具有重复的枚举值

发布于 2024-12-16 17:41:30 字数 398 浏览 2 评论 0原文

我正在用 C++ 创建一个俄罗斯方块克隆，并且有一个枚举 GameProperty，其指定如下：

enum GameProperty {
    NUM_OF_TETROMINOES  = 7,
    NUM_OF_TILES        = 4,
    TETROMINO_ROTATIONS = 4
};

在我的例子中，我仅在循环访问时使用这些值。 tetromino 的图块，例如：

for (int i = 0; i < TETROMINO_TILES; i++) { }

在任何情况下，拥有多个具有相同值的枚举器是否被认为是不好的做法？

原文

I'm creating a Tetris clone in C++, and I have an enum GameProperty, which is specified as follows:

enum GameProperty {
    NUM_OF_TETROMINOES  = 7,
    NUM_OF_TILES        = 4,
    TETROMINO_ROTATIONS = 4
};

In my case, I only use these values when looping through a tetromino's tiles, e.g:

for (int i = 0; i < TETROMINO_TILES; i++) { }

Is it under any circumstance considered bad practice to have multiple enumerators with the same value?

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用心笑 2024-12-23 17:41:30

这些不应该是单个枚举中的值。它们应该是单独的常量。要了解原因，请查看类似 i <; 的代码。 TETROMINO_TILES。它将integer 与GameProperty 进行比较，后者可以具有诸如TETROMINO_ROTATIONS 之类的值。这毫无意义。

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稀香 2024-12-23 17:41:30

当您想要创建一个新的、不同的类型，而该类型实际上不是一个标量值时，请使用enum。例如，颜色可以被枚举，因此可以编号，但这些数字实际上没有任何意义。

如果您为枚举器分配有意义的数字，则表明您可能确实想要这样的东西：

namespace GameProperty { // completely different concepts with unifying theme
    int const num_tetrominoes  = 7,
              num_tiles        = 4,
              num_rotations    = 4;
};

现在您可以使用相同的语法以及 using 声明，并且这些常量可以在 < code>for 循环和表达式，无需转换。

再举一个例子，以下内容都是正确的，但不应在 enum 和 int 之间交换：

namespace wavelengths { // closely related quantities
    typedef int wavelength_t; // maybe we will express in-between values
    wavelength_t const red    = 750,
                       green  = 550,
                       blue   = 400;
};

enum colors { // qualitatively different but related as one-of-many
    red,
    green,
    blue;
};

Use enum when you want to create a new, distinct type which isn't really a scalar value. For example, colors can be enumerated, and hence numbered, but those numbers don't really mean anything.

If you're assigning meaningful numbers to the enumerators, it's a sign that you might really want something like this:

namespace GameProperty { // completely different concepts with unifying theme
    int const num_tetrominoes  = 7,
              num_tiles        = 4,
              num_rotations    = 4;
};

Now you can use the same syntax, as well as using declarations, and these constants work in for loops and expressions with no conversion.

For another example, the following are both correct but shouldn't be swapped between enum and int:

namespace wavelengths { // closely related quantities
    typedef int wavelength_t; // maybe we will express in-between values
    wavelength_t const red    = 750,
                       green  = 550,
                       blue   = 400;
};

enum colors { // qualitatively different but related as one-of-many
    red,
    green,
    blue;
};

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