emplace

Given a raw memory area chunk, constructs an object of class type T at that address. The constructor is passed the arguments Args. If T is an inner class whose outer field can be used to access an instance of the enclosing class, then Args must not be empty, and the first member of it must be a valid initializer for that outer field. Correct initialization of this field is essential to access members of the outer class inside T methods. Preconditions: chunk must be at least as large as T needs and should have an alignment multiple of T's alignment. (The size of a class instance is obtained by using __traits(classInstanceSize, T)). Note: This function can be @trusted if the corresponding constructor of T is @safe.

T* emplace(T* chunk)
T* emplace(T* chunk, Args args)
T emplace(T chunk, Args args)
T emplace(void[] chunk, Args args)
T
emplace
(
T
Args...
)
(
void[] chunk
,
auto ref Args args
)
if (
is(T == class)
)
T* emplace(void[] chunk, Args args)

Return Value

Type: T

The newly constructed object.

Examples

static class C
{
    int i;
    this(int i){this.i = i;}
}
auto buf = new void[__traits(classInstanceSize, C)];
auto c = emplace!C(buf, 5);
assert(c.i == 5);

// works with -betterC too:

static extern (C++) class C
{
    @nogc pure nothrow @safe:
    int i = 3;
    this(int i)
    {
        assert(this.i == 3);
        this.i = i;
    }
    int virtualGetI() { return i; }
}

align(__traits(classInstanceAlignment, C)) byte[__traits(classInstanceSize, C)] buffer;
C c = emplace!C(buffer[], 42);
assert(c.virtualGetI() == 42);

emplace

Return Value

Examples

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