std::future_errc - cppreference.com (original) (raw)
| | | | | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | ------------- | | enum class future_errc { broken_promise = /* implementation-defined */, future_already_retrieved = /* implementation-defined */, promise_already_satisfied = /* implementation-defined */, no_state = /* implementation-defined */ }; | | (since C++11) |
The scoped enumeration std::future_errc defines the error codes reported by std::future and related classes in std::future_error exception objects. Only four error codes are required, although the implementation may define additional error codes. Because the appropriate specialization of std::is_error_code_enum is provided, values of type std::future_errc are implicitly convertible to std::error_code.
All error codes are distinct and non-zero.
Contents
[edit] Member constants
| Enumerator | Meaning |
|---|---|
| broken_promise | the asynchronous task abandoned its shared state |
| future_already_retrieved | the contents of shared state were already accessed through std::future |
| promise_already_satisfied | attempt to store a value in the shared state twice |
| no_state | attempt to access std::promise or std::future without an associated shared state |
[edit] Non-member functions
[edit] Helper classes
[edit] Example
[edit] Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 2056 | C++11 | broken_promise was specified to be zero which is conventionally used to mean “no error” | specified to be non-zero |