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Exception catching sub

by bsb (Priest)
on Sep 02, 2003 at 08:57 UTC ( #288267=snippet: print w/ replies, xml ) Need Help??

Description: The "catch" sub below handles $@ after an eval { }.

I just came up with this today, so it's relatively untested and up for criticism.

PS. I know about Error.pm's funky extension syntax but the problems worry me.

# called just after an eval
sub catch {
  # don't catch if no error
  return 0 unless defined $@;
  
  # checks if $@->isa(one of the type in @_);
  UNIVERSAL::isa($@,$_) && return 1 for @_;
  
  # otherwise re-throws
  die $@;
}

# later on ...
while (my ($name,$val) = each %input) {
  if(eval { validate($val) }) { 
    $session->set($name, $val);

  } elsif(catch('ARRAY','E')) { 
    $errors{$name} = $@;        
    $action = 'reshow';
  } 
} 

# ...
eval { $nav->$action() } 
  or catch('E::Nav') and do { $error = $@; $nav->reshow };

# ... other things I haven't thought of ...

Comment on Exception catching sub
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Re: Exception catching sub
by simonm (Vicar) on Sep 02, 2003 at 18:28 UTC
    Automatically rethrowing (die $@) prevents you from catching several different types of exceptions in a series of elsifs -- I think you probably only want to rethrow if none of your catches match: if ( eval ... ) { ... } elsif ( catch("E") ) { ... } elsif ( catch("F") ) { ... } else { die $@; }
      Good point. Thanks.

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