std.traits - D Programming Language - Digital Mars

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Last update Wed Sep 2 00:11:33 2009

# std.traits

Templates with which to extract information about types at compile time.

template ReturnType(alias dg)
template ReturnType(dg)
  Get the type of the return value from a function, a pointer to function, or a delegate.
  Example:

       import std.traits;
       int foo();
       ReturnType!(foo) x;   // x is declared as int

template ParameterTypeTuple(alias dg)
template ParameterTypeTuple(dg)
  Get the types of the paramters to a function, a pointer to function, or a delegate as a tuple.
  Example:

       import std.traits;
       int foo(int, long);
       void bar(ParameterTypeTuple!(foo));      // declares void bar(int, long);
       void abc(ParameterTypeTuple!(foo)[1]);   // declares void abc(long);

template FieldTypeTuple(S)
  Get the types of the fields of a struct or class. This consists of the fields that take up memory space, excluding the hidden fields like the virtual function table pointer.
template BaseTypeTuple(A)
  Get a TypeTuple of the base class and base interfaces of this class or interface.
  Example:

       import std.traits, std.typetuple, std.stdio;
       interface I { }
       class A { }
       class B : A, I { }

       void main()
       {
           alias BaseTypeTuple!(B) TL;
           writefln(typeid(TL));	// prints: (A,I)
       }

template isStaticArray(T)
  Detect whether type T is a static array.
template isExpressionTuple(T...)
  Tells whether the tuple T is an expression tuple.

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