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יובל קוג'מן (Yuval Kogman) > Devel-PartialDump-0.12 > Devel::PartialDump



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Module Version: 0.12   Source   Latest Release: Devel-PartialDump-0.20


Devel::PartialDump - Partial dumping of data structures, optimized for argument printing.


        use Devel::PartialDump;

        sub foo {
                print "foo called with args: " . Devel::PartialDump->new->dump(@_);

        use Devel::PartialDump qw(warn);

        # warn is overloaded to create a concise dump instead of stringifying $some_bad_data
        warn "this made a boo boo: ", $some_bad_data


This module is a data dumper optimized for logging of arbitrary parameters.

It attempts to truncate overly verbose data, in a way that is hopefully more useful for diagnostics warnings than

        warn Dumper(@stuff);

Unlike other data dumping modules there are no attempts at correctness or cross referencing, this is only meant to provide a slightly deeper look into the data in question.

There is a default recursion limit, and a default truncation of long lists, and the dump is formatted on one line (new lines in strings are escaped), to aid in readability.

You can enable it temporarily by importing functions like warn, croak etc to get more informative errors during development, or even use it as:

        BEGIN { local $@; eval "use Devel::PartialDump qw(...)" }

to get DWIM formatting only if it's installed, without introducing a dependency.


"foo" => "bar"
    foo => "bar"
foo => "bar", gorch => [ 1, "bah" ]
    foo => "bar", gorch => [ 1, "bah" ]
[ { foo => ["bar"] } ]
    [ { foo => ARRAY(0x9b265d0) } ]
[ 1 .. 10 ]
    [ 1, 2, 3, 4, 5, 6, ... ]
"foo" . chr(1)



The maximum character length of the dump.

Anything bigger than this will be truncated.

Not defined by default.


The maximum number of elements (array elements or pairs in a hash) to print.

Defualts to 6.


The maximum level of recursion.

Defaults to 2.


Whether or not to let objects stringify themeslves, instead of using "StrVal" in overload to avoid sideffects.

Defaults to false (no overloading).


Whether or not to autodetect named args as pairs in the main dump function. If this attribute is true, and the top level value list is even sized, and every odd element is not a reference, then it will dumped as pairs instead of a list.


All exports are optional, nothing is exported by default.

This module uses Sub::Exporter, so exports can be renamed, curried, etc.


See the various methods for behavior documentation.

These methods will use $Devel::PartialDump::default_dumper as the invocant if the first argument is not blessed and isa Devel::PartialDump, so they can be used as functions too.

Particularly warn can be used as a drop in replacement for the built in warn:

        warn "blah blah: ", $some_data;

by importing

        use Devel::PartialDump qw(warn);

$some_data will be have some of it's data dumped.


The default dumper object to use for export style calls.

Can be assigned to to alter behavior globally.

This is generally useful when using the warn export as a drop in replacement for CORE::warn.


warn @blah

A warpper for dump that prints strings plainly.

show @blah
show_scalar $x

Like warn, but instead of returning the value from warn it returns its arguments, so it can be used in the middle of an expression.

Note that

        my $x = show foo();

will actually evaluaate foo in list context, so if you only want to dump a single element and retain scalar context use

        my $x = show_scalar foo();

which has a prototype of $ (as opposed to taking a list).

This is similar to the venerable Ingy's fabulous and amazing XXX module.


Drop in replacements for Carp exports, that format their arguments like warn.

dump @stuff

Returns a one line, human readable, concise dump of @stuff.

If called in void context, will warn with the dump.

Truncates the dump according to max_length if specified.

dump_as_list $depth, @stuff
dump_as_pairs $depth, @stuff

Dump @stuff using the various formatting functions.

Dump as pairs returns comma delimited pairs with => between the key and the value.

Dump as list returns a comma delimited dump of the values.

frmat $depth, $value
format_key $depth, $key
format_object $depth, $object
format_ref $depth, $Ref
format_array $depth, $array_ref
format_hash $depth, $hash_ref
format_undef $depth, undef
format_string $depth, $string
format_number $depth, $number
quote $string

The various formatting methods.

You can override these to provide a custom format.

format_array and format_hash recurse with $depth + 1 into dump_as_list and dump_as_pairs respectively.

format_ref delegates to format_array and format_hash and does the max_depth tracking. It will simply stringify the ref if the recursion limit has been reached.


This module is maintained using git. You can get the latest version from


Yuval Kogman <>


        Copyright (c) 2008 Yuval Kogman. All rights reserved
        This program is free software; you can redistribute
        it and/or modify it under the same terms as Perl itself.
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