1Devel::REPL(3) User Contributed Perl Documentation Devel::REPL(3)
2
6 Devel::REPL - a modern perl interactive shell
7
9 my $repl = Devel::REPL->new;
10 $repl->load_plugin($_) for qw(History LexEnv);
11 $repl->run
12 Alternatively, use the 're.pl' script installed with the distribution
14 system$ re.pl
16
18 This is an interactive shell for Perl, commonly known as a REPL - Read,
19 Evaluate, Print, Loop. The shell provides for rapid development or
20 testing of code without the need to create a temporary source code
21 file.
22 Through a plugin system, many features are available on demand. You can
24 also tailor the environment through the use of profiles and run control
25 files, for example to pre-load certain Perl modules when working on a
26 particular project.
27
29 To start a shell, follow one of the examples in the "SYNOPSIS" above.
30 Once running, the shell accepts and will attempt to execute any code
32 given. If the code executes successfully you'll be shown the result,
33 otherwise an error message will be returned. Here are a few examples:
34 $_ print "Hello, world!\n"
36 Hello, world!
37 1
38 $_ nosuchfunction
39 Compile error: Bareword "nosuchfunction" not allowed while "strict subs" in use at (eval 130) line 5.
40 $_
42 In the first example above you see the output of the command ("Hello,
44 world!"), if any, and then the return value of the statement (1).
45 Following that example, an error is returned when the execution of some
46 code fails.
47 Note that the lack of semicolon on the end is not a mistake - the code
49 is run inside a Block structure (to protect the REPL in case the code
50 blows up), which means a single statement doesn't require the
51 semicolon. You can add one if you like, though.
52 If you followed the first example in the "SYNOPSIS" above, you'll have
54 the History and LexEnv plugins loaded (and there are many more
55 available). Although the shell might support "up-arrow" history, the
56 History plugin adds "bang" history to that so you can re-execute chosen
57 commands (with e.g. "!53"). The LexEnv plugin ensures that lexical
58 variables declared with the "my" keyword will automatically persist
59 between statements executed in the REPL shell.
60 When you "use" any Perl module, the "import()" will work as expected -
62 the exported functions from that module are available for immediate
63 use:
64 $_ carp "I'm dieeeing!\n"
66 String found where operator expected at (eval 129) line 5, near "carp "I'm dieeeing!\n""
67 (Do you need to predeclare carp?)
68 Compile error: syntax error at (eval 129) line 5, near "carp "I'm dieeeing!\n""
69 BEGIN not safe after errors--compilation aborted at (eval 129) line 5.
70 $_ use Carp
72 $_ carp "I'm dieeeing!\n"
74 I'm dieeeing!
75 at /usr/share/perl5/Lexical/Persistence.pm line 327
76 1
77 $_
78 To quit from the shell, hit "Ctrl+D" or "Ctrl+C".
80 MSWin32 NOTE: control keys won't work if TERM=dumb
82 because readline functionality will be disabled.
83 Run Control Files
85 For particular projects you might well end up running the same commands
86 each time the REPL shell starts up - loading Perl modules, setting
87 configuration, and so on. A run control file lets you have this done
88 automatically, and you can have multiple files for different projects.
89 By default the "re.pl" program looks for "$HOME/.re.pl/repl.rc", and
91 runs whatever code is in there as if you had entered it at the REPL
92 shell yourself.
93 To set a new run control file that's also in that directory, pass it as
95 a filename like so:
96 system$ re.pl --rcfile myproject.pc
98 If the filename happens to contain a forwardslash, then it's used
100 absolutely, or realive to the current working directory:
101 system$ re.pl --rcfile /path/to/my/project/repl.rc
103 Within the run control file you might want to load plugins. This is
105 covered in "The REPL shell object" section, below.
106 Profiles
108 To allow for the sharing of run control files, you can fashion them
109 into a Perl module for distribution (perhaps via the CPAN). For more
110 information on this feature, please see the Devel::REPL::Profile manual
111 page.
112 A default profile ships with "Devel::REPL"; it loads the following
114 plugins:
115 · Devel::REPL::Plugin::History
117 · Devel::REPL::Plugin::LexEnv
119 · Devel::REPL::Plugin::DDS
121 · Devel::REPL::Plugin::Packages
123 · Devel::REPL::Plugin::Commands
125 · Devel::REPL::Plugin::MultiLine::PPI
127 Plugins
129 Plugins are a way to add funcionality to the REPL shell, and take
130 advantage of "Devel::REPL" being based on the Moose object system for
131 Perl 5. This means it's simple to 'hook into' many steps of the R-E-P-L
132 process. Plugins can change the way commands are interpreted, or the
133 way their results are output, or even add commands to the shell
134 environment.
135 A number of plugins ship with "Devel::REPL", and more are available on
137 the CPAN. Some of the shipped plugins are loaded in the default
138 profile, mentioned above.
139 Writing your own plugins is not difficult, and is discussed in the
141 Devel::REPL::Plugin manual page, along with links to the manual pages
142 of all the plugins shipped with "Devel::REPL".
143 The REPL shell object
145 From time to time you'll want to interact with or manipulate the
146 "Devel::REPL" shell object itself; that is, the instance of the shell
147 you're currently running.
148 The object is always available through the $_REPL variable. One common
150 requirement is to load an additional plugin, after your profile and run
151 control files have already been executed:
152 $_ $_REPL->load_plugin('Timing');
154 1
155 $_ print "Hello again, world!\n"
156 Hello again, world!
157 Took 0.00148296356201172 seconds.
158 1
159 $_
160
162 In addition to the contents of the standard Perl distribution, you will
163 need the following:
164 · Moose >= 0.74
166 · MooseX::Object::Pluggable >= 0.0009
168 · MooseX::Getopt >= 0.18
170 · MooseX::AttributeHelpers >= 0.16
172 · namespace::clean
174 · File::HomeDir
176 · Task::Weaken
178 · B::Concise
180 · Term::ANSIColor
182 · Devel::Peek
184 Optionally, some plugins if installed will require the following
186 modules:
187 · PPI
189 · Data::Dump::Streamer
191 · Data::Dumper::Concise
193 · File::Next
195 · Sys::SigAction
197 · B::Keywords
199 · Lexical::Persistence
201 · App::Nopaste
203 · Module::Refresh
205
207 Matt S Trout - mst (at) shadowcatsystems.co.uk
208 (<http://www.shadowcatsystems.co.uk/>)
209
211 Stevan Little - stevan (at) iinteractive.com
212 Alexis Sukrieh - sukria+perl (at) sukria.net
213 epitaph
214 mgrimes - mgrimes (at) cpan dot org
215 Shawn M Moore - sartak (at) gmail.com
216 Oliver Gorwits - oliver on irc.perl.org
217 Andrew Moore - "<amoore@cpan.org>"
218 Norbert Buchmuller "<norbi@nix.hu>"
219 Dave Houston "<dhouston@cpan.org>"
220 Chris Marshall
221
223 This library is free software under the same terms as perl itself
224perl v5.12.1 2010-06-15 Devel::REPL(3)