How do you use templates in D?

[Andrew Pennebaker]

ntrel2<http://www.reddit.com/r/d_language/comments/lghzs/how_do_you_use_templates_in_d/>has
the answer:

char genChar() {
 return cast(char) uniform(0, 128);
}

T[] genArray(T)(T function() gen) {
 int len = uniform(0, 100);
T[] arr = [];

for(int i = 0; i < len; i++) {
 arr ~= gen();
}

return arr;
}

string genString() {
 return genArray(&genChar).idup;
}

Now I'm curious: How can I pass and accept a collection of lambdas? The
lambdas will each have different, arbitrary returns types. And how do I call
a function using a collection of values, something like Lisp's (apply f
args) ?

Cheers,

Andrew Pennebaker
www.yellosoft.us

On Tue, Oct 18, 2011 at 1:56 PM, Andrew Pennebaker <
andrew.pennebaker at gmail.com> wrote:

> I'm writing a function called genArray that accepts a function gen and
> returns a random array populated by calling gen(). genString builds on
> this by returning genArray(&genChar). But my type signatures are wrong.
>
> In dashcheck.d:
>
> char genChar() {
>     return cast(char) uniform(0, 128);
> }
>
> T[] genArray(T function() gen) {
>     int len = uniform(0, 100);
>     T[] arr = [];
>
>     for(int i = 0; i < len; i++) {
>         arr ~= gen();
>     }
>
>     return arr;
> }
>
> string genString() {
>     return genArray(&genChar);
> }
>
> Trace:
>
> dashcheck.d(17): Error: undefined identifier T
> dashcheck.d(17): Error: T is used as a type
> dashcheck.d(17): Error: undefined identifier T
> dashcheck.d(17): Error: T is used as a type
>
> Full code at GitHub <https://github.com/mcandre/dashcheck>
>
> Cheers,
>
> Andrew Pennebaker
> www.yellosoft.us
>
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