local doesn't actually create a local variable. That's what my does.

At least, that's what perlsub says.

Here's what I tried:

#!/usr/bin/perl -w

use strict;

# local %hash;    # gives error
my %hash;    # no error

{
    local %hash;    # no error, if %hash previously declared with my
#    local %hash;    # error if %hash previously undeclared
}
[download]

local and my are completely different. What local does is, within its scope, save the previous value of a defined variable, restoring it when you leave the enclosing scope. Dominus has a nice article on the uses of local, and I'll see if I can find it before someone else posts a pointer.

Update: chipmunk and tilly are both right. I should have put use vars ( %hash ); instead of my. But the main point still stands.