std.typetuple

Templates with which to manipulate type tuples (also known as type lists).

Some operations on type tuples are built in to the language, such as TL[n] which gets the nth type from the type tuple. TL[lwr .. upr] returns a new type list that is a slice of the old one.

References:
Based on ideas in Table 3.1 from Modern C++ Design, Andrei Alexandrescu (Addison-Wesley Professional, 2001)

Source:
std/typetuple.d

template TypeTuple(TList...)

Creates a typetuple out of a sequence of zero or more types.

Example:

 import std.typetuple;
 alias TypeTuple!(int, double) TL;

 int foo(TL td)  // same as int foo(int, double);
 {
    return td[0] + cast(int)td[1];
 }

Example:

 TypeTuple!(TL, char)
 // is equivalent to:
 TypeTuple!(int, double, char)

template IndexOf(T,TList...)

Returns the index of the first occurrence of type T in the sequence of zero or more types TList. If not found, -1 is returned.

Example:

 import std.typetuple;
 import std.stdio;

 void foo()
 {
    writefln("The index of long is ",
          IndexOf!(long, TypeTuple!(int, long, double)));
    // prints: The index of long is 1
 }

template Erase(T,TList...)

Returns a typetuple created from TList with the first occurrence, if any, of T removed.

Example:

 Erase!(long, int, long, double, char)
 // is the same as:
 TypeTuple!(int, double, char)

template EraseAll(T,TList...)

Returns a typetuple created from TList with the all occurrences, if any, of T removed.

Example:

 alias TypeTuple!(int, long, long, int) TL;

 EraseAll!(long, TL)
 // is the same as:
 TypeTuple!(int, int)

template NoDuplicates(TList...)

Returns a typetuple created from TList with the all duplicate types removed.

Example:

 alias TypeTuple!(int, long, long, int, float) TL;

 NoDuplicates!(TL)
 // is the same as:
 TypeTuple!(int, long, float)

template Replace(T,U,TList...)

Returns a typetuple created from TList with the first occurrence of type T, if found, replaced with type U.

Example:

 alias TypeTuple!(int, long, long, int, float) TL;

 Replace!(long, char, TL)
 // is the same as:
 TypeTuple!(int, char, long, int, float)

template ReplaceAll(T,U,TList...)

Returns a typetuple created from TList with all occurrences of type T, if found, replaced with type U.

Example:

 alias TypeTuple!(int, long, long, int, float) TL;

 ReplaceAll!(long, char, TL)
 // is the same as:
 TypeTuple!(int, char, char, int, float)

template Reverse(TList...)

Returns a typetuple created from TList with the order reversed.

Example:

 alias TypeTuple!(int, long, long, int, float) TL;

 Reverse!(TL)
 // is the same as:
 TypeTuple!(float, int, long, long, int)

template MostDerived(T,TList...)

Returns the type from TList that is the most derived from type T. If none are found, T is returned.

Example:

 class A { }
 class B : A { }
 class C : B { }
 alias TypeTuple!(A, C, B) TL;

 MostDerived!(Object, TL) x;  // x is declared as type C

template DerivedToFront(TList...)

Returns the typetuple TList with the types sorted so that the most derived types come first.

Example:

 class A { }
 class B : A { }
 class C : B { }
 alias TypeTuple!(A, C, B) TL;

 DerivedToFront!(TL)
 // is the same as:
 TypeTuple!(C, B, A)