Return a new array one element larger than the receiver, with the argument value attached to the end. This is a slightly more efficient command than _✓c_✓o_✓p_✓y_✓W_✓i_✓t_✓h:, although the effect is the same. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result i <- #(110 101 97) i size 3 i <- i grow: 116 #( 110 101 97 116) i <- i collect: [:x | x asCharacter] #( #n #e #a #t ) i asString neat Object Collection KeyedCollection SequenceableCollection ArrayedCollection B✓B✓B✓By✓y✓y✓yt✓t✓t✓te✓e✓e✓eA✓A✓A✓Ar✓r✓r✓rr✓r✓r✓ra✓a✓a✓ay✓y✓y✓y A B✓B✓B✓By✓y✓y✓yt✓t✓t✓te✓e✓e✓eA✓A✓A✓Ar✓r✓r✓rr✓r✓r✓ra✓a✓a✓ay✓y✓y✓y is a special form of array in which the elements must be numbers in the range 0-255. Instances of B✓B✓B✓By✓y✓y✓yt✓t✓t✓te✓e✓e✓eA✓A✓A✓Ar✓r✓r✓rr✓r✓r✓ra✓a✓a✓ay✓y✓y✓y are given a very compact encoding, and are used extensively internally in the Little Smalltalk system. A B✓B✓B✓By✓y✓y✓yt✓t✓t✓te✓e✓e✓eA✓A✓A✓Ar✓r✓r✓rr✓r✓r✓ra✓a✓a✓ay✓y✓y✓y can be represented textually by a pound sign preceding the list of array elements surrounded by a pair of square braces. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓t_✓o at: Return the item stored in the position given by the argument. An error message is pro- duced, and n✓n✓n✓ni✓i✓i✓il✓l✓l✓l returned, if the argument is not a valid key. at:put: Store the second argument in the position given by the first argument. An error mes- sage is produced, and n✓n✓n✓ni✓i✓i✓il✓l✓l✓l returned, if the argument is not a valid key. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result i <- #[110 101 97] i size 3 i <- i copyWith: 116 #[ 110 101 97 116 ] i <- i asArray collect: [:x | x asCharacter]#( #n #e #a #t ) i asString neat Object Collection KeyedCollection SequenceableCollection ArrayedCollection S✓S✓S✓St✓t✓t✓tr✓r✓r✓ri✓i✓i✓in✓n✓n✓ng✓g✓g✓g Instances of the class S✓S✓S✓St✓t✓t✓tr✓r✓r✓ri✓i✓i✓in✓n✓n✓ng✓g✓g✓g are similar to A✓A✓A✓Ar✓r✓r✓rr✓r✓r✓ra✓a✓a✓ay✓y✓y✓ys✓s✓s✓s, except that the individual elements must be C✓C✓C✓Ch✓h✓h✓ha✓a✓a✓ar✓r✓r✓ra✓a✓a✓ac✓c✓c✓ct✓t✓t✓te✓e✓e✓er✓r✓r✓r. S✓S✓S✓St✓t✓t✓tr✓r✓r✓ri✓i✓i✓in✓n✓n✓ng✓g✓g✓gs✓s✓s✓s are represented literally by placing single quote marks around the characters making up the string. S✓S✓S✓St✓t✓t✓tr✓r✓r✓ri✓i✓i✓in✓n✓n✓ng✓g✓g✓gs✓s✓s✓s also differ from A✓A✓A✓Ar✓r✓r✓rr✓r✓r✓ra✓a✓a✓ay✓y✓y✓ys✓s✓s✓s in that Strings possess an ordering, given by the underlying ascii sequence. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓t_✓o , Concatenates the argument to the receiver string, producing a new string. If the argu- ment is not a S✓S✓S✓St✓t✓t✓tr✓r✓r✓ri✓i✓i✓in✓n✓n✓ng✓g✓g✓g it is first converted using _✓p_✓r_✓i_✓n_✓t_✓S_✓t_✓r_✓i_✓n_✓g. < The argument must be a S✓S✓S✓St✓t✓t✓tr✓r✓r✓ri✓i✓i✓in✓n✓n✓ng✓g✓g✓g. Test if the receiver is lexically less than the argument. For the purposes of comparison case differ- ences are ignored. <= Test if the receiver is lexically less than or equal to the argument. >= Test if the receiver is lexically greater than or equal to the argument. > Test if the receiver is lexically greater than the argument. _✓r asSymbol Return a S✓S✓S✓Sy✓y✓y✓ym✓m✓m✓mb✓b✓b✓bo✓o✓o✓ol✓l✓l✓l with characters given by the receiver string. at: Return the character stored at the position given by the argument. Produce and error mes- sage, and return n✓n✓n✓ni✓i✓i✓il✓l✓l✓l, if the argument does not represent a valid key. at:put: Store the character given by second argument at the location given by the first argument. Produce an error message, and return n✓n✓n✓ni✓i✓i✓il✓l✓l✓l, if either argument is invalid. _✓n copyFrom:length: Return a substring of the receiver. The sub- string is taken from the indicated starting position in the receiver and extends for the given length. Produce an error message, and return n✓n✓n✓ni✓i✓i✓il✓l✓l✓l, if the given positions are not class S✓S✓S✓St✓t✓t✓tr✓r✓r✓ri✓i✓i✓in✓n✓n✓ng✓g✓g✓g (continued) legal. _✓r copyFrom:to: Return a substring of the receiver. The sub- string is taken from the indicated positions. Produce an error message, and return n✓n✓n✓ni✓i✓i✓il✓l✓l✓l, if the given positions are not legal. _✓n printAt: The argument must be a P✓P✓P✓Po✓o✓o✓oi✓i✓i✓in✓n✓n✓nt✓t✓t✓t which describes a location on the terminal screen. The string is printed at the specified location. size Return the number of characters stored in the string. sameAs: Return true if the receiver and argument string match with the exception of case differences. Note that the boolean message = , inherited from ArrayedCollection, can be used to see if two strings are the same including case differences. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result 'example' at: 2 $x 'bead' at: 1 put: $r read 'small' > 'BIG' True 'small' sameAs: 'SMALL' True 'tary' sort arty 'Rats live on no evil Star' reversed ratS live on no evil staR Object B✓B✓B✓Bl✓l✓l✓lo✓o✓o✓oc✓c✓c✓ck✓k✓k✓k Although it is easy for the programmer to think of blocks as a syntactic construct, or a control structure, they are actually objects, and share attributes of all other objects in the Smalltalk system, such as the ability to respond to messages. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓t_✓o fork Start the block executing as a P✓P✓P✓Pr✓r✓r✓ro✓o✓o✓oc✓c✓c✓ce✓e✓e✓es✓s✓s✓ss✓s✓s✓s. The value n✓n✓n✓ni✓i✓i✓il✓l✓l✓l is immediately returned, and the P✓P✓P✓Pr✓r✓r✓ro✓o✓o✓oc✓c✓c✓ce✓e✓e✓es✓s✓s✓ss✓s✓s✓s created from the block is scheduled to run in parallel with the current process. forkWith: Similar to _✓f_✓o_✓r_✓k, except that the array is passed as arguments to the receiver block prior to scheduling for execution. newProcess A new P✓P✓P✓Pr✓r✓r✓ro✓o✓o✓oc✓c✓c✓ce✓e✓e✓es✓s✓s✓ss✓s✓s✓s is created for the block, but is not scheduled for execution. _✓n newProcessWith: Similar to _✓n_✓e_✓w_✓P_✓r_✓o_✓c_✓e_✓s_✓s, except that the array is passed as arguments to the receiver block prior to it being made into a process. value Evaluates the receiver block. Produces an error message, and returns nil, if the receiver block required arguments. Return the value yielded by the block. value: Evaluates the receiver block. Produces an error message, and returns nil, if the receiver block did not require a single argu- ment. Return the value yielded by the block. value:value: Two argument block evaluation. value:value:value: Three argument block evaluation. value:value:value:value: Four argument block evaluation. value:value:value:value:value: Five argument block evaluation. whileTrue: The receiver block is repeatedly evaluated. While it evaluates to true, the argument block is also evaluated. Return nil when the class B✓B✓B✓Bl✓l✓l✓lo✓o✓o✓oc✓c✓c✓ck✓k✓k✓k (continued) receiver block no longer evaluates to true. whileTrue The receiver block is repeatedly evaluated until it returns a value that is not true. whileFalse: The receiver block is repeatedly evaluated. While it evaluates to false, the argument block is also evaluated. Return nil when the receiver block no longer evaluates to false. whileFalse The receiver block is repeatedly evaluated until it returns a value that is not false. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result ['block indeed'] value block indeed [:x :y | x + y + 3] value: 5 value: 7 15 Object C✓C✓C✓Cl✓l✓l✓la✓a✓a✓as✓s✓s✓ss✓s✓s✓s The class C✓C✓C✓Cl✓l✓l✓la✓a✓a✓as✓s✓s✓ss✓s✓s✓s provides protocol for manipulating class instances. An instance of class C✓C✓C✓Cl✓l✓l✓la✓a✓a✓as✓s✓s✓ss✓s✓s✓s is generated for each class in the Smalltalk system. New instances of this class are then formed by sending messages to the class instance. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓t_✓o _✓n deepCopy: The argument must be an instance of the receiver class. A deepCopy of the argument is returned. _✓n edit The user is placed into a editor editing the file from which the class description was originally obtained. When the editor ter- minates, the class description will be reparsed and will override the previous description. See also _✓v_✓i_✓e_✓w (below). _✓n list Lists all subclasses of the given class recursively. In particular, O✓O✓O✓Ob✓b✓b✓bj✓j✓j✓je✓e✓e✓ec✓c✓c✓ct✓t✓t✓t _✓l_✓i_✓s_✓t will list the names of all the classes in the sys- tem. new A new instance of the receiver class is returned. If the methods for the receiver contain protocol for _✓n_✓e_✓w, the new instance will first be passed this message. new: A new instance of the receiver class is returned. If the methods for the receiver contain protocol for _✓n_✓e_✓w:, the new instance will first be passed this message. _✓n respondsTo List all the messages that the current class will respond to. _✓d respondsTo: The argument must be a Symbol. Return true if the receiver class, or any of its superc- lasses, contains a method for the indicated message. Return false otherwise. _✓n shallowCopy: The argument must be an instance of the receiver class. A shallowCopy of the argu- ment is returned. _✓n superClass Return the superclass of the receiver class. _✓n variables Return an array containing the names of the instance variables used in the receiver class C✓C✓C✓Cl✓l✓l✓la✓a✓a✓as✓s✓s✓ss✓s✓s✓s (continued) class. _✓n view Place the user into an editor viewing the class description from which the class was created. Changes made to the file will not, however, affect the current class representa- tion. _✓E_✓x_✓a_✓m_✓p_✓l_✓e_✓s Printed result Array new: 3 #( nil nil nil ) Bag respondsTo: #add: True SequenceableCollection superClass KeyedCollection Object P✓P✓P✓Pr✓r✓r✓ro✓o✓o✓oc✓c✓c✓ce✓e✓e✓es✓s✓s✓ss✓s✓s✓s Processes are created by the system, or by passing the message _✓n_✓e_✓w_✓P_✓r_✓o_✓c_✓e_✓s_✓s or _✓f_✓o_✓r_✓k to a block; they cannot be created directly by the user. _✓R_✓e_✓s_✓p_✓o_✓n_✓d_✓s _✓T_✓o block The receiver process is marked as being blocked. This is usually the result of a semaphore wait. Blocked processes are not executed. resume If the receiver process has been _✓s_✓u_✓s_✓p_✓e_✓n_✓ded, it is rescheduled for execution. suspend If the receiver process is scheduled for exe- cution, it is marked as suspended. Suspended processes are not executed. state The current state of the receiver process is returned as a Symbol. terminate The receiver process is terminated. Unlike a blocked or suspended process, a terminated process cannot be restarted. unblock If the receiver process is currently blocked, it is scheduled for execution. yield Returns n✓n✓n✓ni✓i✓i✓il✓l✓l✓l. As a side effect, however, if there are pending processes the current pro- cess is placed back on the process queue and another process started. 
