Is there any way to assign multiple variable at once with Dlang?

Question

With using Ruby, we can do this.

s = "split by space"
A,B,C = s.split(" ").map(&:to_i)

With using D-lang, it's compile error.

string s = "split by space";
int A,B,C = s.split(" ").map!(x => x.to!int);

Answer 1

Jonathan is mostly right, but there is in fact a way to split a tuple into its constituent parts, albeit more verbose than in Ruby, and without any handy type inference:

import std.meta : AliasSeq;
import std.typecons : tuple;

auto foo() { return tuple(42, 29, "hello"); }

unittest {
   int a, b;
   string c;
   AliasSeq!(a, b, c) = foo(); // Look ma, magic!
   assert(a == 42);
   assert(b == 29);
   assert(c == "hello");
}

While there's no built-in way to do this with ranges like your example, it's possible to implement in a library:

import std.meta : AliasSeq, Repeat;
import std.typecons : Tuple, tuple;
import std.algorithm : map;
import std.conv : to;
import std.string : split;
import std.range : isInputRange, ElementType;

unittest {
   string s = "1 2 3";
   int A,B,C;
   AliasSeq!(A,B,C) = s.split(" ").map!(x => x.to!int).tuplify!3;
   assert(A == 1);
   assert(B == 2);
   assert(C == 3);
}

auto tuplify(size_t n, R)(R r) if (isInputRange!R) {
   Tuple!(Repeat!(n, ElementType!R)) result;

   static foreach (i; 0..n) {
      result[i] = r.front;
      r.popFront();
   }
   assert(r.empty);

   return result;
}