std::execution:: just_error
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Defined in header
<execution>
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||
|
inline
constexpr
just_error_t just_error
{
}
;
struct just_error_t { /*unspecified*/ } ; |
(since C++26)
(customization point object) |
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|
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
.
All instances of
execution::just_error_t
are equal. The effects of invoking different instances of type
execution::just_error_t
on the same arguments are equivalent, regardless of whether the expression denoting the instance is an lvalue or rvalue, and is const-qualified or not (however, a volatile-qualified instance is not required to be invocable). Thus,
execution::just_error
can be copied freely and its copies can be used interchangeably.
Given a set of types
Args...
, if
std::
declval
<
Args
>
(
)
...
meet the requirements for arguments to
execution::just_error
above,
execution::just_error_t
models
- std:: invocable < execution :: just_error_t , Args... > ,
- std:: invocable < const execution :: just_error_t , Args... > ,
- std:: invocable < execution :: just_error_t & , Args... > , and
-
std::
invocable
<
const
execution
::
just_error_t
&
, Args...
>
.
Otherwise, no function call operator of
execution::just_error_t
participates in overload resolution.
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
.
Example
|
This section is incomplete
Reason: no example |