Some questions

[Deewiant]

bearophile wrote:
 > 2) Do you know why the following isin2() doesn't work?
>
> class Gen {
>   int stop;
>   this(int instop) { stop = instop; }
>   int opApply(int delegate(ref int) dg) {
>     int result;
>     for (int i = 0; i < stop; i++) {
>       result = dg(i);
>       if (result) break;
>     }
>     return 0;
>   }
> }
> bool isin1(Gen items, int el) {
>   bool result = false;
>   foreach(el2; items)
>     if (el == el2) {
>       result = true;
>       break;
>     }
>   return result;
> }
> bool isin2(Gen items, int el) {
>   foreach(el2; items)
>     if (el == el2)
>       return true;
>   return false;
> }
> void main() {
>   assert(isin1(new Gen(10), 5) );
>   assert(!isin1(new Gen(10), 20) );
>   assert(isin2(new Gen(10), 5) );
>   assert(!isin2(new Gen(10), 20) );
> }

You're returning 0, instead of result, in opApply.

> 4) This code:
> foreach (k, v; ["ab":12])
>     putr(k, ' ', v);
>
> Gives me this error:
> Error: cannot have out or ref parameter of type char[2u]
> Is this a bug of DMD, or some limitation I have to know about?

"ab" is of type char[2]. If you want a char[] (and you do), write "ab"[] or the
more verbose cast(char[])"ab".

putr evidently takes its third parameter as inout/out/ref, but you can't do that
with static arrays, as the error message says. You need to pass a dynamic array
instead.

> 5) Is this a bug of the function overload system? If the static if is set to
> false it gives an error, the only difference is in the order of the
> definitions of the overloard alternative() function:
>
> import std.stdio;
>
> int fun(TyElem)(TyElem[] arr) {
>     return arr.length;
> }
>
> static if (true) { // change this
>     alias fun!(char) alternative;
>     int alternative(int[] arr) {
>         return arr[0];
>     }
> } else {
>     int alternative(int[] arr) {
>         return arr[0];
>     }
>     alias fun!(char) alternative;
> }
>
> void caller(TyOp)(TyOp op, char[] s) {
>     writefln( op(s) );
> }
>
> void main() {
>     caller(&alternative, "abc"); // prints 3
> }
>

It's a bug, probably 810: http://d.puremagic.com/issues/show_bug.cgi?id=810

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