std::execution:: just

A sender factory that returns a sender which completes immediately by calling the receiver’s set_value() .

Let ts be a pack of subexpressions. The expression just ( ts... ) is expression-equivalent to /*make-sender*/ ( just, /*product-type*/ ( ts... ) )

Customization point objects

The name execution::just 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_t .

All instances of execution::just_t are equal. The effects of invoking different instances of type execution::just_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 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 above, execution::just_t models

• std:: invocable < execution :: just_t , Args... > ,
• std:: invocable < const execution :: just_t , Args... > ,
• std:: invocable < execution :: just_t & , Args... > , and
• std:: invocable < const execution :: just_t & , Args... > .
  

Otherwise, no function call operator of execution::just_t participates in overload resolution.

Example