AFAIK Win32::API::Prototype was created when Win32::API had no handy importing style

      use Win32::API;
      Win32::API->Import(
          'mydll', 'int sum_integers(int a, int b)',
      );  
      $return = sum_integers(3, 2);
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Yes I know that Win32::API uses eval for importing but it works, so the searching and installing Win32::API::Prototype is not necessary.

As for Win32::API::Prototype string manipulation functions, they are not seem very useful. I think Win32::API should take care about length of input strings and truncating of output ones. Unfortunately it's not implemented there. May be I'll do it if the author don't.