How to redefine subroutines with Attribute::Handlers that run at BEGIN time?

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

I basically want to put a wrapper around a function when it's declared with a particular attribute. This would normally be easy, because when the handler is run, you get a reference to the symbol, so you can do this:

   sub myhandler : ATTR(CODE) {
      my($pkg, $symbol, $referent....) = @_;
      ...
      *{$symbol} = sub {
          # additional code
          goto &$referent;
       }
   }
[download]

However, the script(s) that uses the attribute is called from do(). That means that the CHECK and INIT blocks are not run. I tried changing the handler to be invoked at BEGIN time, but the problem there is that the $symbol is a string that says "ANON". So I have no where I can assign the newly generate sub.

Does anybody know a way to workaround this?

Comment on How to redefine subroutines with Attribute::Handlers that run at BEGIN time? Select or Download Code

Replies are listed 'Best First'.
Re: How to redefine subroutines with Attribute::Handlers that run at BEGIN time? by tilly (Archbishop) on Oct 05, 2003 at 17:52 UTC
I would suggest reporting your difficulty to p5p and hope that your feedback will help improve the implementation of attributes to make your problem go away. In the meantime my preferred solution would be to refactor your code so that the code which needs to be wrapped is not called from do. If that won't work, then the best that I can think of is to provide a function which does the wraps, and make sure that the scripts which need it call that at the top of the script, at runtime.	[reply]
Re: How to redefine subroutines with Attribute::Handlers that run at BEGIN time? by Juerd (Abbot) on Oct 15, 2003 at 06:52 UTC
So I have no where I can assign the newly generate sub. Maybe with Data::Swap, you can work around this problem. I haven't tried yet, but I'm thinking of something like `use Data::Swap; sub myhandler : ATTR(CODE) { my ($p, $s, $r, ...) = @_; swap $r, \my $o; swap $r, sub { # code &$o; }; }` [download] I have no idea if this would work. Juerd # { site => 'juerd.nl', plp_site => 'plp.juerd.nl', do_not_use => 'spamtrap' }	[reply] [d/l]