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Function `std.algorithm.mutation.moveEmplace`

Similar to move but assumes target is uninitialized. This is more efficient because source can be blitted over target without destroying or initializing it first.


						
				void moveEmplace(T)
				(
				

				  ref T source,
				

				  ref T target
				

				) pure @system;

Parameters

Name	Description
source	value to be moved into target
target	uninitialized value to be filled by source

Example

static struct Foo
{
pure nothrow @nogc:
    this(int* ptr) { _ptr = ptr; }
    ~this() { if (_ptr) ++*_ptr; }
    int* _ptr;
}

int val;
Foo foo1 = void; // uninitialized
auto foo2 = Foo(&val); // initialized
assert(foo2._ptr is &val);

// Using `move(foo2, foo1)` would have an undefined effect because it would destroy
// the uninitialized foo1.
// moveEmplace directly overwrites foo1 without destroying or initializing it first.
moveEmplace(foo2, foo1);
assert(foo1._ptr is &val);
assert(foo2._ptr is null);
writeln(val); // 0

Authors

Andrei Alexandrescu

License

Boost License 1.0.