in reply to difference between my and local

Imagine you have this:
# main scope
$fred = 1; #global
#...
{ # outer scope 
    my $fred = 2;
    #...
    { #inner scope
        #...
    }
}

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In the outer scope, you could argue you don't need local because you can theoretically assign a localised $fred to the value of global $fred with just my $fred = $fred;. But in the inner scope, local provides the only means of access to global $fred (other than referencing it by package name) because otherwise access to global $fred is blocked by the presence of outer scope's $fred.

-M

Free your mind

Replies are listed 'Best First'.
Re^2: difference between my and local
by Eimi Metamorphoumai (Deacon) on Nov 15, 2005 at 14:10 UTC
    I'm not quite sure what you're getting at, but you can certainly get the global value from anywhere, without using local. Observe: 
    # main scope
$fred = 1; #global
{ # outer scope
    my $fred = 2;
    #...
    { #inner scope
        print $main::fred; # prints the global 1
    }
}

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    The best rule of thumb is to use my unless you have some particular reason to use something else.
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[d/l]
[select]
      You'll find that my is used more often than local. So what I am getting at is that whereas my $fred = $fred will have the same effect as local $fred most of the time, it won't always. I expect the OP to wonder why he ever needs local instead of just using my $fred = $fred rather than to wonder why he needs my - he already knows why he needs my and he already knows broadly what both of these do.

      -M

      Free your mind

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