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Function `std.experimental.allocator.make`

Dynamically allocates (using alloc) and then creates in the memory allocated an object of type T, using args (if any) for its initialization. Initialization occurs in the memory allocated and is otherwise semantically the same as T(args). (Note that using alloc.make!(T[]) creates a pointer to an (empty) array of Ts, not an array. To use an allocator to allocate and initialize an array, use alloc.makeArray!T described below.)


						
				auto make(T, Allocator, A...)
				(
				

				  auto ref Allocator alloc,
				

				  auto ref A args
				

				);

Parameters

Name	Description
T	Type of the object being created.
alloc	The allocator used for getting the needed memory. It may be an object implementing the static interface for allocators, or an `IAllocator` reference.
args	Optional arguments used for initializing the created object. If not present, the object is default constructed.

Returns

If T is a class type, returns a reference to the created T object. Otherwise, returns a T* pointing to the created object. In all cases, returns null if allocation failed.

Throws

If T's constructor throws, deallocates the allocated memory and propagates the exception.

Example

// Dynamically allocate one integer
const int* p1 = theAllocator.make!int;
// It's implicitly initialized with its .init value
writeln(*p1); // 0
// Dynamically allocate one double, initialize to 42.5
const double* p2 = theAllocator.make!double(42.5);
writeln(*p2); // 42.5

// Dynamically allocate a struct
static struct Point
{
    int x, y, z;
}
// Use the generated constructor taking field values in order
const Point* p = theAllocator.make!Point(1, 2);
assert(p.x == 1 && p.y == 2 && p.z == 0);

// Dynamically allocate a class object
static class Customer
{
    uint id = uint.max;
    this() {}
    this(uint id) { this.id = id; }
    // ...
}
Customer cust = theAllocator.make!Customer;
assert(cust.id == uint.max); // default initialized
cust = theAllocator.make!Customer(42);
writeln(cust.id); // 42

// explicit passing of outer pointer
static class Outer
{
    int x = 3;
    class Inner
    {
        auto getX() { return x; }
    }
}
auto outer = theAllocator.make!Outer();
auto inner = theAllocator.make!(Outer.Inner)(outer);
writeln(outer.x); // inner.getX

Authors

Andrei Alexandrescu

License

Boost License 1.0.