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Struct `std.typecons.Typedef`

Typedef allows the creation of a unique type which is based on an existing type. Unlike the alias feature, Typedef ensures the two types are not considered as equals.


						
				struct Typedef(T, T init = T.init, string cookie = null)
				;

Example

alias MyInt = Typedef!int;
static void takeInt(int) { }
static void takeMyInt(MyInt) { }

int i;
takeInt(i);    // ok
takeMyInt(i);  // fails

MyInt myInt;
takeInt(myInt);    // fails
takeMyInt(myInt);  // ok

Parameters

Name Description

init Optional initial value for the new type. For example: ---- alias MyInt = Typedef!(int, 10); MyInt myInt; assert(myInt == 10); // default-initialized to 10 ----

cookie Optional, used to create multiple unique types which are based on the same origin type T. For example: ---- alias TypeInt1 = Typedef!int; alias TypeInt2 = Typedef!int; // The two Typedefs are the same type. static assert(is(TypeInt1 == TypeInt2)); alias MoneyEuros = Typedef!(float, float.init, "euros"); alias MoneyDollars = Typedef!(float, float.init, "dollars"); // The two Typedefs are _not_ the same type. static assert(!is(MoneyEuros == MoneyDollars)); ----

Name	Description
init	Optional initial value for the new type. For example: ---- alias MyInt = Typedef!(int, 10); MyInt myInt; assert(myInt == 10); // default-initialized to 10 ----
cookie	Optional, used to create multiple unique types which are based on the same origin type `T`. For example: ---- alias TypeInt1 = Typedef!int; alias TypeInt2 = Typedef!int; // The two Typedefs are the same type. static assert(is(TypeInt1 == TypeInt2)); alias MoneyEuros = Typedef!(float, float.init, "euros"); alias MoneyDollars = Typedef!(float, float.init, "dollars"); // The two Typedefs are _not_ the same type. static assert(!is(MoneyEuros == MoneyDollars)); ----

Note

If a library routine cannot handle the Typedef type, you can use the TypedefType template to extract the type which the Typedef wraps.

Authors

Andrei Alexandrescu, Bartosz Milewski, Don Clugston, Shin Fujishiro, Kenji Hara

License

Boost License 1.0.