Discipulus, here's an example using the autoload function from the Module::Load distribution. The autoload will bring in all available functions from the loaded module, where the load function only literally "requires" it (ie. doesn't bring in any functions):

package MyModule;
use strict;
use warnings;

use Module::Load;

my $dd_loaded;

BEGIN {
    $dd_loaded = eval { autoload Data::Dump; 1; };
    use if ! $dd_loaded, 'Data::Dumper';
}

_mydump(\%INC);

sub _mydump{
    my ($ref) = @_;

    if ($dd_loaded){
        print "using Data::Dump dd\n";
        dd $ref;
    }
    else {
        print "using Data::Dumper\n";
        print Dumper $ref;
    }
}

[download]

I have Data::Dump installed, so here's my output:

using Data::Dump dd
{
  "bytes.pm"             => "/home/spek/perl5/perlbrew/perls/perl-5.26
+.1/lib/5.26.1/bytes.pm",
  "Carp.pm"              => "/home/spek/perl5/perlbrew/perls/perl-5.26
+.1/lib/5.26.1/Carp.pm",
  "constant.pm"          => "/home/spek/perl5/perlbrew/perls/perl-5.26
+.1/lib/5.26.1/constant.pm",
  "Data/Dump.pm"         => "/home/spek/perl5/perlbrew/perls/perl-5.26
+.1/lib/site_perl/5.26.1/Data/Dump.pm",
  "Data/Dumper.pm"       => "/home/spek/perl5/perlbrew/perls/perl-5.26
+.1/lib/5.26.1/x86_64-linux/Data/Dumper.pm",
  "Exporter.pm"          => "/home/spek/perl5/perlbrew/perls/perl-5.26
+.1/lib/5.26.1/Exporter.pm",
  "File/Spec.pm"         => "/home/spek/perl5/perlbrew/perls/perl-5.26
+.1/lib/5.26.1/x86_64-linux/File/Spec.pm",
  "File/Spec/Unix.pm"    => "/home/spek/perl5/perlbrew/perls/perl-5.26
+.1/lib/5.26.1/x86_64-linux/File/Spec/Unix.pm",
  "if.pm"                => "/home/spek/perl5/perlbrew/perls/perl-5.26
+.1/lib/5.26.1/if.pm",
  "Module/Load.pm"       => "/home/spek/perl5/perlbrew/perls/perl-5.26
+.1/lib/5.26.1/Module/Load.pm",
  "overload.pm"          => "/home/spek/perl5/perlbrew/perls/perl-5.26
+.1/lib/5.26.1/overload.pm",
  "overloading.pm"       => "/home/spek/perl5/perlbrew/perls/perl-5.26
+.1/lib/5.26.1/overloading.pm",
  "strict.pm"            => "/home/spek/perl5/perlbrew/perls/perl-5.26
+.1/lib/5.26.1/strict.pm",
  "subs.pm"              => "/home/spek/perl5/perlbrew/perls/perl-5.26
+.1/lib/5.26.1/subs.pm",
  "vars.pm"              => "/home/spek/perl5/perlbrew/perls/perl-5.26
+.1/lib/5.26.1/vars.pm",
  "warnings.pm"          => "/home/spek/perl5/perlbrew/perls/perl-5.26
+.1/lib/5.26.1/warnings.pm",
  "warnings/register.pm" => "/home/spek/perl5/perlbrew/perls/perl-5.26
+.1/lib/5.26.1/warnings/register.pm",
  "XSLoader.pm"          => "/home/spek/perl5/perlbrew/perls/perl-5.26
+.1/lib/5.26.1/XSLoader.pm",
}

[download]

Now, if I change the following line in that script:

    $dd_loaded = eval { autoload Data::Dump; 1; };

[download]

To this (note the "x" at the end of Data::Dump):

    $dd_loaded = eval { autoload Data::Dumpx; 1; };
                                         # ^ <-- here

[download]

...the output changes, and it falls back on Data::Dumper:

using Data::Dumper
$VAR1 = {
          'Carp.pm' => '/home/spek/perl5/perlbrew/perls/perl-5.26.1/li
+b/5.26.1/Carp.pm',
          'constant.pm' => '/home/spek/perl5/perlbrew/perls/perl-5.26.
+1/lib/5.26.1/constant.pm',
          'Exporter.pm' => '/home/spek/perl5/perlbrew/perls/perl-5.26.
+1/lib/5.26.1/Exporter.pm',
          'warnings/register.pm' => '/home/spek/perl5/perlbrew/perls/p
+erl-5.26.1/lib/5.26.1/warnings/register.pm',
          'Module/Load.pm' => '/home/spek/perl5/perlbrew/perls/perl-5.
+26.1/lib/5.26.1/Module/Load.pm',
          'XSLoader.pm' => '/home/spek/perl5/perlbrew/perls/perl-5.26.
+1/lib/5.26.1/XSLoader.pm',
          'vars.pm' => '/home/spek/perl5/perlbrew/perls/perl-5.26.1/li
+b/5.26.1/vars.pm',
          'File/Spec.pm' => '/home/spek/perl5/perlbrew/perls/perl-5.26
+.1/lib/5.26.1/x86_64-linux/File/Spec.pm',
          'Data/Dumper.pm' => '/home/spek/perl5/perlbrew/perls/perl-5.
+26.1/lib/5.26.1/x86_64-linux/Data/Dumper.pm',
          'strict.pm' => '/home/spek/perl5/perlbrew/perls/perl-5.26.1/
+lib/5.26.1/strict.pm',
          'if.pm' => '/home/spek/perl5/perlbrew/perls/perl-5.26.1/lib/
+5.26.1/if.pm',
          'bytes.pm' => '/home/spek/perl5/perlbrew/perls/perl-5.26.1/l
+ib/5.26.1/bytes.pm',
          'warnings.pm' => '/home/spek/perl5/perlbrew/perls/perl-5.26.
+1/lib/5.26.1/warnings.pm',
          'File/Spec/Unix.pm' => '/home/spek/perl5/perlbrew/perls/perl
+-5.26.1/lib/5.26.1/x86_64-linux/File/Spec/Unix.pm'
        };

[download]

I use a BEGIN block in this case, as well as a global variable to hold the status of the Data::Dump load, but this is after all, just an example.

In reply to Re: load a module or another: Dumper or dd by stevieb
in thread load a module or another: Dumper or dd by Discipulus

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