On 9/12/06, JupiterHost.Net <[EMAIL PROTECTED]> wrote:
I'm trying to change the behavior of a function (whose use of and call I
have no control over) to avoid some nasty behavior in certain circumstances.
Its easy enough to redefine it but after the hairy part is done I want
to change it back.
Similar to how you can:
local $var;
What you need is just a "local *What::ever = \&new_sub;" I tried to
write similar to what you need. The code below overrides
File::Copy::copy so that it dumps the arguments before copying. This
is done inside a block:
#!/usr/bin/perl
use strict;
use warnings;
use File::Copy ();
my ($source, $target) = @ARGV;
{
my $copy = \&File::Copy::copy; # save it
#no warnings qw(redefine);
local *File::Copy::copy = sub {
warn "copy(@_)\n";
$copy->(@_);
};
File::Copy::copy($source, $target);
}
# File::Copy::copy is magically restored here
If you don't use the "no warnings" bit you will see a "Subroutine
File::Copy::copy redefined".
You don't need to save it like I did at "my $copy =
\&File::Copy::copy; # save it" if you don't need the old code. In the
example, I just added behavior and invoked the old code to do the hard
work.
What the statement does
local *What::ever = \&my_sub; # with a named sub
or
local *What::ever = sub { }; # with a closure
is to locally redefine the *What::ever{CODE} slot of the glob.
Regards,
Adriano.
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