Hello everybody

Yesterday, debugging a program I was writing, I thought I spotted a problem in an eval.

It is a common practice to trap exceptions with code blocks like the following:

eval {
  # some perl code here
  . . . 
}

if ($@) {
  print "eval failed: $@\n\n" ;
}

[download]

and the one I was in was quite similar to the above. I went back to the documentation and double checked if I remembered exactly eval's syntax. A small section made a bell sound in my head:

               If there is a syntax error or runtime error, or a "die"
+ state-
               ment is executed, an undefined value is returned by "ev
+al", and
               $@ is set to the error message.  If there was no error,
+ $@ is
               guaranteed to be a null string.

[download]

So, actually, a failed eval returns undef and sets $@. Ok, but...

The question is: it is easy to have an eval succeed (hence setting $@ and return undef, but is it possible to have a failing eval to return a null $@?

Ciao!
--bronto

The very nature of Perl to be like natural language--inconsistant and full of dwim and special cases--makes it impossible to know it all without simply memorizing the documentation (which is not complete or totally correct anyway).
--John M. Dlugosz

In reply to seeking eval failures by bronto

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