3 Devel::REPL - a modern perl interactive shell
11 my $repl = Devel::REPL->new;
12 $repl->load_plugin($_) for qw(History LexEnv);
15 Alternatively, use the 're.pl' script installed with the distribution
21 This is an interactive shell for Perl, commonly known as a REPL - Read,
22 Evaluate, Print, Loop. The shell provides for rapid development or testing
23 of code without the need to create a temporary source code file.
25 Through a plugin system, many features are available on demand. You can also
26 tailor the environment through the use of profiles and run control files, for
27 example to pre-load certain Perl modules when working on a particular project.
31 To start a shell, follow one of the examples in the ["SYNOPSIS"](#synopsis) above.
33 Once running, the shell accepts and will attempt to execute any code given. If
34 the code executes successfully you'll be shown the result, otherwise an error
35 message will be returned. Here are a few examples:
37 $_ print "Hello, world!\n"
41 Compile error: Bareword "nosuchfunction" not allowed while "strict subs" in use at (eval 130) line 5.
45 In the first example above you see the output of the command (`Hello,
46 world!`), if any, and then the return value of the statement (`1`). Following
47 that example, an error is returned when the execution of some code fails.
49 Note that the lack of semicolon on the end is not a mistake - the code is
50 run inside a Block structure (to protect the REPL in case the code blows up),
51 which means a single statement doesn't require the semicolon. You can add one
54 If you followed the first example in the ["SYNOPSIS"](#synopsis) above, you'll have the
55 [History](https://metacpan.org/pod/Devel::REPL::Plugin::History) and [LexEnv](https://metacpan.org/pod/Devel::REPL::Plugin::LexEnv)
56 plugins loaded (and there are many more available).
57 Although the shell might support "up-arrow" history, the History plugin adds
58 "bang" history to that so you can re-execute chosen commands (with e.g.
59 `!53`). The LexEnv plugin ensures that lexical variables declared with the
60 `my` keyword will automatically persist between statements executed in the
63 When you `use` any Perl module, the `import()` will work as expected - the
64 exported functions from that module are available for immediate use:
66 $_ carp "I'm dieeeing!\n"
67 String found where operator expected at (eval 129) line 5, near "carp "I'm dieeeing!\n""
68 (Do you need to predeclare carp?)
69 Compile error: syntax error at (eval 129) line 5, near "carp "I'm dieeeing!\n""
70 BEGIN not safe after errors--compilation aborted at (eval 129) line 5.
74 $_ carp "I'm dieeeing!\n"
76 at /usr/share/perl5/Lexical/Persistence.pm line 327
80 To quit from the shell, hit `Ctrl+D` or `Ctrl+C`.
82 MSWin32 NOTE: control keys won't work if TERM=dumb
83 because readline functionality will be disabled.
87 For particular projects you might well end up running the same commands each
88 time the REPL shell starts up - loading Perl modules, setting configuration,
89 and so on. A run control file lets you have this done automatically, and you
90 can have multiple files for different projects.
92 By default the `re.pl` program looks for `$HOME/.re.pl/repl.rc`, and
93 runs whatever code is in there as if you had entered it at the REPL shell
96 To set a new run control file that's also in that directory, pass it as a
99 system$ re.pl --rcfile myproject.pc
101 If the filename happens to contain a forward slash, then it's used absolutely,
102 or realive to the current working directory:
104 system$ re.pl --rcfile /path/to/my/project/repl.rc
106 Within the run control file you might want to load plugins. This is covered in
107 ["The REPL shell object"](#the-repl-shell-object) section, below.
111 To allow for the sharing of run control files, you can fashion them into a
112 Perl module for distribution (perhaps via the CPAN). For more information on
113 this feature, please see the [Devel::REPL::Profile](https://metacpan.org/pod/Devel::REPL::Profile) manual page.
115 A `Standard` profile ships with `Devel::REPL`; it loads the following plugins
116 (note that some of these require optional features -- or you can also use the
119 - [Devel::REPL::Plugin::History](https://metacpan.org/pod/Devel::REPL::Plugin::History)
120 - [Devel::REPL::Plugin::LexEnv](https://metacpan.org/pod/Devel::REPL::Plugin::LexEnv)
121 - [Devel::REPL::Plugin::DDS](https://metacpan.org/pod/Devel::REPL::Plugin::DDS)
122 - [Devel::REPL::Plugin::Packages](https://metacpan.org/pod/Devel::REPL::Plugin::Packages)
123 - [Devel::REPL::Plugin::Commands](https://metacpan.org/pod/Devel::REPL::Plugin::Commands)
124 - [Devel::REPL::Plugin::MultiLine::PPI](https://metacpan.org/pod/Devel::REPL::Plugin::MultiLine::PPI)
125 - [Devel::REPL::Plugin::Colors](https://metacpan.org/pod/Devel::REPL::Plugin::Colors)
126 - [Devel::REPL::Plugin::Completion](https://metacpan.org/pod/Devel::REPL::Plugin::Completion)
127 - [Devel::REPL::Plugin::CompletionDriver::INC](https://metacpan.org/pod/Devel::REPL::Plugin::CompletionDriver::INC)
128 - [Devel::REPL::Plugin::CompletionDriver::LexEnv](https://metacpan.org/pod/Devel::REPL::Plugin::CompletionDriver::LexEnv)
129 - [Devel::REPL::Plugin::CompletionDriver::Keywords](https://metacpan.org/pod/Devel::REPL::Plugin::CompletionDriver::Keywords)
130 - [Devel::REPL::Plugin::CompletionDriver::Methods](https://metacpan.org/pod/Devel::REPL::Plugin::CompletionDriver::Methods)
131 - [Devel::REPL::Plugin::ReadlineHistory](https://metacpan.org/pod/Devel::REPL::Plugin::ReadlineHistory)
135 Plugins are a way to add functionality to the REPL shell, and take advantage of
136 `Devel::REPL` being based on the [Moose](https://metacpan.org/pod/Moose) object system for Perl 5. This
137 means it's simple to 'hook into' many steps of the R-E-P-L process. Plugins
138 can change the way commands are interpreted, or the way their results are
139 output, or even add commands to the shell environment.
141 A number of plugins ship with `Devel::REPL`, and more are available on the
142 CPAN. Some of the shipped plugins are loaded in the default profile, mentioned
143 above. These plugins can be loaded in your ` $HOME/.re.pl/repl.rc ` like:
145 load_plugin qw( CompletionDriver::Global DumpHistory );
147 Writing your own plugins is not difficult, and is discussed in the
148 [Devel::REPL::Plugin](https://metacpan.org/pod/Devel::REPL::Plugin) manual page, along with links to the manual pages of
149 all the plugins shipped with `Devel::REPL`.
151 ## The REPL shell object
153 From time to time you'll want to interact with or manipulate the
154 `Devel::REPL` shell object itself; that is, the instance of the shell you're
157 The object is always available through the `$_REPL` variable. One common
158 requirement is to load an additional plugin, after your profile and run
159 control files have already been executed:
161 $_ $_REPL->load_plugin('Timing');
163 $_ print "Hello again, world!\n"
165 Took 0.00148296356201172 seconds.
171 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
172 additional plugins. You can install any of these features by installing this
173 distribution interactively (e.g. `cpanm --interactive Devel::REPL`).
175 - Completion plugin - extensible tab completion
176 - DDS plugin - better format results with Data::Dump::Streamer
177 - DDC plugin - even better format results with Data::Dumper::Concise
178 - INC completion driver - tab complete module names in use and require
179 - Interrupt plugin - traps SIGINT to kill long-running lines
180 - Keywords completion driver - tab complete Perl keywords and operators
181 - LexEnv plugin - variables declared with "my" persist between statements
182 - MultiLine::PPI plugin - continue reading lines until all blocks are closed
183 - Nopaste plugin - upload a session\\'s input and output to a Pastebin
184 - PPI plugin - PPI dumping of Perl code
185 - Refresh plugin - automatically reload libraries with Module::Refresh
189 Matt S Trout - mst (at) shadowcatsystems.co.uk ([http://www.shadowcatsystems.co.uk/](http://www.shadowcatsystems.co.uk/))
193 - Stevan Little - stevan (at) iinteractive.com
194 - Alexis Sukrieh - sukria+perl (at) sukria.net
196 - mgrimes - mgrimes (at) cpan dot org
197 - Shawn M Moore - sartak (at) gmail.com
198 - Oliver Gorwits - oliver on irc.perl.org
199 - Andrew Moore - `<amoore@cpan.org>`
200 - Norbert Buchmuller `<norbi@nix.hu>`
201 - Dave Houston `<dhouston@cpan.org>`
203 - Karen Etheridge `<ether@cpan.org>`
207 This library is free software under the same terms as perl itself