- License
- Boost License 1.0.
- Authors
- Denis Shelomovskij
Type casting functions.
Functions from this module are intended to be used instead of build-in cast as they provide safer and richer interface.
template typesDynamicCastable(To, From)
@trusted inout(To) tryDynamicCast(To, From)(inout(From) o) if (typesDynamicCastable!(To, From));
@trusted bool dynamicCastable(To, From)(inout(From) o) if (typesDynamicCastable!(To, From));
@trusted inout(To) dynamicCast(To, From)(inout(From) o) if (typesDynamicCastable!(To, From));
template typesDowncastable(To, From)
@trusted inout(To) tryDowncast(To, From)(inout(From) o) if (typesDowncastable!(To, From));
@trusted bool downcastable(To, From)(inout(From) o) if (typesDowncastable!(To, From));
@trusted inout(To) downcast(To, From)(inout(From) o) if (typesDowncastable!(To, From));
template typesUpcastable(To, From)
@trusted inout(To) upcast(To, From)(inout(From) o) if (typesUpcastable!(To, From));
@trusted inout(void)* toRawPtr(From)(inout(From) o) if (is(From == class) || is(From == interface));
@system inout(To) fromRawPtr(To)(inout(void)* p) if (is(To == class) || is(To == interface));
- Preconditions:
- Passed object (pointer for fromRawPtr) is not null.
- Note:
- alias this isn't considered while casting in contrary to build-in cast.
Functions for class/interface dynamic casting.
These functions don't change type qualifier.
toRawPtr/fromRawPtr should be used to safely convert class instances
to raw void* instead of viewAs because interface variables
don't point to a beginning of a class instance.
class A { } class B { } A a = new A; Object o = a; assert(o.downcast!A is a); assert(!o.downcastable!B); static assert(!__traits(compiles, a.dynamicCast!B)); // cast impossible
interface I { } class A : I { } A a = new A; I i = a; void* p = a.toRawPtr; // `i` doesn't point to a beginning of a class instance: assert(i.viewAs!(void*) != p); assert(i.toRawPtr == p); assert(p.fromRawPtr!I is a); // `fromRawPtr` is `@system`
@system inout(To) viewAs(To, From)(inout(From) val);
@system inout(To) viewAs(To, From)(ref inout(From) val);
- Note:
- alias this isn't considered while casting in contrary to build-in cast.
- Warning:
- Resulting value may depend on target architecture.
Function allowing "blind" casting to any type of the same size.
No operations on actial value performed.
It is just treated as having different type.
These functions don't change type qualifier.
int i = 0; i.viewAs!(ubyte[4]) = 3; assert(i == 0x03030303);