APM: Dumb program acting funny...

[Mike Stok]

On 19-Oct-06, at 1:14 AM, Bill Raty wrote:

> You have warnings enabled 'the -w switch on shebang'.
>
> With warnings enabled perl will output a message whenever it  
> detects an undefined value in a join or string interpolation.  To  
> demonstrate:
>
>   use warnings;
>   use strict;
>
>   my $empty = undef;
>   print "Perl will warn about this $empty string.\n";
>
> I rarely use warnings in production code.  It is better to locally  
> scope warnings in code sections where you are certain you must  
> always have data that is not null.
>

I usually work the other way around, using warnings everywhere, and  
then using no warnings as tightly scoped as possible to mark where I  
know uninitialized variables and perl's treatment of them are OK

use strict;
use warnings;

my $empty = undef;
{
     no warnings 'uninitialized';
     print "Perl will not warn about this $empty string.\n";
}

(Let's not notice that $empty is initialized in this code, so the  
warning is misleading.)

The same goes for using "no strict 'refs';"  around code where I  
might be using strings to manipulate the symbol table.

The lexical relaxation reminds me later that I was doing something  
"odd" in this chunk of code.


Mike

-- 

Mike Stok <mike at stok.co.uk>
http://www.stok.ca/~mike/

The "`Stok' disclaimers" apply.




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