Perl 5 version 10.1 documentation



  1. use Config::Extensions '%Extensions';
  2. if ($Extensions{PerlIO::via}) {
  3. # This perl has PerlIO::via built
  4. }


The Config::Extensions module provides a hash %Extensions containing all the core extensions that were enabled for this perl. The hash is keyed by extension name, with each entry having one of 3 possible values:

  • dynamic

    The extension is dynamically linked

  • nonxs

    The extension is pure perl, so doesn't need linking to the perl executable

  • static

    The extension is statically linked to the perl binary

As all values evaluate to true, a simple if test is good enough to determine whether an extension is present.

All the data uses to generate the %Extensions hash is already present in the Config module, but not in such a convenient format to quickly reference.


Nicholas Clark <>


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