2 Devel::REPL - a modern perl interactive shell
5 my $repl = Devel::REPL->new;
6 $repl->load_plugin($_) for qw(History LexEnv);
9 Alternatively, use the 're.pl' script installed with the distribution
14 This is an interactive shell for Perl, commonly known as a REPL - Read,
15 Evaluate, Print, Loop. The shell provides for rapid development or
16 testing of code without the need to create a temporary source code file.
18 Through a plugin system, many features are available on demand. You can
19 also tailor the environment through the use of profiles and run control
20 files, for example to pre-load certain Perl modules when working on a
24 To start a shell, follow one of the examples in the "SYNOPSIS" above.
26 Once running, the shell accepts and will attempt to execute any code
27 given. If the code executes successfully you'll be shown the result,
28 otherwise an error message will be returned. Here are a few examples:
30 $_ print "Hello, world!\n"
34 Compile error: Bareword "nosuchfunction" not allowed while "strict subs" in use at (eval 130) line 5.
38 In the first example above you see the output of the command ("Hello,
39 world!"), if any, and then the return value of the statement (1).
40 Following that example, an error is returned when the execution of some
43 Note that the lack of semicolon on the end is not a mistake - the code
44 is run inside a Block structure (to protect the REPL in case the code
45 blows up), which means a single statement doesn't require the semicolon.
46 You can add one if you like, though.
48 If you followed the first example in the "SYNOPSIS" above, you'll have
49 the History and LexEnv plugins loaded (and there are many more
50 available). Although the shell might support "up-arrow" history, the
51 History plugin adds "bang" history to that so you can re-execute chosen
52 commands (with e.g. "!53"). The LexEnv plugin ensures that lexical
53 variables declared with the "my" keyword will automatically persist
54 between statements executed in the REPL shell.
56 When you "use" any Perl module, the "import()" will work as expected -
57 the exported functions from that module are available for immediate use:
59 $_ carp "I'm dieeeing!\n"
60 String found where operator expected at (eval 129) line 5, near "carp "I'm dieeeing!\n""
61 (Do you need to predeclare carp?)
62 Compile error: syntax error at (eval 129) line 5, near "carp "I'm dieeeing!\n""
63 BEGIN not safe after errors--compilation aborted at (eval 129) line 5.
67 $_ carp "I'm dieeeing!\n"
69 at /usr/share/perl5/Lexical/Persistence.pm line 327
73 To quit from the shell, hit "Ctrl+D" or "Ctrl+C".
75 MSWin32 NOTE: control keys won't work if TERM=dumb
76 because readline functionality will be
80 For particular projects you might well end up running the same commands
81 each time the REPL shell starts up - loading Perl modules, setting
82 configuration, and so on. A run control file lets you have this done
83 automatically, and you can have multiple files for different projects.
85 By default the "re.pl" program looks for "$HOME/.re.pl/repl.rc", and
86 runs whatever code is in there as if you had entered it at the REPL
89 To set a new run control file that's also in that directory, pass it as
92 system$ re.pl --rcfile myproject.pc
94 If the filename happens to contain a forwardslash, then it's used
95 absolutely, or relative to the current working directory:
97 system$ re.pl --rcfile /path/to/my/project/repl.rc
99 Within the run control file you might want to load plugins. This is
100 covered in "The REPL shell object" section, below.
103 To allow for the sharing of run control files, you can fashion them into
104 a Perl module for distribution (perhaps via the CPAN). For more
105 information on this feature, please see the Devel::REPL::Profile manual
108 A default profile ships with "Devel::REPL"; it loads the following
111 * Devel::REPL::Plugin::History
113 * Devel::REPL::Plugin::LexEnv
115 * Devel::REPL::Plugin::DDS
117 * Devel::REPL::Plugin::Packages
119 * Devel::REPL::Plugin::Commands
121 * Devel::REPL::Plugin::MultiLine::PPI
124 Plugins are a way to add funcionality to the REPL shell, and take
125 advantage of "Devel::REPL" being based on the Moose object system for
126 Perl 5. This means it's simple to 'hook into' many steps of the R-E-P-L
127 process. Plugins can change the way commands are interpreted, or the way
128 their results are output, or even add commands to the shell environment.
130 A number of plugins ship with "Devel::REPL", and more are available on
131 the CPAN. Some of the shipped plugins are loaded in the default profile,
134 Writing your own plugins is not difficult once you understand all about
135 Moose and Moose Roles. A Devel::REPL::Plugin manual page is planned but
138 The REPL shell object
139 From time to time you'll want to interact with or manipulate the
140 "Devel::REPL" shell object itself; that is, the instance of the shell
141 you're currently running.
143 The object is always available through the $_REPL variable. One common
144 requirement is to load an additional plugin, after your profile and run
145 control files have already been executed:
147 $_ $_REPL->load_plugin('Timing');
149 $_ print "Hello again, world!\n"
151 Took 0.00148296356201172 seconds.
156 In addition to the contents of the standard Perl distribution, you will
161 * MooseX::Object::Pluggable >= 0.0009
163 * MooseX::Getopt >= 0.15
165 * MooseX::AttributeHelpers >= 0.14
173 Optionally, some plugins if installed will require the following
178 * Data::Dump::Streamer
184 * Lexical::Persistence
191 Matt S Trout - mst (at) shadowcatsystems.co.uk
192 (<http://www.shadowcatsystems.co.uk/>)
195 Stevan Little - stevan (at) iinteractive.com
196 Alexis Sukrieh - sukria+perl (at) sukria.net
198 mgrimes - mgrimes (at) cpan (dot) org
199 Shawn M Moore - sartak (at) gmail.com
200 Oliver Gorwits - oliver on irc.perl.org
204 This library is free software under the same terms as perl itself