Re: why doesn't this work?

[Eric Amick]

On Mon, 27 Sep 2004 12:05:10 -0700, you wrote:

>================
>test script:
>================
>use strict;
>use testlib;
>
>print("Env Var 'Oracle' is set to '$ENV{Oracle}'\n");
>callme();
>
>================
>test library (testlib.pm):
>================
>use strict;
>
>if ($ENV{Oracle}) {
>       sub callme {print("Version 1\n");}
>       }
>else {
>       sub callme {print("Version 2\n");}
>       }

Normal subroutine definitions occur at compile time, so the second
definition overrides the first before the code even executes. You can do
this instead:

if ($ENV{Oracle}) {
        eval 'sub callme {print("Version 1\n");}'
        }
else {
        eval 'sub callme {print("Version 2\n");}'
        }

or this:

if ($ENV{Oracle}) {
        $callme = sub {print("Version 1\n");}
        }
else {
        $callme = sub {print("Version 2\n");}
        }

or even this:

if ($ENV{Oracle}) {
        *callme = sub {print("Version 1\n");}
        }
else {
        *callme = sub {print("Version 2\n");}
        }

In any case, you will need either an argument list or an ampersand when
calling callme(), since Perl won't know the type at compile time. (The
second case would need $callme->() or &$callme.)

-- 
Eric Amick
Columbia, MD

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