Commit | Line | Data |
cf51843c |
1 | package Devel::REPL::Plugin::OutputCache; |
2 | |
3 | use Moose::Role; |
4 | use namespace::clean -except => [ 'meta' ]; |
5 | |
6 | has output_cache => ( |
7 | is => 'rw', |
8 | isa => 'ArrayRef', |
9 | default => sub { [] }, |
10 | lazy => 1, |
11 | ); |
12 | |
588f0734 |
13 | has warned_about_underscore => ( |
14 | is => 'rw', |
15 | isa => 'Bool', |
16 | default => 0, |
17 | lazy => 1, |
18 | ); |
19 | |
cf51843c |
20 | around 'eval' => sub { |
21 | my $orig = shift; |
22 | my ($self, $line) = @_; |
23 | |
588f0734 |
24 | my $has_underscore = *_{CODE}; |
25 | if ($has_underscore && !$self->warned_about_underscore) { |
26 | warn "OutputCache: Sub _ already defined."; |
27 | $self->warned_about_underscore(1); |
28 | } |
29 | else { |
30 | # if _ is removed, then we should warn about it again if it comes back |
31 | $self->warned_about_underscore(0); |
32 | } |
33 | |
34 | # this needs to be a postfix conditional for 'local' to work |
35 | local *_ = sub () { $self->output_cache->[-1] } unless $has_underscore; |
cf51843c |
36 | |
37 | my @ret; |
38 | if (wantarray) { |
39 | @ret = $self->$orig($line); |
40 | } |
41 | else { |
42 | $ret[0] = $self->$orig($line); |
43 | } |
44 | |
45 | push @{ $self->output_cache }, @ret > 1 ? \@ret : $ret[0]; |
46 | return wantarray ? @ret : $ret[0]; |
47 | }; |
48 | |
49 | 1; |
50 | |
51 | __END__ |
52 | |
53 | =head1 NAME |
54 | |
55 | Devel::REPL::Plugin::OutputCache - remember past results, _ is most recent |
56 | |
57 | =head1 SYNOPSIS |
58 | |
59 | > 21 / 7 |
60 | 3 |
61 | > _ * _ |
62 | 9 |
63 | > sub { die "later" } |
64 | sub { die "later" } |
65 | > _->() |
66 | Runtime error: later |
67 | |
68 | =head1 DESCRIPTION |
69 | |
70 | Re-using results is very useful when working in a REPL. With C<OutputCache> you |
71 | get C<_>, which holds the past result. The benefit is that you can build up |
72 | your result instead of having to type it in all at once, or store it in |
73 | intermediate variables. C<OutputCache> also provides |
74 | C<< $_REPL->output_cache >>, an array reference of all results in this session. |
75 | |
76 | Devel::REPL already has a similar plugin, L<Devel::REPL::Plugin::History>. |
77 | There are some key differences though: |
78 | |
79 | =over 4 |
80 | |
81 | =item Input vs Output |
82 | |
83 | C<History> remembers input. C<OutputCache> remembers output. |
84 | |
85 | =item Munging vs Pure Perl |
86 | |
87 | C<History> performs regular expressions on your input. C<OutputCache> provides |
88 | the C<_> sub as a hook to get the most recent result, and |
89 | C<< $_REPL->output_cache >> for any other results. |
90 | |
91 | =item Principle of Least Surprise |
92 | |
93 | C<History> will replace exclamation points in any part of the input. This is |
94 | problematic if you accidentally include one in a string, or in a C<not> |
95 | expression. C<OutputCache> uses a regular (if oddly named) subroutine so Perl |
96 | does the parsing -- no surprises. |
97 | |
98 | =back |
99 | |
100 | =head1 CAVEATS |
101 | |
102 | The C<_> sub is shared across all packages. This means that if a module is |
103 | using the C<_> sub, then there is a conflict and you should not use this |
104 | plugin. For example, L<Jifty> uses the C<_> sub for localization. Jifty is the |
105 | only known user. |
106 | |
107 | =head1 SEE ALSO |
108 | |
109 | C<Devel::REPL>, C<Devel::REPL::Plugin::History> |
110 | |
111 | =head1 AUTHOR |
112 | |
113 | Shawn M Moore, C<< <sartak at gmail dot com> >> |
114 | |
115 | =head1 COPYRIGHT AND LICENSE |
116 | |
117 | Copyright (C) 2007 by Shawn M Moore |
118 | |
119 | This library is free software; you can redistribute it and/or modify |
120 | it under the same terms as Perl itself. |
121 | |
122 | =cut |