/ 
Data-Dumper-Compact-0.003003
River stage two • 10 direct dependents • 13 total dependents
/ Devel::DDCWarn

NAME

Devel::DDCWarn - Easy printf-style debugging with Data::Dumper::Compact

SYNOPSIS

use Devel::DDCWarn;

my $x = Dwarn some_sub_call(); # warns and returns value
my @y = Derr other_sub_call(); # prints to STDERR and returns value

my $x = DwarnT X => some_sub_call(); # warns with tag 'X' and returns value
my @y = DerrT X => other_sub_call(); # similar

DESCRIPTION

Devel::DDCWarn is a Devel::Dwarn equivalent for Data::Dumper::Compact.

The idea, basically, is that it's incredibly annoying to start off with code like this:

return some_sub_call();

and then realise you need the value, so you have to write:

my @ret = some_sub_call();
warn Dumper [ THE_THING => @ret ];
return @ret;

With Devel::DDCWarn, one can instead write:

return DwarnT THE_THING => some_sub_call();

and expect it to Just Work.

To integrate with your logging, you can do:

our $L = sub { $log->debug("DDC debugging: ".$_[0] };
...
return DtoT $L, THE_THING => some_sub_call();

When applying printf debugging style approaches, it's also very useful to be able to do:

perl -MDevel::DDCwarn ...

and then within the code being debugged, abusing the fact that a prefix of :: is short for main:: so we can add:

return ::DwarnT THE_THING => some_sub_call();

and if we forget to remove them, the lack of command-line Devel::DDCWarn exported into main:: will produce a compile time failure. This is exceedingly useful for noticing you forgot to remove a debug statement before you commit it along with the test and fix.

EXPORTS

All of these subroutines are exported by default.

Data::Dumper::Compact is referred to herein as DDC.

Dwarn

my $x = Dwarn make_x();
my @y = Dwarn make_y_array();

warn()s the "Df" DDC dump of its input, then returns the first element in scalar context or all arguments in list context.

Derr

my $x = Derr make_x();
my @y = Derr make_y_array();

prints the "Df" DDC dump of its input to STDERR, then returns the first element in scalar context or all arguments in list context.

DwarnT

my $x = Dwarn TAG => make_x();
my @y = Dwarn TAG => make_y_array();

Like "Dwarn", but passes its first argument, the tag, through to "DfT" but skips it for the return value.

DerrT

my $x = Derr TAG => make_x();
my @y = Derr TAG => make_y_array();

Like "Derr", but accepts a tag argument that is included in the output but is skipped for the return value.

Dto

Dto(sub { warn $_[0] }, @args);

Like "Dwarn", but instead of warning, calls the subroutine passed as the first argument - this function is low level but still returns the @args.

DtoT

DtoT(sub { err $_[0] }, $tag, @args);

The tagged version of Dto.

Df

my $x = Df($thing);
my $y = Df(@other_things);

A single value is returned formatted by DDC. Multiple values are transformed to a DDC list.

DfT

my $x = Df($tag => $thing);
my $y = Df($tag => @other_things);

A tag plus a single value is formatted as a two element list. A tag plus multiple values is formatted as a list containing the tag and a list of the values.

CONFIGURATION

use Devel::DDCWarn \%options, ...;

perl -MDevel::DDCWarn=-optname,value,-other,value ...;

$Devel::DDCWarn::ddc = Data::Dumper::Compact->new(\%options);

Options passed as a hashref on a use line or using - prefixing on the command line are used to initialise the Data::Dumper::Compact object.

Note that this primarily being a debugging and/or scripting oriented tool, if something initialises us again later, this will reset the (single) global $ddc used by this code and change all output throught the process.

However, if you need a localised change of formatting style, $ddc is a full fledged global so you are absolutely allowed to local it:

my $ddc = Data::Dumper::Compact->new(\%my_local_options);
local $Devel::DDCWarn::ddc = $ddc;

If you have a convincing reason for using this functionality in a way where the globality is a bug rather than a feature, please start a conversation with the authors so we can figure out what to do about it.

COPYRIGHT

Copyright (c) 2019 the "AUTHOR" in Data::Dumper::Compact and "CONTRIBUTORS" in Data::Dumper::Compact as listed in Data::Dumper::Compact.

LICENSE

This library is free software and may be distributed under the same terms as perl itself. See https://dev.perl.org/licenses/.