# std::experimental::unique_resource

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< cpp‎ | experimental

Defined in header `<experimental/scope>` |  |
template< class R, class D > class unique_resource; |  | (library fundamentals TS v3)

`unique_resource` is universal RAII wrapper for resource handles that owns and manages a resource through a handle and disposes of that resource when the `unique_resource` is destroyed.

The resource is disposed of using the deleter of type `D` when either of the following happens:

- the managing `unique_resource` object is destroyed,
- the managing `unique_resource` object is assigned from another resource via operator= or reset().

Let type `RS` be `R` if `R` is an object type, or std::reference_wrapper < std::remove_reference_t <R>> otherwise:

- `unique_resource` effectively holds a subobject of type `RS` which is or wraps the resource handle, a deleter of type `D` and a bool flag indicating whether the wrapper is owning the resource.
- For explanatory purpose, the subobject of type `RS` is called stored resource handle, and the stored (if `R` is an object type) or wrapped (if `R` is a reference type) `R` is called underlying resource handle. These two terms are not used by the LFTS.

### Template parameters

R | - | resource handle type
D | - | deleter type
Type requirements
- `R` shall be an object type or an lvalue reference to an object type. Let `UnrefR` be std::remove_reference_t <R>, `UnrefR` shall be MoveConstructible, and if `UnrefR` is not CopyConstructible, std::is_nothrow_move_constructible_v <UnrefR> shall be true.
- `D` shall be a Destructible and MoveConstructible FunctionObject type, and if `D` is not CopyConstructible, std::is_nothrow_move_constructible_v <D> shall be true. Given an lvalue `d` of type `D` and an lvalue `r` of type `UnrefR`, the expression d(r) shall be well-formed.

### Member functions

(constructor) | constructs a new `unique_resource` (public member function)
(destructor) | disposes the managed resource if such is present (public member function)
operator= | assigns a `unique_resource` (public member function)

##### Modifiers

release | releases the ownership (public member function)
reset | disposes or replaces the managed resource (public member function)

##### Observers

get | accesses the underlying resource handle (public member function)
get_deleter | accesses the deleter used for disposing of the managed resource (public member function)
operator*operator-> | accesses the pointee if the resource handle is a pointer (public member function)

### Non-member functions

make_unique_resource_checked | creates a `unique_resource`, checking invalid value (function template)

### Deduction guides

### Notes

Resource handle types satisfying NullablePointer can also be managed by std::unique_ptr. Unlike `unique_ptr`, `unique_resource` does not require NullablePointer.

### Example

| This section is incomplete Reason: no example

### See also

unique_ptr (C++11) | smart pointer with unique object ownership semantics (class template)

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