Re: Catching a 'division by zero' error with Exception::Class

The exception even happens before the eval block is entered. This is because perl calculates immediate expressions during compile time. This should demonstrate it:

$ perl -lwe 'eval{0/0}'
Illegal division by zero at -e line 1.
[download]

To work around that, you can try putting 0 into a variable.

Comment on Re: Catching a 'division by zero' error with Exception::Class Download Code

Replies are listed 'Best First'.
Re^2: Catching a 'division by zero' error with Exception::Class by moritz (Cardinal) on Sep 15, 2008 at 15:45 UTC
The exception even happens before the eval block is entered. This is because perl calculates immediate expressions during compile time. That's only true for older perls: `$ perl5.10.0 -ce '1/0' -e syntax OK $ perl5.8.8 -ce '1/0' Illegal division by zero at -e line 1.` [download] (I think it was intentionally removed in newer perls because it could break code even if it's not reachable; consider this example: `my $DEBUG = 0; ... if ($DEBUG) { $verbosity = 10 / $DEBUG; }` [download] in which case constant folding might break things). (Update: in that last example there is no constant folding at all, because variables are not constant folded. ikegami suggested to `use constant DEBUG => 0;` instead, which should better demonstrate what I was thinking about).	[reply] [d/l] [select]

Replies are listed 'Best First'.

Re^2: Catching a 'division by zero' error with Exception::Class
by moritz (Cardinal) on Sep 15, 2008 at 15:45 UTC

The exception even happens before the eval block is entered. This is because perl calculates immediate expressions during compile time.

That's only true for older perls:

$ perl5.10.0 -ce '1/0'
-e syntax OK
$ perl5.8.8 -ce '1/0'
Illegal division by zero at -e line 1.
[download]

(I think it was intentionally removed in newer perls because it could break code even if it's not reachable; consider this example:

my $DEBUG = 0;
...

if ($DEBUG) {
   $verbosity = 10 / $DEBUG;
}
[download]

in which case constant folding might break things).

(Update: in that last example there is no constant folding at all, because variables are not constant folded. ikegami suggested to use constant DEBUG => 0; instead, which should better demonstrate what I was thinking about).

[reply]
[d/l]
[select]