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  1. import std.stdio, std.typecons;
  2.  
  3. /* hack for 2.042 and older compilers (February 2010)
  4.  * present on ideone
  5.  */
  6. struct My_Tuple(T...)
  7. {
  8.     Tuple!T base;
  9.     alias base this;
  10.  
  11.     this(T args) { this.base = Tuple!T(args); }
  12.     U opIndex(U)(size_t idx) { return this.field[idx]; }
  13. }
  14.  
  15. My_Tuple!T make_tuple(T...)(T args)
  16. {
  17.     return typeof(return)(args);
  18. }
  19.  
  20. /* TESTING FUNCTION */
  21.  
  22. int[] foo(T...)(T args)
  23. {
  24.     writeln("Called foo ...");
  25.     foreach (i, arg; args)
  26.         writefln("    args[%d] == %s", i, arg);
  27.     writeln("... foo end");
  28.  
  29.     return [ 5, 10, 15, 20 ];
  30. }
  31.  
  32. /* UNPACKER */
  33.  
  34. auto unpack(alias fun, V...)(ref My_Tuple!V t)
  35. {
  36.     auto f(size_t i, U...)(U args)
  37.     {
  38.         static if (i == 0)
  39.             return fun(args);
  40.         else
  41.             return f!(i - 1)(t.field[i - 1], args);
  42.     }
  43.     return f!(V.length)();
  44. }
  45.  
  46. /* main */
  47.  
  48. void main()
  49. {
  50.     auto tup = make_tuple(
  51.         5, 3.14f, "hello world", [ 5, 10, 15 ], [ "foo":5, "bar":10 ]
  52.     );
  53.  
  54.     auto ret = unpack!foo(tup);
  55.     writeln("retval from foo: ", ret);
  56. }
  57.  
Success #stdin #stdout 0.01s 2152KB
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Standard input is empty
stdout
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Called foo ...
    args[0] == 5
    args[1] == 3.14
    args[2] == hello world
    args[3] == 5 10 15
    args[4] == [bar:10,foo:5]
... foo end
retval from foo: 5 10 15 20
https://ideone.com/jV5RM
language:
D (dmd 2.085.0)
created:
14 years ago
visibility:
public

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