From: Claus Spitzer <DocBoobenstein@...>
Date: 2004-05-20T02:57:50+09:00
Subject: Re: How to duck type? - the psychology of static typing in Ruby

8< ----- snip -----
 
> As good as a code coverage tool is, it still only works with running
> code.  It will tell you what areas aren't being used regularly, but then
> you have to find a way to check them.
> 
> What I'm looking for is more what another poster mentioned:
> 
> > A better example is that perl does exactly what you were asking for
> > otherwise (behavior when -c and -v are both supplied to the ruby
> > interpreter):
> >
> > jenova ~ % cat -n what.pl
> >      1  $num = 3;
> >      2  $num += 2;
> >      3  if ($numb != 5) {
> >      4       print "Foo!!\n";
> >      5  }
> > jenova ~ % perl -cw what.pl
> > Name "main::numb" used only once: possible typo at what.pl line 3.
> > what.pl syntax OK
> 
> At no point does it try to run the code, but it still finds that
> potential trouble spot.
> 
> I think unit tests are great, so are code coverage tools, as are
> profilers and debuggers... but I still see a need for 'typo catchers'.
> 
> Ben
> 
> 

I'm just speculating here, but could perhaps a reason why it is
difficult to implement such a thing be that because, unlike Perl, Ruby
implements reflection [see "Concepts and Experiments in Computational
Reflection", Pattie Maes, 1997] at least to some degree? As
aforementioned this is just speculation of mine and not based on
anything but my understanding of Ruby's nature; perhaps Matz can
enlighten us on that. But if reflection _is_ implemented then complete
typo checking could be near impossible because the code would be able
to change itself during execution (including creating new objects).
Keep in mind though that I said _complete_ typo checking - checking of
object names previous to compilation shouldn't be that difficult,
albeit not complete.
Anyway, that's just my $0.02. It could turn out that I'm completely
wrong. Feel free to point out any fallacy in the above line of reason
- I've never refused an opportunity to correct my knowledge as of yet.
Cheers!
   -Claus