CP/M/CPM_CDROM.iso/jsage/zsus/z3help/v.lbr/VALIAS.HZP/VALIAS.HLP

Text File | 1991-11-18 | 9.9 KB | 201 lines

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                                 VALIAS.COM                                   

             Size (recs) CRC   Version    Author/Latest Issue      Disk
               7k (49)   B204  0.2b       Jay Sage                 Z3COM10


  1- Syntax  2- Recursive Aliases  3- Commands                                

     VALIAS is a program for  creating new  and editing existing alias program
files.  It uses the full-screen capabilities provided by the Z3 TCAP (terminal
capability) facility to make it  much easier to create and edit alias scripts.
Support  for  clear screen,  clear-to-end-of-line,  and  cursor  addressing is
required.

     Once VALIAS is running,  it presents prompts to the user at the bottom of
the screen  and status information  at  the top of  the screen,  including the
program name  VALIAS and the version number,  the alias mode,  and the default
alias file name in use.  The middle 20 lines of the screen show the individual
commands of a prototype command line.
:1

   
Syntax:  VALIAS [[DIR:]FILENAME]

     If VALIAS is invoked with a file name specified,  a file of that name and
type COM will be  read in if it exists and if it is an alias file.   If such a
file does not exist or is not  an alias file,  then the specified name will be
used as the default output file for the creation of a new alias.   An optional
directory in either  DU  or  DIR  form may  be specified.   If  a file type is
included with the name,  it will be ignored and replaced by COM.   If the file
name is ambiguous, VALIAS will use the first matching file found.

   The user may enter  lines with  leading blanks to make  the alias easier to
read  (especially useful for keeping IF levels straight)  and may put multiple
commands separated  by semicolons on a single line.   When  the alias file  is
created,  leading blanks  are removed  and  the lines are concatenated  into a
single multiple command line.   The VALIAS Format command  (see below) will do
this and then redisplay the commands one per line.   If there are more than 20
commands, the 20th line will include the excess commands.
:2


Recursive Aliases:

   With VALIAS a new type  of alias file has been introduced.   A normal alias
expands the  prototype  command  line  stored  in  it  by performing parameter
substitution.  It  then  appends  any  commands  in  the multiple command line
buffer that appear after the  alias invocation and writes  the result into the
command  line buffer.   The type  of alias called recursive in VALIAS performs
the  same command line expansion,  but it flushes any other commands that were
in  the command line  buffer.  This is  useful  when an alias calls  itself or
another alias recursively so that  commands that  were not needed do not build
up in the command line after the alias and result in an overflow error.


   Consider the schematic alias WORK with the following command sequence:

                   EDIT $1.MAC
                   ASSEMBLE $1
                   IF ERROR
                     WORK $1
                   ELSE
                     LINK $1
                   FI

If the  edited  file  assembles  with  no errors,  the  sequence flows through
directly.   If assembly errors do occur,  however,  the alias is reinvoked.  A
normal  alias  would still append the expansion of  "ELSE;LINK $1;FI"  to  the
newly invoked alias.   Every cycle would  add  another copy of these commands.
Not only might these superfluous commands cause a command line overflow error,
but their execution would not even be wanted.  The recursive type alias solves
this problem.



   For the technically curious,  recursive aliases are implemented as follows.
The  file VALIAS1.COM into which the prototype  command line is placed to form
the alias  contains  a  flag  near the beginning of the code  (just before the
label START)  that determines whether the  command line will be flushed later.
A byte with an 'F' precedes this flag to identify the alias  as one of the new
type.   When VALIAS  reads in an existing alias for editing,  it can determine
whether it is of the new  (VALIAS1) or old (ALIAS1) type,  and if it is of the
new type it determines the mode (normal or recursive) and sets the VALIAS flag
to match.  Old type aliases default to normal type.
:3


VALIAS Commands:


   The main VALIAS command prompt at the  bottom of  the screen  waits for the
user to  press one of  the following keys and  then performs the corresponding
function.



VALIAS Commands:  C

   Clear all commands  and  begin entry  of  new  commands at line A in insert
mode.  The default alias name is not changed.



VALIAS Commands:  D

   Delete a line in the alias.   The user will be prompted for the name of the
line  to  delete (A-T).   A carriage  return  or  control- c  will  cancel the
operation;  entering  a  letter between  A  and  T in upper or lower case will
remove that line and close up the space; any other response will be ignored.




VALIAS Commands:  F

   Format  the  command lines,  removing leading spaces on each line and empty
lines between commands and redisplaying the commands one per line.



VALIAS Commands:  H

   Help  information is displayed  at the lower right portion of the screen if
VALIAS  was assembled  with the HCMDFL  (help command flag)  set  to yes.   We
recommend  not including  this command because  it pushes  VALIAS  over the 6K
boundary and because the  commands  are self-explanatory once  they have  been
learned.   We included this  command mainly for the beta-test versions,  which
were distributed without a DOC file.



VALIAS Commands:  I

   Insert new command lines.   This command  prompts the  user for the command
line BEFORE WHICH to  begin inserting  additional  commands.  After  the  user
answers  the prompt  as with the D command,  a blank line is opened up for the
insertion at the indicated location and the cursor is placed there.  After the
new command is ended with a carriage return,  another blank line after the one
just entered is opened.  This process continues until an empty line is entered
or until the last  or next to last line is reached.   Then the extra open line
is closed and the user is returned to the command prompt.  Existing contiguous
commands on  lines above the insertion line  are pushed  up  by one line after
each insertion.   To prevent losing the last line,  VALIAS won't automatically
advance  to the last line unless that line is currently empty  (if you specify
the last line for an insert,  the last line will be lost).  Note that commands
do not  have to be on contiguous lines;  empty lines  may exist between filled
lines.   When the alias file is created,  these blank lines  will be closed up
automatically.  We encourage you to leave blank lines to make the structure of
the alias clearer during creation.



VALIAS Commands:  L

   Load an existing alias from disk or establish a new default name.  The user
will be  prompted  for the  name of  the alias file.   If a default name is in
effect as a result of a previous load or save command or as a result of a file
name included  when VALIAS was invoked,  then entering  a carriage return will
select this name.   A new name with an optional directory specification of the
DU or DIR form may be given.   To cancel the load command,  enter  a control-A
and a carriage return.  If a file type is specified, it will be ignored; if an
ambiguous file name is given, the matching directory entry will be used.  Once
a file has been specified, the commands will be cleared and VALIAS will try to
load  the  specified  file.  The load  is  performed  exactly  as  with a name
specified on the command line when VALIAS was invoked (the same code is used).



VALIAS Commands:  M

   Mode selection.  This  command  sets  the  mode  to  create  a normal  or a
recursive type alias file.  See the discussion of recursive aliases above.   A
mode remains in effect until  changed  by the M command or by the loading of a
new file.  The default mode is normal.



VALIAS Commands:  R

   Replace a command.  The user will be prompted for a line to work on as with
the D command.   When  a valid  line has  been selected,  the existing command
there  (if any) is deleted,  and the cursor is placed on the line to allow the
user to enter  a replacement command.   Note that the replacement command  may
consist  of several commands separated by semicolons (no semicolon at the very
end, however).   Also note that  the replacement can be done at any line,  not
only where a command existed previously or next to one.  Isolated lines can be
entered at any line.



VALIAS Commands:  S

   Save the commands into an alias file.   The user will  be prompted for  the
name of the alias file.  If a  default name  is  in effect  as  a result of  a
previous load or save  command or  as  a result of  a file name  included when
VALIAS was invoked, then entering  a carriage return will select this name.  A
new name with an optional directory specification of the DU or DIR form may be
given.   To cancel the save command,  enter a control-A and a carriage return.
If a file type is specified,  it will be ignored; if an ambiguous file name is
given,  the bell will ring and the prompt will be repeated.   If a file of the
given name exists,  the user will be asked if it should be overwritten.   When
the S command is completed,  the user returns to command mode to allow further
editing  of the commands.   In this  way multiple aliases can  be  created and
edited in a single session.



VALIAS Commands:  X


   eXit from VALIAS.   This command  or  control-c entered in response  to the
main command prompt of VALIAS will terminate the session and return to ZCPR3.
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