OpenEuphoria

Re: pbr vs multiple returns

• Posted by Chris Bensler <bensler at nt.net> Jan 11, 2007
• 571 views

Tommy Carlier wrote:
> 
> I also think the assignment of multiple values would be great. It would make
> Euphoria
> more functional. The stack code could look like this:
> }}}
<eucode>
> -- pushes o onto stack, and returns stack
> function push(sequence stack, object o)
>     return append(stack, o)
> end function
> 
> -- pops an object from the stack, and returns {stack, popped_object}
> function pop(sequence stack)
>     return { stack[1..$-1], stack[$] }
> end function
> 
> sequence s
> object o
> s = {}
> for i = 1 to 10 do
>     s = push(s, i)
> end for
> 
> for i = 1 to 10 do
>     {s, o} = pop(s)
> end for
> </eucode>
{{{

> That said, I also like the idea of PBR. I agree with Matt, that
> both the caller and callee have to specify the passing by reference.
> I don't really like the * notation of C/C++ (and OOEU?). I quite like the
> way it's done in C#, via the 'ref' keyword. In Euphoria, it could look like
> this:
> }}}
<eucode>
> procedure swap(ref object o1, ref object o2)
>     object o
>     o = o1
>     o1 = o2
>     o2 = o
> end procedure
> 
> integer a, b
> a = 1
> b = 2
> swap(ref a, ref b)
> </eucode>
{{{

> The stack code could look like this, with PBR:
> }}}
<eucode>
> procedure push(ref sequence s, object o)
>     s = append(s, o)
> end procedure
> 
> function pop(ref sequence s)
>     object o
>     o = s[$]
>     s = s[1..$-1]
>     return o
> end function
> 
> sequence s
> object o
> s = {}
> for i = 1 to 10 do
>     push(ref s, o)
> end for
> 
> for i = 1 to 10 do
>     o = pop(ref s)
> end for
> </eucode>
{{{

> To be honest, I actually like this PBR

I agree with Tommy's suggestions 100%
A keyword is better than a symbol. Either 'ref' or 'pbr'. 'pbr' might be less
likely to be confused with an actual parameter name.


Chris Bensler
~ The difference between ordinary and extraordinary is that little extra ~
http://empire.iwireweb.com - Empire for Euphoria