Modifiable typesafe variadic arguments

[Daniel Keep]

BCS wrote:
> Deewiant wrote:
>> Daniel Keep wrote:
>>
>>> Honestly, I think that when you ever pass something to a function
>>> that it can
>>> change, there should be some explicit notice of this (like having to
>>> pass the
>>> argument by address).
>>
>>
>> I agree. Hence I still hope for my suggestion (which was originally
>> someone
>> else's idea, but I wrote it up at the D wish list,
>> http://all-technology.com/eigenpolls/dwishlist/ ) requesting usage of
>> explicit
>> out/inout when calling to be implemented. Meaning, whenever you call a
>> function
>> with out/inout arguments, you specify out/inout at the call point as
>> well as at
>> the function definition.
>>
>>
> On that thought, what is the easiest way to pass a copy in an inout arg
> or a dummy for an out?
> 
> this would be the effect, but its a bit verbose.
> 
> int  foo(inout int i, out int j)
> {
>     j = i;
>     i = 1;
>     return i+j;
> }
> ...
>     int i=1, k;
> ...
>     {    // don't care about i or j's returned value;
>         int i_ = i, j_;
>         k = foo(i_, j_);
>     }
> ...
> 
> something like this would be nice:
> 
> 
> ...
>     int i=1, k;
> ...
>     k = foo(i.dup, auto);
> ...

Or you could do what Visual Basic did: allow the programmer to pass an
immediate value as an 'inout' or 'out' parameter: in which case, it
stores the immediate value somewhere, calls the function, then discards
the value.

I've always found it somewhat amusing that VB is the only language I've
ever seen that allowed this nice little shortcut.  I can't decide if
that's because it's a bad idea, or because it's just really hard to do.

Knowing VB, it's probably the former.

	-- Daniel

-- 
Unlike Knuth, I have neither proven or tried the above; it may not even
make sense.

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