Enum.4:为枚举类型定义运算符以便安全又简单地使用
Convenience of use and avoidance of errors.
方便使用又少犯错。
Example(示例)
enum Day { mon, tue, wed, thu, fri, sat, sun };
Day& operator++(Day& d)
{
return d = (d == Day::sun) ? Day::mon : static_cast<Day>(static_cast<int>(d)+1);
}
Day today = Day::sat;
Day tomorrow = ++today;
The use of a static_cast is not pretty, but
static_cast的用法不太好,但是:
Day& operator++(Day& d)
{
return d = (d == Day::sun) ? Day::mon : Day{++d}; // error
}
is an infinite recursion, and writing it without a cast, using a switch on all cases is long-winded.
是一个特别深的递归,如果不用cast,使用覆盖所有情况的switch语句又会过于繁杂。
Enforcement(实施建议)
Flag repeated expressions cast back into an enumeration.
标记反复转换,最后变成枚举类型的表达式。
原文链接:
https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#enum4-define-operations-on-enumerations-for-safe-and-simple-use
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