comment on

I like using pre- and post- conditions a lot of the time. The subroutine should say what it expects, and under what conditions you get a return value, etc. Something like:

sub add_one_to_number() {
  # add_one_to_number ($number) : takes a number, returns number + 1
  # PRE1:   number exists
  # POST1:  we return the number plus one
  my $number = shift;
  if (! defined $number) { 
    return undef; # fail PRE1
  }
  $number++;
  return $number; # success POST1
}
[download]

Okay, Noddy example, I know. It marks out under what conditions the author expected to reach these areas. If there is a bug at all, either it's because there is a precondition that we haven't thought about, or we don't successfully reach the postcondition (i.e., incorrect code). Also, putting in carps and things helps you track better what's going on if you follow the PREs and POSTs.

It's one of the things that works for me, anyway :) (obviously, this is in addition to all the other comments and stuff you make!!)

In reply to Re: Ways of commenting subroutines by kal
in thread Ways of commenting subroutines by stephen

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