use Perl

• Bogus argument (Score:1)

  by Corion (7288) <corionNO@SPAMcpan.org> on 2007.07.31 11:41 (#56632) Homepage Journal

  Yes, C should be using A but I've read a lot of commercial code that just assumes other modules are loaded and its a horrible thing to debug.

  What a bogus argument. I would accept this if you had said "I have written a lot of commercial code that just assumes ...", but arguing a (unremovable, by now) misfeature of your code as something actually beneficial is quite a stretch. I hadn't looked at the source code of base.pm before people argued against it, but for my taste it is far too close to the code of UNIVERSAL::require which also silently gobbles up errors happening during requireing a file. The custom $SIG{__DIE__} handler also is an unneccessary complication that stems from the same idea that errors should not be visible upwards.

  Now, neither of these two points are what constitutes a "bug", but for some code that should basically be (less the error checking for recursive inheritance)

  package base;
  use strict;
  
  sub import {
      my ($class,$base) = @_;
      my $target = caller();
      (my $file = $base) =~ s!::|'!/!g;
      $file .= ".pm";
      require $file;
      {
          no strict 'refs';
          push @{ "$target\::ISA" }, $base;
      };
  };
  
  1

  base.pm has far too many lines and does far too many contortions that I do not want to track down just in case I have a weirdo error that base.pm chooses to suppress. Also, no bad action-at-a-distance occurs by messing with $VERSION and all errors point directly to the source like Can't locate Foo.pm in @INC (... instead of Base class package "Foo" is empty. - in 95% of the cases, that's exactly what's wanted, because somebody misspelled Foo.

  (Yes, I'm aware that my code forces every base class to be in a file with a name that matches that base class. If you don't want that, write your own @INC hook or fiddle with %INC.)

  Anyway - I started out liking base.pm, but after looking at the source code and having been bitten by UNIVERSAL::require gobbling my (syntax) errors far too many times, I don't want to become one of the people with anecdotal evidence that base.pm has bugs.

  Reply to This

  • Re: (Score:2)

    by schwern (1528)

    I think we're having a violent agreement. My example about the commercial code was illustrating the importance of inheriting at compile time vs setting @ISA at run time. All the other details of "use base" are orthogonal.
    
    Some people remember to put a BEGIN around setting @ISA (and @EXPORT) but most don't either because they forget or aren't aware.