Variable Arguments

rikki cattermole via Digitalmars-d-learn digitalmars-d-learn at puremagic.com
Sat Apr 8 23:36:42 PDT 2017


On 09/04/2017 7:30 AM, Jethro wrote:
> void foo(A...)(A a)
> {
>     foreach(aa; a)
>     {
>         for(int i = 0; i < a.length; i++)
>             ...
>     }
> }
>
> A can be strings or char, how can I easily deal with both? (e.g.,
> a.length = 1 for a being a char... and also a[0] = a, so to speak).
>
> That is, I want chars to be treated as strings of length 1, since I have
> written my code to work with strings, no reason it shouldn't work with
> chars. I realize we can't use the above notation but I can't get the
> type of aa because D complains it is unknown at compile time. I could
> use A[k] but it requires extra work.

A char and a string is no where near the same thing.
A char is a single byte, a string is a array which is made up of a 
pointer to a set of chars plus a length (size_t WORD size of cpu e.g. 
4/8 bytes).

You would need to wrap up that input char e.g. string s = 
cast(immutable)[c];

But here is what I would recommend:

void foo(char[] c...) {
	string[] args;
	foreach(v; c) {
		args ~= cast(immutable)[c]
	}
	foo(args);
}

void foo(string[] s...) {
   // ...
}

This will remove the need for template specialization (or "implicit" 
support for e.g. wstring and dstring).


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