Shell::Perl(3pm)					User Contributed Perl Documentation					  Shell::Perl(3pm)

NAME

       Shell::Perl - A read-eval-print loop in Perl

SYNOPSYS

	   use Shell::Perl;
	   Shell::Perl->run_with_args;

DESCRIPTION

       This is the implementation of a command-line interpreter for Perl.  I wrote this because I was tired of using irb when needing a calculator
       with a real language within. Ah, that and because it was damn easy to write it.

       This module is the heart of the pirl script provided with Shell-Perl distribution, along with this module.

   EXAMPLE SESSION
	   $ pirl
	   Welcome to the Perl shell. Type ':help' for more information

	   pirl @> 1+1
	   2

	   pirl @> use YAML qw(Load Dump);
	   ()

	   pirl @> $data = Load("--- { a: 1, b: [ 1, 2, 3] }
");
	   { a => 1, b => [1, 2, 3] }

	   pirl @> $var = 'a 1 2 3'; $var =~ /(w+) (d+) (d+)/
	   ("a", 1, 2)

	   pirl @> :q

   COMMANDS
       Most of the time, the shell reads Perl statements, evaluates them and outputs the result.

       There are a few commands (started by ':') that are handled by the shell itself.

       :h(elp)
	   Handy for remembering what the shell commands are.

       :q(uit)
	   Leave the shell. The Perl statement "exit" will work too.

	   SYNONYMS: :exit, :x

       :set out (D|DD|DDS|Y|P)
	   Changes the dumper for the expression results used before output. The current supported are:

	   D   "Data::Dump"

	   DD  "Data::Dumper", the good and old core module

	   DDS "Data::Dump::Streamer"

	   Y   "YAML"

	   P   a plain dumper ("$ans" or "@ans")

	   When creating the shell, the dump format is searched among the available ones in the order "D", "DD", "DDS", "Y" and "P". That means
	   Data::Dump is preferred and will be used if available/installed. Otherwise, Data::Dumper is tried, and so on.

	   Read more about dumpers at Shell::Perl::Dumper.

       :set ctx (scalar|list|void|s|l|v|$|@|_)
	   Changes the default context used to evaluate the entered expression.  The default is 'list'.

	   Intuitively, 'scalar', 's' and '$' are synonyms, just like 'list', 'l', and '@' or 'void', 'v', '_'.

	   There is a nice way to override the default context in a given expression.  Just a '#' followed by one of
	   'scalar|list|void|s|l|v|$|@|_' at the end of the expression.

	       pirl @> $var = 'a 1 2 3'; $var =~ /(w+) (d+) (d+)/
	       ("a", 1, 2)

	       pirl @> $var = 'a 1 2 3'; $var =~ /(w+) (d+) (d+)/ #scalar
	       1

       :reset
	   Resets the environment, erasing the symbols created at the current evaluation package. See the section "ABOUT EVALUATION".

   METHODS
       Remember this is an alpha version, so the API may change and that includes the methods documented here. So consider this section as
       implementation notes for a while.

       In later versions, some of these information may be promoted to a public status. Others may be hidden or changed and even disappear without
       further notice.

       new
	       $sh = Shell::Version->new;

	   The constructor.

       run_with_args
	       Shell::Perl->run_with_args;

	   Starts the read-eval-print loop after reading options from @ARGV. It is a class method.

	   If an option -v or --version is provided, instead of starting the REPL, it prints the script identification and exits with 0.

	      $ pirl -v
	      This is pirl, version 0.0017 (bin/pirl, using Shell::Perl 0.0017)

       run
	       $sh->run;

	   The same as "run_with_args" but with no code for interpreting command-line arguments. It is an instance method, so that
	   "Shell::Perl-"run_with_args> is kind of:

	       Shell::Perl->new->run;

       eval
	       $answer = $sh->eval($exp);
	       @answer = $sh->eval($exp);

	   Evaluates the user input given in $exp as Perl code and returns the result. That is the 'eval' part of the read-eval-print loop.

       print
	       $sh->print(@args);

	   Prints a list of args at the output stream currently used by the shell.

       help
	       $sh->help;

	   Outputs the help as provided by the command ":help".

       reset
	       $sh->reset;

	   Does nothing by now, but it will.

       dump_history
	       $sh->dump_history();
	       $sh->dump_history($file);

	   Prints the readline history to "STDOUT" or the optional file.  Used to implement experimental command ":dump history".

	   This is experimental code and should change in the future.  More control should be added and integrated with other terminal features.

       set_ctx
	       $sh->set_ctx($context);

	   Assigns to the current shell context. The argument must be one of " ( 'scalar', 'list', 'void', 's', 'l', 'v', '$', '@', '_' ) ".

       set_package
	       $sh->set_package($package);

	   Changes current evaluation package. Doesn't change if the new package name is malformed.

       set_out
	       $sh->set_out($dumper);

	   Changes the current dumper used for printing the evaluation results. Actually must be one of "D" (for Data::Dump), "DD" (for
	   Data::Dumper), "DDS" (for Data::Dump::Streamer), "Y" (for YAML) or "P" (for plain string interpolation).

       prompt_title
	       $prompt = $sh->prompt_title;

	   Returns the current prompt which changes with executable name and context. For example, "pirl @>", "pirl $>", and "pirl >".

       quit
	       $sh->quit;

	   This method is invoked when these commands and statements are parsed by the REPL:

	       :q
	       :quit
	       :x
	       :exit
	       quit
	       exit

	   It runs the shutdown procedures for a smooth termination of the shell. For example, it saves the terminal history file.

GORY DETAILS

   ABOUT EVALUATION
       When the statement read is evaluated, this is done at a different package, which is "Shell::Perl::sandbox" by default.

       So:

	   $ perl -Mlib=lib bin/pirl
	   Welcome to the Perl shell. Type ':help' for more information

	   pirl @> $a = 2;
	   2

	   pirl @> :set out Y # output in YAML

	   pirl @> \%Shell::Perl::sandbox::
	   ---
	   BEGIN: !!perl/glob:
	     PACKAGE: Shell::Perl::sandbox
	     NAME: BEGIN
	   a: !!perl/glob:
	     PACKAGE: Shell::Perl::sandbox
	     NAME: a
	     SCALAR: 2

       This package serves as an environment for the current shell session and :reset can wipe it away.

	   pirl @> :reset

	   pirl @> \%Shell::Perl::sandbox::
	   ---
	   BEGIN: !!perl/glob:
	     PACKAGE: Shell::Perl::sandbox
	     NAME: BEGIN

TO DO

       There is a lot to do, as always. Some of the top priority tasks are:

       o   Accept multiline statements;.

       o   Refactor the code to promote easy customization of features.

SEE ALSO

       This project is hosted at Google Code:

	   http://code.google.com/p/iperl/

       To know about interactive Perl interpreters, there are two FAQS contained in perlfaq3 which are good starting points.  Those are

	   How can I use Perl interactively?
	   http://perldoc.perl.org/perlfaq3.html#How-can-I-use-Perl-interactively%3f

	   Is there a Perl shell?
	   http://perldoc.perl.org/perlfaq3.html#How-can-I-use-Perl-interactively%3f

       An extra list of Perl shells can be found here:

	   http://www.focusresearch.com/gregor/document/psh-1.1.html#other_perl_shells

BUGS

       It is a one-line evaluator by now.

       I don't know what happens if you eval within an eval.  I don't expect good things to come. (Lorn who prodded me about this will going to
       find it out and then I will tell you.)

       There are some quirks with Term::Readline (at least on Windows).

       There are more bugs. I am lazy to collect them all and list them now.

       Please report bugs via CPAN RT <http://rt.cpan.org/NoAuth/Bugs.html?Dist=Shell-Perl> or <mailto://bugs-Shell-Perl@rt.cpan.org>.

AUTHORS

       Adriano R. Ferreira, <ferreira@cpan.org>

       Caio Marcelo, <cmarcelo@gmail.com>

COPYRIGHT AND LICENSE

       Copyright (C) 2007aXX2011 by Adriano R. Ferreira

       This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

perl v5.10.1							    2011-03-13							  Shell::Perl(3pm)