Perl subroutine references

I just found this useful for generating a dispatch/lookup table. You can create a hash table with the values being references to subroutines.

Here's a simple example:

> perl -le '$a = sub { 5 * $_[0]};print &{$a}(23);'
> 115

A better example is to use this as a look-up table. Here's another simple example:

%table = (
 "+" => sub { $_[0] + $_[1] },
 "-" => sub { $_[0] - $_[1] },
 "*" => sub { $_[0] * $_[1] },
 "/" => sub { $_[0] / $_[1] },
);

print &{$table{"+"}}(12,24), "\n";
print &{$table{"-"}}(24,12)), "\n";

This would output 36 and 12 respectively. This is very handy for more complex processing and parsing (which is what I'm using it for).