Greetings;
This isn't technically an ActivePerl question, but I'm hoping someone
here can point me to some more information.
I'm puzzled about methods for passing hashes (or arrays) by reference to
a subroutine and updating the actual data in the hashes.
I know I can make a subroutine like this:
sub add2hash3 {
# refer to data indirectly but return reference to new hash
my %th = %{ shift @_ };
$th{'praying'} = 'mantis';
return \%th;
}
and call it like this:
%hash = %{ &add2hash3(\%hash) };
But that strikes me as kind of kludgy, and it can also be awkward if you
want to go in later and add additional input/return values to the
subroutine.
Another alternative that works is to write a function like:
sub add2hash {
# refer to data directly using hash reference
my $thRef = shift @_;
$thRef->{'worker'} = 'ant';
}
and call this like so:
&add2hash(\%hash);
All very well and good. But for some reason, the first thing I tried
didn't work. That was to write a function like this:
sub add2hash2 {
# refer to data indirectly using local (my) hash
my $thRef = shift @_;
my %th = %$thRef;
$th{'bee'} = 'hive';
}
It seems to me like this should be doing the same thing as add2hash
above, just defining a local hash name for convenience. But it doesn't
work the same and I'm not sure why. Is this explained anywhere in the
perl docs?
Thanks,
--Art
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