| Defined in header <future> | ||
|---|---|---|
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. | (since C++14) |
Member constants
| Constant | Explanation |
|---|---|
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 |
Non-member functions
| constructs a future error code (function) | |
| constructs a future error_condition (function) |
Helper classes
extends the type trait std::is_error_code_enum to identify future error codes (class template) |
Notes
In C++11, broken_promise was specified to equal zero despite std::error_code/std::error_condition using zero to mean "no error". This was fixed in C++14.
Example
See also
| (C++11) | holds a platform-dependent error code (class) |
| (C++11) | holds a portable error code (class) |
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