std::experimental::not_fn

 

C++

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Technical Specifications

 

Technical specifications

Filesystem library (filesystem TS)

Library fundamentals (library fundamentals TS)

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Extensions for concurrency (concurrency TS)

 

Library fundamentals v2

experimental::propagate_const

experimental::not_fn

experimental::observer_ptr

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detection idiom

uniform container erasure

 

Defined in header <experimental/functional>
template< class F> /*unspecified*/ not_fn( F&& f );		(library fundamentals TS v2)

Creates a forwarding call wrapper that returns the complement of the callable object it holds.

Parameters

f

-

the object from which the Callable object held by the wrapper is constructed

Return value

Let FD be std::decay_t<F> and fd be an lvalue of type FD constructed from std::forward<F>(f).

not_fn returns a forwarding call wrapper fn of unspecified type such that fn(a1, a2, ..., aN) is equivalent to !INVOKE(fd, a1, ..., aN), where INVOKE is the operation described in Callable.

The returned call wrapper is always MoveConstructible, and is CopyConstructible if FD is CopyConstructible.

Remarks

If fd is not Callable, or std::is_constructible<FD, F>::value is not true, the behavior is undefined.

Exceptions

Throws no exceptions, unless the construction of fd throws.

Notes

not_fn is intended to replace the C++03-era negators std::not1 and std::not2.

See also

unary_negate	wrapper function object returning the complement of the unary predicate it holds (class template)
binary_negate	wrapper function object returning the complement of the binary predicate it holds (class template)
not1	constructs custom std::unary_negate object (function template)
not2	constructs custom std::binary_negate object (function template)