OpenEuphoria

Re: Variable Arguments?

• Posted by CChris <christian.cuvier at ag?iculture.gouv.f?> Apr 23, 2008
• 668 views

yuku wrote:
> 
> CChris wrote:
> > 
> > Jeremy Cowgar wrote:
> > > 
> > > CChris wrote:
> > > > 
> > > > The change was not trivial because it involves the ability to replay
> > > > canned
> > > > tokens after recording them. Indeed
> > > > procedure foo(integer n=n0)
> > > > needs late binding
> > > >
> > > 
> > > Even something as simple as:
> > > 
> > > }}}
<eucode>
> > > procedure foo(opt object n)
> > > </eucode>
{{{

> > > 
> > > and if n was not supplied, n defaulting to NULL would be a huge step.
> > > 
> > > }}}
<eucode>
> > > function round(sequence items, opt object n)
> > >   if n = NULL then n = 1 end if
> > >   ... code for round_precision ...
> > > end function
> > > </eucode>
{{{

> > > 
> > > That's not as good as function round(sequence items, integer precision=1)
> > > but,
> > > it's a huge step above what we have now and could be maintained later once
> > > an
> > > assignment would be possible.
> > > 
> > > How hard is something like that?
> > > 
> > What is NULL?
> > If we had a nil object, as I have advocated for a long time, then it would
> > be
> > ok. But adding nil is trickier I think - or not, I haven't tried yet. Moving
> > to 3-way logic might break too much code.
> 
> Instead of having a variable arguments or null type, I agree with JCougar,
> having default arguments will be easier to understand and easier to implement.
> 
> How about this syntax (as intuitive as possible)
> 
> [global] {function|procedure} <name> ( [<type> <name>]* [<type> <name> =
> <def>]*
> ) 
> 
> where <def> indicates default argument and it must be a constant!
> Default arguments also must be the last in the argument list.
> 
> Then, instead of modifying the back end, we can only modify the front end,
> to make it act like a preprocessor. e.g. for
> }}}
<eucode>
> global function round(object item, integer prec = 0)
> </eucode>
{{{

> 
> , if the call is like round(2.54), the front-end will emit IL that is 
> exactly the same as if the code were round(2.54, 0).
> 
> 
> yuku

But call_func(routine_id("round"),{2.54}) will need handling at runtime, ie in
backend.

CChris