usage of __PACKAGE_

eXile has asked for the wisdom of the Perl Monks concerning the following question:

Hi, here is a sample of my debug session:

  DB<11> x __PACKAGE__
0  'Item::Mimepart'
  DB<12> x $Cache::MaxSize{'Item::Mimepart'}
0  2000
  DB<13> x $Cache::MaxSize{__PACKAGE__}
0  undef
[download]

From 11 and 12 I thought $Cache::MaxSize{__PACKAGE__} = 2000 (at least that is what I want it to be), but it's undef. What am I missing?

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Re: usage of __PACKAGE__ by borisz (Canon) on Jul 20, 2004 at 16:45 UTC
what you need is tell perl that your key name is not __PACKAGE__. `$Cache::MaxSize{ +__PACKAGE__ } = 2000;` [download] or `$Cache::MaxSize{ '' . __PACKAGE__ } = 2000;` [download] Boris	[reply] [d/l] [select]
Re: usage of __PACKAGE__ by blokhead (Monsignor) on Jul 20, 2004 at 16:47 UTC
`$ perl -MO=Deparse -e '$hash{__PACKAGE__} = 1' $hash{'__PACKAGE__'} = 1;` [download] __PACKAGE__ gets treated as a string, as does any bareword (keyword or not) that you use to index a hash (think `$foo{shift}`). The easiest fix is adding a plus sign to make it an expression instead of a string. `$ perl -MO=Deparse -e '$hash{+__PACKAGE__} = 1' $hash{'main'} = 1;` [download] blokhead	[reply] [d/l] [select]