• Jack Applegame (14/14) Aug 06 2013 In C++11 we can write:
• Jack Applegame (3/3) Aug 06 2013 In other words, I need something like this:
• bearophile (6/9) Aug 06 2013 Sorry, your second post was not yet present and I misunderstood
• Jack Applegame (2/3) Aug 06 2013 staticMap works with types, and I don't know how it can help.
• Dicebot (4/7) Aug 06 2013 Not really. Anything that can be provided to template argument
• Jack Applegame (14/21) Aug 06 2013 Yes. Types, literals and aliases. But this doesn't help.
• Artur Skawina (36/42) Aug 06 2013 The problem is more that staticMap requires a *template*, not a
• bearophile (4/5) Aug 06 2013 somefunc(process(args));

"Jack Applegame" <japplegame gmail.com> writes:

In C++11 we can write:

     template<class... Args>
     void somefunc(Args... args {
         ...
     }

     template<class T>
     T process(T p) {
         ...
     }

     template <class... Args>
     void foo(Args... args) {
         somefunc(process(args)...);
     }

Is there a simple way to do this in D?

"Jack Applegame" <japplegame gmail.com> writes:

In other words, I need something like this:

foo(magicTemplate!(f, a1, a2, a3...)) === foo(f(a1), f(a2), 
f(a3)...)

"bearophile" <bearophileHUGS lycos.com> writes:

Jack Applegame:

 In other words, I need something like this:

 foo(magicTemplate!(f, a1, a2, a3...)) === foo(f(a1), f(a2), 
 f(a3)...)

Sorry, your second post was not yet present and I misunderstood 
your question.

Take a look at std.typetuple.staticMap

Bye,
bearophile

"Jack Applegame" <japplegame gmail.com> writes:

On Tuesday, 6 August 2013 at 14:44:18 UTC, bearophile wrote:
 Take a look at std.typetuple.staticMap

staticMap works with types, and I don't know how it can help.

"Dicebot" <public dicebot.lv> writes:

On Tuesday, 6 August 2013 at 15:51:28 UTC, Jack Applegame wrote:
 On Tuesday, 6 August 2013 at 14:44:18 UTC, bearophile wrote:
 Take a look at std.typetuple.staticMap

 staticMap works with types, and I don't know how it can help.

Not really. Anything that can be provided to template argument 
list can be stored in TypeTuple and thus processed by staticMap. 
Name is very confusing here.

"Jack Applegame" <japplegame gmail.com> writes:

On Tuesday, 6 August 2013 at 16:03:07 UTC, Dicebot wrote:
 On Tuesday, 6 August 2013 at 15:51:28 UTC, Jack Applegame wrote:
 On Tuesday, 6 August 2013 at 14:44:18 UTC, bearophile wrote:
 Take a look at std.typetuple.staticMap

 staticMap works with types, and I don't know how it can help.

 Not really. Anything that can be provided to template argument 
 list can be stored in TypeTuple and thus processed by 
 staticMap. Name is very confusing here.

Yes. Types, literals and aliases. But this doesn't help.

I wrote very ugly, but working solution. I don't like it, but I 
can't invent something better. :(

auto apply(alias p, alias f, Args...)(Args args) {
     auto impl(uint num, Head, Tail...)(Head head, Tail tail) {
         static if(num == 0) return p(head, tail);
         else return impl!(num - 1)(tail, f(head));
     }
     return impl!(args.length)(args);
}

apply!(fun1, fun2)(arg1, arg2, ...) === fun1(fun2(arg1), 
fun2(arg2), ...)

offtop: Dicebot, do you speak russian?

Artur Skawina <art.08.09 gmail.com> writes:

On 08/06/13 18:03, Dicebot wrote:
 On Tuesday, 6 August 2013 at 15:51:28 UTC, Jack Applegame wrote:
 On Tuesday, 6 August 2013 at 14:44:18 UTC, bearophile wrote:
 Take a look at std.typetuple.staticMap

 staticMap works with types, and I don't know how it can help.

 
 Not really. Anything that can be provided to template argument list can be
stored in TypeTuple and thus processed by staticMap. Name is very confusing
here.

The problem is more that staticMap requires a *template*, not a
function. Another one is that doing it like that (ie storing the
intermediate results in a tuple or struct) creates unnecessary
copies -  which isn't really an issue for small PODs, because the
compiler optimizes most of the overhead away, but can have a
significant cost when handling types w/ nontrivial cpctors etc.

Anyway, there are several ways to do this in D. One example:

   void foo(Args...)(Args args) {
       mixin(evalExpMap!(q{ somefunc(%...); }, q{ process(%s) }, args));
         // == `somefunc(process(args[0]), process(args[1]), etc);`
   }

   // or

   void foo(Args...)(Args args) {
       auto result = mixin(evalExpMap!(q{ somefunc(%...) }, q{ process(%s) },
args));
       //...
   }

   // and the helper:

   template evalExpMap(string C, string F, A...) {
      enum evalExpMap = {
         import std.array, std.conv;
         string s, l;
         static if (is(typeof(A))) alias B = typeof(A);
                else               alias B = A;
         foreach (I, _; B) {
            auto r = replace( replace(F, "%s", A[I].stringof),
                                         "%d", to!string(I));
            l ~= (I?", ":"") ~ r;
            s ~=               r ~ ";\n";
         }
         return replace(replace(C, "%...;", s), "%...", l);
      }();
   }

Not as simple as the C++ equivalent. But not that much more
complicated and *much* more powerful.

artur

"bearophile" <bearophileHUGS lycos.com> writes:

Jack Applegame:

 Is there a simple way to do this in D?

somefunc(process(args));

Bye,
bearophile