OpenEuphoria

Re: modified interpreter

• Posted by Matt Lewis <matthewwalkerlewis at gmail.com> Jun 29, 2005
• 693 views

Kat wrote:
> 
> On 29 Jun 2005, at 3:40, Matt Lewis wrote:
> 
> > posted by: Matt Lewis 
> > 
> > Kat wrote:
> > > 
> > }}}
<eucode>
> >    :some_label
> >    puts(1, "Some label\n" )
> > 
> >    :another_label
> >    puts(1, "Another label\n" )
> > 
> >    g = "some_label"
> >    goto g -- same as goto "some_label"
> > </eucode>
{{{
</font>
> 
> That's a good example, yes. Not good coding style, but a good goto example 
> for what i meant. 


> > I think that if I were implementing this, I'd make the argument for goto
> > be some sort of value (i.e., not a label bareword).  
> 
> You mean not a string variable label? Ouch, i was going to use almost 
> exclusively strings!
> 
> > I'm not sure what
> > 'goto 5 + variable' means, though.
> 
> }}}
<eucode>
> integer x
> x = 12
> 
> puts(1,sprintf("%d",x)&"\n")
> 
> -- goto x 
> goto x + 3
> 
> :1
> :2
> puts(1,sprintf("%d",x)&"\n") goto end
> :3
> :12
> puts(1,sprintf("%d",x)&"\n") goto end
> :15
> puts(1,sprintf("%d",x)&"\n") goto end
> :end
> </eucode>
{{{
</font>
> 
> prints:
> 15
>
> Yes, another good example of rather bad coding AND the "evaluated goto" i 
> meant. The interesting part is, if the label isn't there, there's no error and
> it
> doesn't go anywhere. And if there's labels and no goto to call them, that's ok
>
> too! Makes a nice case (or switch) statement.

OK.  So a label is really an object.  I think that could work.  It's maybe 
possible to allow barewords, but then I don't think I should allow you
to pass a variable.  Doing both sounds like a recipe for trouble.  So to
goto a label, you could use:

goto "lable1"
goto "lable" & sprint(x)
:label1

> 
> I really believe this is a good idea also:
> 
> }}}
<eucode>
> function(sequence example)
> --code
> for loop = 1 to whatever do
>   -- code
>   while blah do
>      -- code
>      if zortched then goto end end if
>      -- code
>   end while -- blah
>   -- code
> end for -- whatever
> return blarg
> :end
> -- special zortched code
> end function
> <font color="#330033"></eucode>
{{{
</font>
> 
> The reason is it gets terribly non-normal exceptions out of the normal 
> program flow as it's read, plus it's faster and cleaner than flag vars being 
> constantly tested for "break"ing and "exit"ing or "continue"ing. It provides
> for
> a consistant block of zortch-handling code inside the function.
> 
> Naturally, any jump out of any loop, in any direction, resets the loop vars.

I don't think this is a problem.  In Eu, the loop vars get set inside the
loop, and you can ignore them otherwise, so it's just a jump.

No promises on time lines, though. :)
 
Matt Lewis