use Perl

• critic to the rescue (Score:1)

  by daxim (8218)

  The problem of needing to localise special variables is discussed in http://perldoc.perl.org/perlobj.html#Destructors [perl.org].

  There is a P::C policy ErrorHandling::RequireCheckingReturnValueOfEval [cpan.org] that catches this programming mistake. Its documentation also offers an alternative approach where you don't need to mess with other people's destructors to make it work.

  package SomeClass;
  sub new {
      return bless \my $foo => __PACKAGE__;
  }
  
  sub DESTROY {
      eval {'resetting $@'};
  }
  
  package main;
  use
  • Re: (Score:1)

    by davebaker (4482)

    Did you mean to say

    if (
        eval {
            my $obj = SomeClass->new();
            die "Code Red!\n";
            1;
        }
    ) {
        print "No exception occurred\n";
    } else {
        print "Exception caught: $@\n";
    }
• How? (Score:1)

  by Downes (9057)

  > use local($@) to restore the previous value of $@ when your routine completes. How? (Searched web but didn't find an answer)
  • Re: (Score:1)

    by Aristotle (5147)

    Err. How what?

    local $@;

    Just like he said.
• Thanks (Score:1)

  by Downes (9057)

  Thanks. (This shows the danger of just mixing in code with plain English when you're explaining things; sometimes people don't recognize that it *is* code (even though it's obvious to others))
• eval {} or do_something (Score:1)

  by davebaker (4482)

  Following the eval block with an "or" seems to be more reliable than using "if ($@)" to check for an exception in an eval block, because an eval block (or even an eval EXPR) returns undef if there is a syntax error or runtime error or a die statement is executed (according to perldoc -f eval).

  
        eval {
                my $obj = SomeClass->new();
                die "Code Red!\n";