OpenEuphoria

Re: Goto (Was Re: Open Source)

• Posted by Chris Bensler <eu at creativeport??.ca> Oct 28, 2007
• 830 views

CChris wrote:
> 
> I'll try submitting shortly a set of Eu front end files that add a number of
> imho needed enhancements to the language. The additions are:
> * forward routine calls allowed, using
> }}}
<eucode>
> forward function f(integer z)
> n=f(3)
> --- some code here
> function f
> -- usual routine body here
> </eucode>
{{{


Is prototyping the way to go?
For functional purposes, it's not needed, afaik. It's purely for distinction,
correct?
Would it not be better to have some syntax that is used specifically for each
call to a forward reference?
Such as:
  n = ~f(3)

.. which makes it directly clear what is intended at the point it is used,
rather than the point at which it is defined.

> * new scope keyword, to declare variables local to part of a routine/top level
> code, possibly shadowing existing symbols;
> * nested routines are now supported. For consistency reasons, you can call
> only
> a routine which is a direct descendant of any ancestor of te current routine.
> * new loop
> }}}
<eucode>
> loop do
> -- some code
> until some_condition
> end loop
> </eucode>
{{{


> * exif exits an if block;

Can you give an example of how this would be used?

> * inside a oop, next skips the rest of the current iteration and performs any
> code prepring the next;
> * retry jumps to top of loop, without executing the code that prepares next
> iteration;
> * all loops can have a label attached to it, like this
> }}}
<eucode>
> for i=1 to n by 2 label "my string" do
> </eucode>
{{{

> * exif/exit/next/retry now have an optional parameter, either
> + a nuber of loop above current one (1 = loop above, 2=loop above the
> latter,...)
> + a negative number, to count loop levels backward (-1 = topmost loop, -2 =
> all but topmist,...)

I don't agree with the use of hard-coded exit values.
I beleive this would be extremely problematic.

> + a string, which must have been defined as a label prior;
> + the name of a for loop index.

I think I would personally opt for "exit to label" only.
It covers every case as well as reduces confusion and complexity.

> * defaulted routine parameters, with ability to default any parameter, not
> only
> the last one(s)
> 
> The only mod to backend would be to update be_syncolor.c so that the trace
> screen
> displays the new keywords as such.
> 
> I'll submit this to user contributions spùewhere in november. If I ever write
> some new code in Eu, I'll probably use and require that new interpreter. I'll
> attempt to also implement pass by reference, but this may or may not work. An
> earlier implementation I had just does no longer work with multitasking.
> 
> CChris

Chris Bensler
Code is Alchemy