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Devel::REPL - a modern perl interactive shell
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my $repl = Devel::REPL->new;
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$repl->load_plugin($_) for qw(History LexEnv);
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Alternatively, use the 're.pl' script installed with the distribution
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This is an interactive shell for Perl, commonly known as a REPL - Read,
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Evaluate, Print, Loop. The shell provides for rapid development or testing
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of code without the need to create a temporary source code file.
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Through a plugin system, many features are available on demand. You can also
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tailor the environment through the use of profiles and run control files, for
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example to pre-load certain Perl modules when working on a particular project.
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To start a shell, follow one of the examples in the ["SYNOPSIS"](#synopsis) above.
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Once running, the shell accepts and will attempt to execute any code given. If
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the code executes successfully you'll be shown the result, otherwise an error
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message will be returned. Here are a few examples:
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$_ print "Hello, world!\n"
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Compile error: Bareword "nosuchfunction" not allowed while "strict subs" in use at (eval 130) line 5.
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In the first example above you see the output of the command (`Hello,
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world!`), if any, and then the return value of the statement (`1`). Following
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that example, an error is returned when the execution of some code fails.
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Note that the lack of semicolon on the end is not a mistake - the code is
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run inside a Block structure (to protect the REPL in case the code blows up),
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which means a single statement doesn't require the semicolon. You can add one
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If you followed the first example in the ["SYNOPSIS"](#synopsis) above, you'll have the
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[History](https://metacpan.org/pod/Devel::REPL::Plugin::History) and [LexEnv](https://metacpan.org/pod/Devel::REPL::Plugin::LexEnv)
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plugins loaded (and there are many more available).
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Although the shell might support "up-arrow" history, the History plugin adds
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"bang" history to that so you can re-execute chosen commands (with e.g.
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`!53`). The LexEnv plugin ensures that lexical variables declared with the
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`my` keyword will automatically persist between statements executed in the
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When you `use` any Perl module, the `import()` will work as expected - the
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exported functions from that module are available for immediate use:
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$_ carp "I'm dieeeing!\n"
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String found where operator expected at (eval 129) line 5, near "carp "I'm dieeeing!\n""
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(Do you need to predeclare carp?)
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Compile error: syntax error at (eval 129) line 5, near "carp "I'm dieeeing!\n""
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BEGIN not safe after errors--compilation aborted at (eval 129) line 5.
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$_ carp "I'm dieeeing!\n"
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at /usr/share/perl5/Lexical/Persistence.pm line 327
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To quit from the shell, hit `Ctrl+D` or `Ctrl+C`.
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MSWin32 NOTE: control keys won't work if TERM=dumb
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because readline functionality will be disabled.
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For particular projects you might well end up running the same commands each
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time the REPL shell starts up - loading Perl modules, setting configuration,
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and so on. A run control file lets you have this done automatically, and you
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can have multiple files for different projects.
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By default the `re.pl` program looks for `$HOME/.re.pl/repl.rc`, and
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runs whatever code is in there as if you had entered it at the REPL shell
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To set a new run control file that's also in that directory, pass it as a
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system$ re.pl --rcfile myproject.pc
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If the filename happens to contain a forward slash, then it's used absolutely,
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or realive to the current working directory:
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system$ re.pl --rcfile /path/to/my/project/repl.rc
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Within the run control file you might want to load plugins. This is covered in
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["The REPL shell object"](#the-repl-shell-object) section, below.
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To allow for the sharing of run control files, you can fashion them into a
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Perl module for distribution (perhaps via the CPAN). For more information on
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this feature, please see the [Devel::REPL::Profile](https://metacpan.org/pod/Devel::REPL::Profile) manual page.
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A `Standard` profile ships with `Devel::REPL`; it loads the following plugins
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(note that some of these require optional features -- or you can also use the
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- [Devel::REPL::Plugin::History](https://metacpan.org/pod/Devel::REPL::Plugin::History)
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- [Devel::REPL::Plugin::LexEnv](https://metacpan.org/pod/Devel::REPL::Plugin::LexEnv)
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- [Devel::REPL::Plugin::DDS](https://metacpan.org/pod/Devel::REPL::Plugin::DDS)
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- [Devel::REPL::Plugin::Packages](https://metacpan.org/pod/Devel::REPL::Plugin::Packages)
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- [Devel::REPL::Plugin::Commands](https://metacpan.org/pod/Devel::REPL::Plugin::Commands)
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- [Devel::REPL::Plugin::MultiLine::PPI](https://metacpan.org/pod/Devel::REPL::Plugin::MultiLine::PPI)
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- [Devel::REPL::Plugin::Colors](https://metacpan.org/pod/Devel::REPL::Plugin::Colors)
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- [Devel::REPL::Plugin::Completion](https://metacpan.org/pod/Devel::REPL::Plugin::Completion)
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- [Devel::REPL::Plugin::CompletionDriver::INC](https://metacpan.org/pod/Devel::REPL::Plugin::CompletionDriver::INC)
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- [Devel::REPL::Plugin::CompletionDriver::LexEnv](https://metacpan.org/pod/Devel::REPL::Plugin::CompletionDriver::LexEnv)
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- [Devel::REPL::Plugin::CompletionDriver::Keywords](https://metacpan.org/pod/Devel::REPL::Plugin::CompletionDriver::Keywords)
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- [Devel::REPL::Plugin::CompletionDriver::Methods](https://metacpan.org/pod/Devel::REPL::Plugin::CompletionDriver::Methods)
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- [Devel::REPL::Plugin::ReadlineHistory](https://metacpan.org/pod/Devel::REPL::Plugin::ReadlineHistory)
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Plugins are a way to add functionality to the REPL shell, and take advantage of
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`Devel::REPL` being based on the [Moose](https://metacpan.org/pod/Moose) object system for Perl 5. This
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means it's simple to 'hook into' many steps of the R-E-P-L process. Plugins
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can change the way commands are interpreted, or the way their results are
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output, or even add commands to the shell environment.
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A number of plugins ship with `Devel::REPL`, and more are available on the
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CPAN. Some of the shipped plugins are loaded in the default profile, mentioned
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above. These plugins can be loaded in your ` $HOME/.re.pl/repl.rc ` like:
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load_plugin qw( CompletionDriver::Global DumpHistory );
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Writing your own plugins is not difficult, and is discussed in the
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[Devel::REPL::Plugin](https://metacpan.org/pod/Devel::REPL::Plugin) manual page, along with links to the manual pages of
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all the plugins shipped with `Devel::REPL`.
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## The REPL shell object
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From time to time you'll want to interact with or manipulate the
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`Devel::REPL` shell object itself; that is, the instance of the shell you're
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The object is always available through the `$_REPL` variable. One common
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requirement is to load an additional plugin, after your profile and run
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control files have already been executed:
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$_ $_REPL->load_plugin('Timing');
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$_ print "Hello again, world!\n"
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Took 0.00148296356201172 seconds.
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In addition to the prerequisites declared in this distribution, which should be automatically installed by your [CPAN](https://metacpan.org/pod/CPAN) client, there are a number of optional features, used by
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additional plugins. You can install any of these features by installing this
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distribution interactively (e.g. `cpanm --interactive Devel::REPL`).
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- Completion plugin - extensible tab completion
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- DDS plugin - better format results with Data::Dump::Streamer
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- DDC plugin - even better format results with Data::Dumper::Concise
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- INC completion driver - tab complete module names in use and require
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- Interrupt plugin - traps SIGINT to kill long-running lines
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- Keywords completion driver - tab complete Perl keywords and operators
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- LexEnv plugin - variables declared with "my" persist between statements
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- MultiLine::PPI plugin - continue reading lines until all blocks are closed
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- Nopaste plugin - upload a session\\'s input and output to a Pastebin
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- PPI plugin - PPI dumping of Perl code
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- Refresh plugin - automatically reload libraries with Module::Refresh
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Matt S Trout - mst (at) shadowcatsystems.co.uk ([http://www.shadowcatsystems.co.uk/](http://www.shadowcatsystems.co.uk/))
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- Stevan Little - stevan (at) iinteractive.com
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- Alexis Sukrieh - sukria+perl (at) sukria.net
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- mgrimes - mgrimes (at) cpan dot org
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- Shawn M Moore - sartak (at) gmail.com
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- Oliver Gorwits - oliver on irc.perl.org
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- Andrew Moore - `<amoore@cpan.org>`
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- Norbert Buchmuller `<norbi@nix.hu>`
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- Dave Houston `<dhouston@cpan.org>`
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- Karen Etheridge `<ether@cpan.org>`
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This library is free software under the same terms as perl itself
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README.md
