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.

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

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

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

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

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

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

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

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

  my $x = Df([ $tag, $tweak ] => @things);

  return Dwarn([ foo => sub { +{ @_ } } ], %things);

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 through 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/>.