std::experimental::ranges::Writable
Defined in header <experimental/ranges/iterator>
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template
<
class Out, class T >
concept bool Writable =
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(ranges TS) | |
The concept Writable<Out, T> specifies the requirements for writing a value whose type and value category are encoded by T into an iterator Out's referenced object.
Let E be an expression such that decltype((E)) is T, and o be a dereferenceable object of type Out, then Writable<Out, T>
- If
Readable<Out>
&& Same<ranges::
value_type_t
<Out>, std::decay_t
<T>>
is satisfied, then *o after any above assignment is equal to the value of
E
o is not required to be dereferenceable after evaluating any of the assignment expressions above. If E
Equality preservation
An expression is equality preserving if it results in equal outputs given equal inputs.
- The inputs to an expression consist of its operands.
- The outputs of an expression consist of its result and all operands modified by the expression (if any).
Every expression required to be equality preserving is further required to be stable
Notes
The only valid use of operator*
The required expressions with const_cast prevent Readable objects with prvalue reference types from satisfying the syntactic requirements of Writable by accident, while permitting proxy references to continue to work as long as their constness is shallow. See Ranges TS issue 381