Overlays: Difference between revisions

m clarify
Add an example for overriding Perl packages, since the other languages have examples of special cases. This also helps make a definitive version that can be updated (going forward) for people coming from search engines too, rather than forum posts...etc. from years ago.
 
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       };
       };
     };
     };
</syntaxhighlight>
=== Perl Package overlays ===
Perl packages require some extra care prevent the error <code>undefined variable 'perl'</code>. This example turns off tests for the <code>example</code> package:
<syntaxhighlight lang="nix">
  final: prev: {
    perlPackages = prev.perlPackages // {
      example = prev.perlPackages.example.overrideAttrs (attrs:
        { doChecks = false; }
      )
    };
  };
</syntaxhighlight>
</syntaxhighlight>