text: Devel::REPL::Overview - overview of Devel::REPL.
  Most modern languages have consoles. The console is an interactive tool that evaluates your input while you type it. It gives you several advantages:
  For Ruby it would be irb, for Python is... python by itself and for perl... and there was nothing for perl (except that ugly perl -d -e "" and several failed projects) until Devel::REPL was written by Matt S Trout (a.k.a. mst) from ShadowCatSystems.
  REPL stands for Read, Evaluate, Print, Loop. Lets install and try it.
  $ cpan Devel::REPL
  After installation you have a lot of new modules, but the most interesting things are:
  And a bunch of plugins (I'll describe them later). In command line type:
  $ re.pl
  If everything is ok you'll see a prompt (underlined $). That's it. You can start typing expressions.
  An example session:
  $ sub factorial { > my $number = shift; > return $number > 1 ? $number * factorial($number-1) : $number; > } $ factorial 1 # by the way, comments are allowed 1 # our return value $ factorial 5 120 $ [1,2,3,4,5,6,7] $ARRAY1 = [ 1, 2, 3, # return values are printed with Data::Dumper::Streamer. 4, # See Plugins section 5, 6, 7 ]; $ {apple=>1,fruit=>'apple',cart=>['apple','banana']} $HASH1 = { apple => 1, cart => [ 'apple', 'banana' ], fruit => 'apple' }; $ package MyPackage; # create a package $ sub say_hi { # define a sub > print "Hi!\n"; > } # statement is evaluated only after we've finished typing block. # See Plugins section. > __PACKAGE__ MyPackage > package main; > __PACKAGE_ main > MyPackage->say_hi Hi! 1 $
  Devel::REPL has a control files feature. Control files are evaluated on session start in the same way as you would type them manually in the console.
  The default control file is located at $HOME/.re.pl/repl.rc.
  You can store there any statements you would normally type in.
  I.e. my $HOME/.re.pl/repl.rc has next lines:
  use feature 'say'; # to don't write \n all the time use Data::Dumper; # pretty print data structures sub pp { print Data::Dumper->Dump([@_]) }
  You can have multiple control files and they can be anywhere in the file system. To make re.pl use some rc-file other than repl.rc, call it like this:
  $ re.pl --rcfile /path/to/your/rc.file
  If your rc-file is in $HOME/.re.pl directory, you can omit the path:
  $ re.pl --rcfile rc.file
  If you have rc-file with the same name in current directory and you don't want to type path, you can:
  $ re.pl --rcfile ./rc.file
  Plugins extend functionality and change behavior of Devel::REPL. Bundled plugins are:
  $ sub mysub { > print "Hello, World!\n"; ## notice prompt change > } $ mysub Hello, World! 1 $ but this *doesn't* mean you can print sub name or identifier on several lines. Don't do that! It won't work.
  There are lots of contributed plugins you can find at CPAN.
  If plugins change and extend functionality of Devel::REPL, profiles are changing your environment (loaded plugins, constants, subs and etc.).
  For example, the Minimal profile, Devel::REPL::Profile::Minimal:
  package Devel::REPL::Profile::Minimal; use Moose; ### advanced OOP system for Perl ### keep those exports/imports out of our namespace use namespace::autoclean; with 'Devel::REPL::Profile'; ## seem perldoc Muse sub plugins { ### plugins we want to be loaded qw(History LexEnv DDS Packages Commands MultiLine::PPI); } ### the only required sub for profile, ### it is called on profile activation sub apply_profile { my ($self, $repl) = @_; ### $self - no comments, $repl - current instance of Devel::REPL $repl->load_plugin($_) for $self->plugins; ### load our plugins } 1;
  There is also the StandardDevel::REPL::Profile::Standard profile, which contains a number of optional (yet very useful) features.
  To enable some profile use the
  --profile switch:
  $ re.pl --profile SomeProfile
  Alternatively, you can set the environment variable
  DEVEL_REPL_PROFILE to
  SomeProfile, or set the
  profile key in your
  rcfile (see Devel::REPL for more information).