std::execution::just_error - cppreference.com (original) (raw)
| Defined in header | | | | ------------------------------------------------------------------------------------------- | | ------------------------------------------ | | inline constexpr just_error_t just_error{}; struct just_error_t { /*unspecified*/ }; | | (since C++26) (customization point object) | | Call signature | | | | execution::sender auto just_error( auto&& error ); | | (since C++26) |
A sender factory that returns a sender which completes immediately by calling the receiver’s set_error().
Let e be a subexpression represented by an input error which will be injected and returned by the receiver. The expression just_error(e) is expression-equivalent to /*make-sender*/(just_error, /*product-type*/(e))
Customization point objects
The name execution::just_error denotes a customization point object, which is a const function object of a literal semiregular class type. The cv-unqualified version of its type is a tag type denoted as execution::just_error_t. See CustomizationPointObject for details.
[edit] Notes
If the provided error is an lvalue reference, a copy is made inside the returned sender and a non-const lvalue reference to the copy is sent to the receiver’s set_error. If the provided value is an rvalue reference, it is moved into the returned sender and an rvalue reference to it is sent to the receiver’s set_error.