Re: Re: Re: static-like persistence of my variable due to trailing conditional

The reason we cant give an error is because my $foo = "blah" only gets executed if $var is true. However, we dont actually know if $var is true or not until runtime.

So when you call mycode() with no arguments then my $foo = 'blah' is not executed at all. Instead, simply $foo = 'FOO' gets executed, setting $main::foo (you can verify this by printing out $main::foo after you call mycode() with no arguments).

use strict is only supposed to catch compile-time errors (according to its documentation). It should not blow up at runtime.

To do what you expect here you could do something like:


    my $foo = defined $var ? 'blah' : 'FOO';

or even:


    my $foo;
    if ($var) {
        $foo = 'blah';
    }
    else {
        $foo = 'FOO';
    }

Comment on Re: Re: Re: static-like persistence of my variable due to trailing conditional

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Re^4: static-like persistence of my variable due to trailing conditional by Aristotle (Chancellor) on Jun 30, 2002 at 17:45 UTC
my $foo = 'blah' is not executed at all. Instead, simply $foo = 'FOO' gets executed, setting $main::foo (you can verify this by printing out $main::foo after you call mycode() with no arguments). Wrong. Actually, the fact that `$foo` is scoped lexically must be known at compile time - think about it, how else would strict work? After the compiler sees a `my`, it generates ops referring to lexicals rather than globals for the variables. However, allocation of these lexicals happens at runtime. By adding an `if`, you prevent the allocation at runtime, but you do not prevent the lexical scoping that happens at compile time. The effect is that subsequent invocations of the routine refer to a lexically scoped scalar that was allocated in a previous invocation - the same way as closures do. Makeshifts last the longest.	[reply]
Re: Re: Re: Re: static-like persistence of my variable due to trailing conditional by meonkeys (Chaplain) on Jun 30, 2002 at 17:17 UTC
I concur, except for this part: So when you call `mycode()` with no arguments then `my $foo = 'blah'` is not executed at all. Instead, simply `$foo = 'FOO'` gets executed, setting `$main::foo` (you can verify this by printing out $main::foo after you call mycode() with no arguments). I had a line in my original code that dumped the symbol table: `print Dumper(\%main::);` But threw this out because I am never able to see `$foo` in the symbol table for the main package. Are you? --- "A Jedi uses the Force for knowledge and defense, never for attack."	[reply]