Hmm. Let me see if I understand: you want to be able
to do something like grep or map, where your code gets
passed a subref which you then call back?
If so, you don't need to worry about changing packages
at the time you call it, since it will have already
picked up the proper package when it was defined (and
compiled) in the caller's code:
package my;
$global = 'in_my';
sub own_map(&@) {
my $code = shift;
my @return = ();
push @return, $code->() for @_;
@return;
}
package main;
$global = 'in_main';
print my::own_map { $_, " ", $global, "\n" } (1..20);
# prints "1 in_main\n", "2 in_main\n" and so on
In the above code, my::own_map could have molested
${ (caller)[0] . "::global" } to pass a value
in to the block. I guess this might be OK (although it's
clearly an abuse of caller, which AFAIK was intended
for debugging), as long as it's well documented and you
are careful to localize everything.
Updated: removed a confusing and unneeded $_ argument
on the line that calls the callback. Oops!