Hash reference

koknat has asked for the wisdom of the Perl Monks concerning the following question:

Problem: I have a hash %a that is arranged like this: $a{$b}{$c}{$d} = value

I want to call a function, passing in a reference to a part of the array

$w = "xyz";
&myfunc($a_ref->$w);
[download]

I thought this would work, but I get the error
Can't call method "xyz" on unblessed reference

# My workaround
my %a = %$a_ref;       
my %b = %{$a{$w}};
my $b_ref = \%b;    
&myfunc($b_ref);
[download]

The workaround does exactly what I want, but it's ugly and eats up memory and CPU cycles. Is there a better way?

Thanks

Comment on Hash reference Select or Download Code

Replies are listed 'Best First'.
Re: Hash reference by Transient (Hermit) on Jun 03, 2005 at 22:19 UTC
is xyz your key? or is it x, then y, then z? Have you tried: `$w = "xyz"; &myfunc($a_ref->{$w});` [download] ??	[reply] [d/l]
Re^2: Hash reference by koknat (Sexton) on Jun 03, 2005 at 23:27 UTC
Thanks very much. That worked. I didn't think the braces were needed, but they make all the difference. `&myfunc($a_ref->$w); # BAD &myfunc($a_ref->{$w}); # GOOD` [download] Yes, "xyz" was the key.	[reply] [d/l]
Re^3: Hash reference by monarch (Priest) on Jun 04, 2005 at 00:40 UTC
The braces are indeed important because you're providing a key, and expecting a value. The value is actually a reference! When you don't provide the braces you are no longer passing a key and expecting a value. Instead you're trying to call a function! That's why you get the error message, can't call method on unblessed reference.. because you have a hash, not an object.	[reply]
Re: Hash reference by djohnston (Monk) on Jun 03, 2005 at 22:31 UTC
If I understand you correctly, I think this is what you want: `myfunc($a_ref->{$w})`.	[reply] [d/l]