OpenEuphoria

Re: Goto (Was Re: Open Source)

• Posted by Juergen Luethje <j.lue at g?x?de> Oct 26, 2007
• 832 views

Pete Lomax wrote:

> Juergen Luethje wrote:
> > 
> > this is my translated code (untested):
> 
> Your code worked perfectly on the second test set, and gave initially correct
> answers on the first set, before yielding negative highvalues...
> 
> I toyed with the idea of challenging you to find the bug 
> 
> The mistake you made is this:
> > Pete Lomax wrote:
> > > Try this then:
> > > function find_combination(integer jumpToDa200)
> > >     if jumpToDa200 then goto da200 end if
> > > da200::
> you translated this as:
> > 
> > function find_combination(integer jumpToDa200)
> >    if not jumpToDa200 then
> >    end if
> >    while 1 do
> >       if not jumpToDa200 then
> >       end if
> >       if jumpToDa200 or flag = TRUE then
> <da200:: was here>
> >       end if
> >    end while      
> > 
> The original jumped to da200 from the top of the routine, whereas you test the
> parameter again on every iteration around the loop. Clearing the flag at the
> point where the label used to be fixes it.

I see.

>  From the number of tests it passed despite this flaw, I feel lucky to have
> spotted it at all.
> 
> > I created code for Matt's OOEU, which does support GOTO. Then I removed
> > the GOTOs step by step and so in the end I had a program for the
> > standard Eu interpreter.
> Not really the answer though, installing two different interpreters, is it?

Up to now, I have encountered this special problem only once. Since I
registered Euphoria in April 2002, this means only once in 5+ years --
pretty much the same what you wrote. And in this rare situation I used
an appropriate tool to solve the special problem. That was/is fine with
me.
What is the answer in your opinion?

Regards,
   Juergen


PS: IMHO it would be very cool if there were a kind of pre-processor,
that could automagically translate GOTOs into more structured code.
This would be a nice challenge for you and other "senior programmers",
no? 
(I am curious whether this is actually possible from a theoretical point
of view.)