hi,lists,
I have seen this thread on perlmonk,and it make me confused too.Can anyone here
explain that?Thanks.
Quote:
-------
Basically, deleting subroutines from a symbol table seems a bit buggy, but I
don't know if this behavior is documented or not.
#!/usr/bin/perl -l
sub this { 'this' }
print this;
undef &main::this; # undefine the code slot
print main->can('this') ? 'main->can("this")' : '! main->can("this")';
eval {print this};
print $@;
undef *main::this; # undefine the entire glob
print main->can('this') ? 'main->can("this")' : '! main->can("this")';
__END__
# result
this
main->can("this")
Undefined subroutine &main::this called at sub.pl line 7.
! main->can("this")
The first time I try to remove the subroutine via undef it still leaves a
CODE slot in the symbol table's *this glob. I can't just use delete because it's
not an array or a hash (it fails if you try). This is bad in procedural code but
it's awful in OO code because $object->can('this') will succeed even if the
method has been deleted.
This leaves me with having to undefine the entire glob but that's a
horrible solution because the other slots in the glob, if any, are blown away.
Is this a known/documented bug/feature in Perl? Is there a workaround?
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