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- =head1 NAME
-
- version - Perl extension for Version Objects
-
- =head1 SYNOPSIS
-
- # Parsing version strings (decimal or dotted-decimal)
-
- use version 0.77; # get latest bug-fixes and API
- $ver = version->parse($string)
-
- # Declaring a dotted-decimal $VERSION (keep on one line!)
-
- use version 0.77; our $VERSION = version->declare("v1.2.3"); # formal
- use version 0.77; our $VERSION = qv("v1.2.3"); # shorthand
- use version 0.77; our $VERSION = qv("v1.2_3"); # alpha
-
- # Declaring an old-style decimal $VERSION (use quotes!)
-
- use version 0.77; our $VERSION = version->parse("1.0203"); # formal
- use version 0.77; our $VERSION = version->parse("1.02_03"); # alpha
-
- # Comparing mixed version styles (decimals, dotted-decimals, objects)
-
- if ( version->parse($v1) == version->parse($v2) ) {
- # do stuff
- }
-
- # Sorting mixed version styles
-
- @ordered = sort { version->parse($a) <=> version->parse($b) } @list;
-
- =head1 DESCRIPTION
-
- Version objects were added to Perl in 5.10. This module implements version
- objects for older version of Perl and provides the version object API for all
- versions of Perl. All previous releases before 0.74 are deprecated and should
- not be used due to incompatible API changes. Version 0.77 introduces the new
- 'parse' and 'declare' methods to standardize usage. You are strongly urged to
- set 0.77 as a minimum in your code, e.g.
-
- use version 0.77; # even for Perl v.5.10.0
-
- =head1 TYPES OF VERSION OBJECTS
-
- There are two different types of version objects, corresponding to the two
- different styles of versions in use:
-
- =over 2
-
- =item Decimal Versions
-
- The classic floating-point number $VERSION. The advantage to this style is
- that you don't need to do anything special, just type a number (without
- quotes) into your source file.
-
- =item Dotted Decimal Versions
-
- The more modern form of version assignment, with 3 (or potentially more)
- integers seperated by decimal points (e.g. v1.2.3). This is the form that
- Perl itself has used since 5.6.0 was released. The leading "v" is now
- strongly recommended for clarity, and will throw a warning in a future
- release if omitted.
-
- =back
-
- See L<VERSION OBJECT DETAILS> for further information.
-
- =head1 DECLARING VERSIONS
-
- If you have a module that uses a decimal $VERSION (floating point), and you
- do not intend to ever change that, this module is not for you. There is
- nothing that version.pm gains you over a simple $VERSION assignment:
-
- our $VERSION = 1.02;
-
- Since Perl v5.10.0 includes the version.pm comparison logic anyways,
- you don't need to do anything at all.
-
- =head2 How to convert a module from decimal to dotted-decimal
-
- If you have used a decimal $VERSION in the past and wish to switch to a
- dotted-decimal $VERSION, then you need to make a one-time conversion to
- the new format.
-
- B<Important Note>: you must ensure that your new $VERSION is numerically
- greater than your current decimal $VERSION; this is not always obvious. First,
- convert your old decimal version (e.g. 1.02) to a normalized dotted-decimal
- form:
-
- $ perl -Mversion -e 'print version->parse("1.02")->normal'
- v1.20.0
-
- Then increment any of the dotted-decimal components (v1.20.1 or v1.21.0).
-
- =head2 How to C<declare()> a dotted-decimal version
-
- use version 0.77; our $VERSION = version->declare("v1.2.3");
-
- The C<declare()> method always creates dotted-decimal version objects. When
- used in a module, you B<must> put it on the same line as "use version" to
- ensure that $VERSION is read correctly by PAUSE and installer tools. You
- should also add 'version' to the 'configure_requires' section of your
- module metadata file. See instructions in L<ExtUtils::MakeMaker> or
- L<Module::Build> for details.
-
- B<Important Note>: Even if you pass in what looks like a decimal number
- ("1.2"), a dotted-decimal will be created ("v1.200.0"). To avoid confusion
- or unintentional errors on older Perls, follow these guidelines:
-
- =over 2
-
- =item *
-
- Always use a dotted-decimal with (at least) three components
-
- =item *
-
- Always use a leading-v
-
- =item *
-
- Always quote the version
-
- =back
-
- If you really insist on using version.pm with an ordinary decimal version,
- use C<parse()> instead of declare. See the L<PARSING AND COMPARING VERSIONS>
- for details.
-
- See also L<VERSION OBJECT DETAILS> for more on version number conversion,
- quoting, calculated version numbers and declaring developer or "alpha" version
- numbers.
-
- =head1 PARSING AND COMPARING VERSIONS
-
- If you need to compare version numbers, but can't be sure whether they are
- expressed as numbers, strings, v-strings or version objects, then you can
- use version.pm to parse them all into objects for comparison.
-
- =head2 How to C<parse()> a version
-
- The C<parse()> method takes in anything that might be a version and returns
- a corresponding version object, doing any necessary conversion along the way.
-
- =over 2
-
- =item *
-
- Dotted-decimal: bare v-strings (v1.2.3) and strings with more than one
- decimal point and a leading 'v' ("v1.2.3"); NOTE you can technically use a
- v-string or strings with a leading-v and only one decimal point (v1.2 or
- "v1.2"), but you will confuse both yourself and others.
-
- =item *
-
- Decimal: regular decimal numbers (literal or in a string)
-
- =back
-
- Some examples:
-
- $variable version->parse($variable)
- --------- -------------------------
- 1.23 v1.230.0
- "1.23" v1.230.0
- v1.23 v1.23.0
- "v1.23" v1.23.0
- "1.2.3" v1.2.3
- "v1.2.3" v1.2.3
-
- See L<VERSION OBJECT DETAILS> for more on version number conversion.
-
- =head2 How to compare version objects
-
- Version objects overload the C<cmp> and C<< E<lt>=E<gt> >> operators. Perl
- automatically generates all of the other comparison operators based on those
- two so all the normal logical comparisons will work.
-
- if ( version->parse($v1) == version->parse($v2) ) {
- # do stuff
- }
-
- If a version object is compared against a non-version object, the non-object
- term will be converted to a version object using C<parse()>. This may give
- surprising results:
-
- $v1 = version->parse("v0.95.0");
- $bool = $v1 < 0.96; # FALSE since 0.96 is v0.960.0
-
- Always comparing to a version object will help avoid surprises:
-
- $bool = $v1 < version->parse("v0.96.0"); # TRUE
-
- =head1 VERSION OBJECT DETAILS
-
- =head2 Equivalence between Decimal and Dotted-Decimal Versions
-
- When Perl 5.6.0 was released, the decision was made to provide a
- transformation between the old-style decimal versions and new-style
- dotted-decimal versions:
-
- 5.6.0 == 5.006000
- 5.005_04 == 5.5.40
-
- The floating point number is taken and split first on the single decimal
- place, then each group of three digits to the right of the decimal makes up
- the next digit, and so on until the number of significant digits is exhausted,
- B<plus> enough trailing zeros to reach the next multiple of three.
-
- This was the method that version.pm adopted as well. Some examples may be
- helpful:
-
- equivalent
- decimal zero-padded dotted-decimal
- ------- ----------- --------------
- 1.2 1.200 v1.200.0
- 1.02 1.020 v1.20.0
- 1.002 1.002 v1.2.0
- 1.0023 1.002300 v1.2.300
- 1.00203 1.002030 v1.2.30
- 1.002003 1.002003 v1.2.3
-
- =head2 Quoting rules
-
- Because of the nature of the Perl parsing and tokenizing routines,
- certain initialization values B<must> be quoted in order to correctly
- parse as the intended version, especially when using the L<declare> or
- L<qv> methods. While you do not have to quote decimal numbers when
- creating version objects, it is always safe to quote B<all> initial values
- when using version.pm methods, as this will ensure that what you type is
- what is used.
-
- Additionally, if you quote your initializer, then the quoted value that goes
- B<in> will be be exactly what comes B<out> when your $VERSION is printed
- (stringified). If you do not quote your value, Perl's normal numeric handling
- comes into play and you may not get back what you were expecting.
-
- If you use a mathematic formula that resolves to a floating point number,
- you are dependent on Perl's conversion routines to yield the version you
- expect. You are pretty safe by dividing by a power of 10, for example,
- but other operations are not likely to be what you intend. For example:
-
- $VERSION = version->new((qw$Revision: 1.4)[1]/10);
- print $VERSION; # yields 0.14
- $V2 = version->new(100/9); # Integer overflow in decimal number
- print $V2; # yields something like 11.111.111.100
-
- Perl 5.8.1 and beyond are able to automatically quote v-strings but
- that is not possible in earlier versions of Perl. In other words:
-
- $version = version->new("v2.5.4"); # legal in all versions of Perl
- $newvers = version->new(v2.5.4); # legal only in Perl >= 5.8.1
-
- =head2 What about v-strings?
-
- There are two ways to enter v-strings: a bare number with two or more
- decimal points, or a bare number with one or more decimal points and a
- leading 'v' character (also bare). For example:
-
- $vs1 = 1.2.3; # encoded as \1\2\3
- $vs2 = v1.2; # encoded as \1\2
-
- However, the use of bare v-strings to initialize version objects is
- B<strongly> discouraged in all circumstances. Also, bare
- v-strings are not completely supported in any version of Perl prior to
- 5.8.1.
-
- If you insist on using bare v-strings with Perl > 5.6.0, be aware of the
- following limitations:
-
- 1) For Perl releases 5.6.0 through 5.8.0, the v-string code merely guesses,
- based on some characteristics of v-strings. You B<must> use a three part
- version, e.g. 1.2.3 or v1.2.3 in order for this heuristic to be successful.
-
- 2) For Perl releases 5.8.1 and later, v-strings have changed in the Perl
- core to be magical, which means that the version.pm code can automatically
- determine whether the v-string encoding was used.
-
- 3) In all cases, a version created using v-strings will have a stringified
- form that has a leading 'v' character, for the simple reason that sometimes
- it is impossible to tell whether one was present initially.
-
- =head2 Alpha versions
-
- For module authors using CPAN, the convention has been to note unstable
- releases with an underscore in the version string. (See L<CPAN>.) version.pm
- follows this convention and alpha releases will test as being newer than the
- more recent stable release, and less than the next stable release. For
- dotted-decimal versions, only the last element may be separated by an
- underscore:
-
- # Declaring
- use version 0.77; our $VERSION = version->declare("v1.2_3");
-
- # Parsing
- $v1 = version->parse("v1.2_3");
- $v1 = version->parse("1.002_003");
-
- =head1 OBJECT METHODS
-
- =head2 is_alpha()
-
- True if and only if the version object was created with a underscore, e.g.
-
- version->parse('1.002_03')->is_alpha; # TRUE
- version->declare('1.2.3_4')->is_alpha; # TRUE
-
- =head2 is_qv()
-
- True only if the version object is a dotted-decimal version, e.g.
-
- version->parse('v1.2.0')->is_qv; # TRUE
- version->declare('v1.2')->is_qv; # TRUE
- qv('1.2')->is_qv; # TRUE
- version->parse('1.2')->is_qv; # FALSE
-
- =head2 normal()
-
- Returns a string with a standard 'normalized' dotted-decimal form with a
- leading-v and at least 3 components.
-
- version->declare('v1.2')->normal; # v1.2.0
- version->parse('1.2')->normal; # v1.200.0
-
- =head2 numify()
-
- Returns a value representing the object in a pure decimal form without
- trailing zeroes.
-
- version->declare('v1.2')->numify; # 1.002
- version->parse('1.2')->numify; # 1.2
-
- =head2 stringify()
-
- Returns a string that is as close to the original representation as possible.
- If the original representation was a numeric literal, it will be returned the
- way perl would normally represent it in a string. This method is used whenever
- a version object is interpolated into a string.
-
- version->declare('v1.2')->stringify; # v1.2
- version->parse('1.200')->stringify; # 1.200
- version->parse(1.02_30)->stringify; # 1.023
-
- =head1 EXPORTED FUNCTIONS
-
- =head2 qv()
-
- This function is no longer recommended for use, but is maintained for
- compatibility with existing code. If you do not want to have it exported
- to your namespace, use this form:
-
- use version 0.77 ();
-
- =head1 AUTHOR
-
- John Peacock E<lt>jpeacock@cpan.orgE<gt>
-
- =head1 SEE ALSO
-
- L<version::Internal>.
-
- L<perl>.
-
- =cut
-