1Data::Dmp(3) User Contributed Perl Documentation Data::Dmp(3)
2
6 Data::Dmp - Dump Perl data structures as Perl code
7
9 This document describes version 0.23 of Data::Dmp (from Perl
10 distribution Data-Dmp), released on 2017-01-30.
11
13 use Data::Dmp; # exports dd() and dmp()
14 dd [1, 2, 3]; # prints "[1,2,3]"
15 $a = dmp({a => 1}); # -> "{a=>1}"
16
18 Data::Dmp is a Perl dumper like Data::Dumper. It's compact (only about
19 175 lines of code long), starts fast and does not use any non-core
20 modules except Regexp::Stringify when dumping regexes. It produces
21 compact single-line output (similar to Data::Dumper::Concise). It
22 roughly has the same speed as Data::Dumper (usually a bit faster for
23 smaller structures) and faster than Data::Dump, but does not offer the
24 various formatting options. It supports dumping objects, regexes,
25 circular structures, coderefs. Its code is first based on Data::Dump: I
26 removed all the parts that I don't need, particularly the pretty
27 formatting stuffs) and added some features that I need like proper
28 regex dumping and coderef deparsing.
29
31 $Data::Dmp::OPT_PERL_VERSION => str (default: 5.010)
32 Set target Perl version. If you set this to, say 5.010, then the dumped
33 code will keep compatibility with Perl 5.10.0. This is used in the
34 following ways:
35 · passed to Regexp::Stringify
37 · when dumping code references
39 For example, in perls earlier than 5.016, feature.pm does not
41 understand:
42 no feature ':all';
44 so we replace it with:
46 no feature;
48 $Data::Dmp::OPT_REMOVE_PRAGMAS => bool (default: 0)
50 If set to 1, then pragmas at the start of coderef dump will be removed.
51 Coderef dump is produced by B::Deparse and is of the form like:
52 sub { use feature 'current_sub', 'evalbytes', 'fc', 'say', 'state', 'switch', 'unicode_strings', 'unicode_eval'; $a <=> $b }
54 If you want to dump short coderefs, the pragmas might be distracting.
56 You can turn turn on this option which will make the above dump become:
57 sub { $a <=> $b }
59 Note that without the pragmas, the dump might be incorrect.
61 $Data::Dmp::OPT_DEPARSE => bool (default: 1)
63 Can be set to 0 to skip deparsing code. Coderefs will be dumped as
64 "sub{"DUMMY"}" instead, like in Data::Dump.
65 $Data::Dmp::OPT_STRINGIFY_NUMBERS => bool (default: 0)
67 If set to true, will dump numbers as quoted string, e.g. 123 as "123"
68 instead of 123. This might be helpful if you want to compute the hash
69 of or get a canonical representation of data structure.
70
72 [1..10]:
73 Rate Data::Dump Data::Dumper Data::Dmp
74 Data::Dump 30417+-55/s -- -66.2% -74.0%
75 Data::Dumper 89888+-79/s 195.52+-0.6% -- -23.1%
76 Data::Dmp 116890+-160/s 284.29+-0.87% 30.04+-0.21% --
77 [1..100]:
79 Rate Data::Dump Data::Dmp Data::Dumper
80 Data::Dump 3712.3+-7.9/s -- -73.9% -74.9%
81 Data::Dmp 14211.3+-4.9/s 282.82+-0.82% -- -3.8%
82 Data::Dumper 14771+-28/s 297.9+-1.1% 3.94+-0.2% --
83 Some mixed structure:
85 Rate Data::Dump Data::Dmp Data::Dumper
86 Data::Dump 8764+-16/s -- -67.6% -80.1%
87 Data::Dmp 27016+-36/s 208.28+-0.7% -- -38.6%
88 Data::Dumper 43995+-13/s 402.02+-0.95% 62.85+-0.22% --
89
91 dd($data, ...) => $data ...
92 Exported by default. Like "Data::Dump"'s "dd" (a.k.a. "dump"), print
93 one or more data to STDOUT. Unlike "Data::Dump"'s "dd", it always
94 prints and return the original data (like XXX), making it convenient to
95 insert into expressions. This also removes ambiguity and saves one
96 "wantarray()" call.
97 dmp($data, ...) => $str
99 Exported by default. Return dump result as string. Unlike
100 "Data::Dump"'s "dd" (a.k.a. "dump"), it never prints and only return
101 the data.
102
104 When to use Data::Dmp? How does it compare to other dumper modules?
105 Data::Dmp might be suitable for you if you want a relatively fast pure-
106 Perl data structure dumper to eval-able Perl code. It produces compact,
107 single-line Perl code but offers little/no formatting options.
108 Data::Dmp and Data::Dump module family usually produce Perl code that
109 is "more eval-able", e.g. it can recreate circular structure.
110 Data::Dump produces visually nicer output (some alignment, use of range
112 operator to shorten lists, use of base64 for binary data, etc) but no
113 built-in option to produce compact/single-line output. It's more
114 suitable for debugging. It's also relatively slow. I usually use its
115 variant, Data::Dump::Color, for console debugging.
116 Data::Dumper is a core module, offers a lot of formatting options (like
118 disabling hash key sorting, setting verboseness/indent level, and so
119 on) but you usually have to configure it quite a bit before it does
120 exactly like you want (that's why there are modules on CPAN that are
121 just wrapping Data::Dumper with some configuration, like
122 Data::Dumper::Concise et al). It does not support dumping Perl code
123 that can recreate circular structures.
124 Of course, dumping to eval-able Perl code is slow (not to mention the
126 cost of re-loading the code back to in-memory data, via eval-ing)
127 compared to dumping to JSON, YAML, Sereal, or other format. So you need
128 to decide first whether this is the appropriate route you want to take.
129 (But note that there is also Data::Dumper::Limited and Data::Undump
130 which uses a format similar to Data::Dumper but lets you load the
131 serialized data without eval-ing them, thus achieving the speed
132 comparable to JSON::XS).
133 Is the output guaranteed to be single line dump?
135 No. Some things can still produce multiline dump, e.g. newline in
136 regular expression.
137
139 Please visit the project's homepage at
140 <https://metacpan.org/release/Data-Dmp>.
141
143 Source repository is at <https://github.com/perlancar/perl-Data-Dmp>.
144
146 Please report any bugs or feature requests on the bugtracker website
147 <https://rt.cpan.org/Public/Dist/Display.html?Name=Data-Dmp>
148 When submitting a bug or request, please include a test-file or a patch
150 to an existing test-file that illustrates the bug or desired feature.
151
153 Data::Dump and other variations/derivate works in Data::Dump::*.
154 Data::Dumper and its variants.
156 Data::Printer.
158 YAML, JSON, Storable, Sereal, and other serialization formats.
160
162 perlancar <perlancar@cpan.org>
163
165 This software is copyright (c) 2017 by perlancar@cpan.org.
166 This is free software; you can redistribute it and/or modify it under
168 the same terms as the Perl 5 programming language system itself.
169perl v5.30.0 2019-07-26 Data::Dmp(3)