Hook::LexWrap and core functions

[Alien]

Hello!
Could you guys show me an example of how to wrap a built-in function? push would be great , if it's not too much trouble. Thanks

[ikegami]

Overriding Built-in Functions

First make sure you can override it

>perl -wle"print( prototype( 'CORE::chomp' ) )"
Use of uninitialized value in print at -e line 1.   <- Can't


>perl -wle"print( prototype( 'CORE::push' ) )"
\@@                                                 <- Can

Then go ahead and do it:

BEGIN {
   *CORE::GLOBAL::push = sub(\@@) {
      my $array = shift(@_);
      print("Pushing\n");
      return CORE::push(@$array, @_);
   };
}

[Alien]

Thank you for your reply ! But,is it possible to wrap it using Hook::LexWrap ? I get a "Can't wrap non-existent subroutine CORE::push"

[ikegami]

Nope, and the error accurately describes the reason you can't. push is not a sub, so you can't get its address, so it can't be wrapped.

You might be able to wrap *CORE::GLOBAL::push once you create it.

[blazar]

Now that I think of it, prototypes are already somewhat deprecated, and of course we're "all" (well, I for one, and I bet most too, but I'm sure someone will disagree instead...) waiting for Perl 6 and its multi's with real signatures, OTOH it would be nice and IMHO not terribly sci-fi-like if prototypes allowed alternation (which I sort of consistently, I hope, represent hereafter with a pipe | character) so that e.g. chomp could have a prototype of:

@|_