You get all sorts of warnings when you compile the A and B packages. Mismatching prototypes, ambiguous calls, etc.

subs.pm doesn't do anything but put something in the code slot in the glob. The prototype mismatch is because subs assigns a subroutine with no prototype to &write and then you redefine that. If you do the glob assignment first (in a BEGIN block) and have the subs statement after the glob assignment, then everything works. I was intrigued by why subs does the trick with its glob assignment, but simplly having

BEGIN { *write = \&A::write }   # Doesn't work!
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didn't. I've boiled it down to that the assignment has to be done by some other package (not necessarily subs, e.g. Exporter). So this works:

# Perl 5.8.8

{
  package X; # I change to X and Y because B is taken.
  sub write (&) { print $_[0]->() }
}
{
  package Y;
  BEGIN {
    package Something::Else;
    *Y::write = \&X::write;
  }

  write { 'OK' };
}

__END__
OK
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I have no idea why you have to switch package. I'd appreciate if someone could point me to any perldoc that explains this. I haven't found anything about it.

lodin