$Data::Dmp::OPT_PERL_VERSION

String, default: 5.010.

Set target Perl version. If you set this to, say 5.010, then the dumped code will keep compatibility with Perl 5.10.0. This is used in the following ways:

• passed to Regexp::Stringify
• when dumping code references

  For example, in perls earlier than 5.016, feature.pm does not understand:

   no feature ':all';
      

  so we replace it with:

   no feature;
      

$Data::Dmp::OPT_REMOVE_PRAGMAS

Bool, default: 0.

If set to 1, then pragmas at the start of coderef dump will be removed. Coderef dump is produced by B::Deparse and is of the form like:

 sub { use feature 'current_sub', 'evalbytes', 'fc', 'say', 'state', 'switch', 'unicode_strings', 'unicode_eval'; $a <=> $b }

If you want to dump short coderefs, the pragmas might be distracting. You can turn turn on this option which will make the above dump become:

 sub { $a <=> $b }

Note that without the pragmas, the dump might be incorrect.

$Data::Dmp::OPT_DEPARSE

Bool, default: 1.

Can be set to 0 to skip deparsing code. Coderefs will be dumped as "sub{"DUMMY"}" instead, like in Data::Dump.

$Data::Dmp::OPT_STRINGIFY_NUMBERS

Bool, default: 0.

If set to true, will dump numbers as quoted string, e.g. 123 as "123" instead of 123. This might be helpful if you want to compute the hash of or get a canonical representation of data structure.

$Data::Dmp::OPT_MAX_DUMP_LEN_BEFORE_ELLIPSIS

Int, default: 70.

Used by "dd_ellipsis" and "dmp_ellipsis".

dd

Usage:

 dd($data, ...); # returns $data

Exported by default. Like "Data::Dump"'s "dd" (a.k.a. "dump"), print one or more data to STDOUT. Unlike "Data::Dump"'s "dd", it always prints and return the original data (like XXX), making it convenient to insert into expressions. This also removes ambiguity and saves one "wantarray()" call.

dmp

Usage:

 my $dump = dmp($data, ...);

Exported by default. Return dump result as string. Unlike "Data::Dump"'s "dd" (a.k.a. "dump"), it never prints and only return the dump result.

dd_ellipsis

Usage:

 dd_ellipsis($data, ...); # returns data

Just like "dd", except will truncate its output to "$Data::Dmp::OPT_MAX_DUMP_LEN_BEFORE_ELLIPSIS" characters if dump is too long. Note that truncated dump will probably not be valid Perl code.

dmp_ellipsis

Usage:

 my $dump = dd_ellipsis($data, ...); # returns data

Just like "dmp", except will truncate dump result to "$Data::Dmp::OPT_MAX_DUMP_LEN_BEFORE_ELLIPSIS" characters if dump is too long. Note that truncated dump will probably not be valid Perl code.

When to use Data::Dmp? How does it compare to other dumper modules?

Data::Dmp might be suitable for you if you want a relatively fast pure-Perl data structure dumper to eval-able Perl code. It produces compact, single-line Perl code but offers little/no formatting options. Data::Dmp and Data::Dump module family usually produce Perl code that is "more eval-able", e.g. it can recreate circular structure.

Data::Dump produces visually nicer output (some alignment, use of range operator to shorten lists, use of base64 for binary data, etc) but no built-in option to produce compact/single-line output. It's more suitable for debugging. It's also relatively slow. I usually use its variant, Data::Dump::Color, for console debugging.

Data::Dumper is a core module, offers a lot of formatting options (like disabling hash key sorting, setting verboseness/indent level, and so on) but you usually have to configure it quite a bit before it does exactly like you want (that's why there are modules on CPAN that are just wrapping Data::Dumper with some configuration, like Data::Dumper::Concise et al). It does not support dumping Perl code that can recreate circular structures.

Of course, dumping to eval-able Perl code is slow (not to mention the cost of re-loading the code back to in-memory data, via eval-ing) compared to dumping to JSON, YAML, Sereal, or other format. So you need to decide first whether this is the appropriate route you want to take. (But note that there is also Data::Dumper::Limited and Data::Undump which uses a format similar to Data::Dumper but lets you load the serialized data without eval-ing them, thus achieving the speed comparable to JSON::XS).

Is the output guaranteed to be single line dump?

No. Some things can still produce multiline dump, e.g. newline in regular expression.