Well, technically what is happening is not violating Camel III. See, it *does* get its own scratchpad, which can be quickly checked by: 
    #!/opt/perl/bin/perl -w
    use strict;
    sub foo;
    sub foo {
        return unless $_ [0];
        my $x if 0;
        print ++ $x, " ";
        foo $_ [0] - 1;
    }
    
    foo 1; print "\n";
    foo 2; print "\n";
    foo 3; print "\n";
    foo 4; print "\n";
    __END__
    1 
    2 1 
    3 2 1 
    4 3 2 1

[download]
Scary, isn't? When the subroutine recurses, it notices there is still a reference to $x and hence it will create a new scratchpad. But when there is no reference, it will reuse an old scratchpad....

I do agree that using my in this way doesn't tend to lead to well understood code. I wouldn't go as far as to say it's never useful, but such cases will be very rare and it's not a technique I would teach in my classes.

-- Abigail

In reply to Re: Unusual Closure Behaviour by Abigail
in thread Unusual Closure Behaviour by tachyon

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