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tt(Error_condition)hi(error_condition) objects contain information about
`higher level' types of errors. They are supposed to be platform independent
like syntax errors or non-existing requests.
Error condition objects are returned by the member tt(default_error_condition)
of the classes tt(error_code) and tt(error_category), and they are returned by
the function hi(make_error_condition)tt(std::error_condition
make_error_condition(ErrorConditionEnum ec)). The type name
tt(ErrorConditionEnum) is a formal name for an tt(enum class) that enumerates
the `higher level' error types. The tt(error_condition) objects returned by
tt(make_error_condition) are initialized with tt(ec) and the
tt(error_category) that uses the tt(ErrorConditionEnum). Defining your own
tt(ErrorConditionEnum) is covered in section ref(ERRCODEENUM).
bf(Constructors):
itemization(
ittq(error_condition() noexcept)
(the object's value is initialized to `no error' (i.e., 0) and
a tt(system_category) error category;)
it() The copy constructor is available;
ittq(error_condition(int ec, error_category const &cat) noexcept)
(the object's value is initialized to tt(ec) and error category
tt(cat). It is the responsibility of the caller to ensure that tt(ec)
represents a (cast to tt(int)) value of tt(cat's) error condition
enumeration;)
ittq(error_condition(ErrorConditionEnum value) noexcept)
(this is a member template (cf. section ref(MEMTEMP)), using template
header tt(template <class ErrorConditionEnum>). It initializes the
object with the return value of
tt(make_error_condition(value));)
)
bf(Members):
itemization(
it() The copy assignment operator and an assignment operator accepting an
tt(ErrorConditionEnum) are available;
ittq(void assign(int val, error_category const &cat))
(assigns new values to the current object's em(value) and
em(category) data members;)
ittq(error_category const &category() const noexcept)
(returns a reference to the object's error category (note that this is
a reference to the category's singleton object);)
ittq(void clear() noexcept)
(after calling this member em(value) is set to 0 and the object's error
em(category) set to tt(generic_category);)
ittq(string message() const)
(returns tt(category().message(value()));)
ittq(explicit operator bool() const noexcept)
(returns tt(true) if tt(value()) returns a non-zero value (so its
semantic meaning is `the object represents an error');)
ittq(int value() const noexcept)
(returns the object's error value.)
)
Two tt(error_condition) objects can be compared for (in)equality, and can be
ordered using tt(operator<). Ordering is pointless if the two objects refer to
different error categories. If the categories of two objects are different
they are considered different.
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