C++核心準則Enum.2: 使用枚舉表現(xiàn)一組相關(guān)的命名常量

Enum.2: Use enumerations to represent sets of related named constants

Enum.2: 使用枚舉表現(xiàn)一組相關(guān)的命名常量

Reason(原因)

An enumeration shows the enumerators to be related and can be a named type.

枚舉類型表示枚舉值之間具有相關(guān)性，并且可以成為命名類型。

Example(示例)

enum class Web_color { red = 0xFF0000, green = 0x00FF00, blue = 0x0000FF };

Note(注意)

Switching on an enumeration is common and the compiler can warn against unusual patterns of case labels. For example:

啟用枚舉類型屬于常規(guī)操作，并且編譯器可以對不平常的用法進行警示。例如：

enum class Product_info { red = 0, purple = 1, blue = 2 };

void print(Product_info inf)
{
    switch (inf) {
    case Product_info::red: cout << "red"; break;
    case Product_info::purple: cout << "purple"; break;
    }
}

Such off-by-one?switch-statements are often the results of an added enumerator and insufficient testing.

這種"只越界一點"的switch語句通常是增加枚舉值后沒有充分測試的結(jié)果。

Enforcement(實施建議)

• Flag?switch-statements where the?cases cover most but not all enumerators of an enumeration.

• 提示switch語句覆蓋大多數(shù)枚舉值卻沒有覆蓋所有枚舉值的情況。
  

• Flag?switch-statements where the?cases cover a few enumerators of an enumeration, but has no?default.

• 提示swtich語句覆蓋了少數(shù)枚舉值卻沒有default分支的情況。
  

原文鏈接：

https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#enum2-use-enumerations-to-represent-sets-of-related-named-constants

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