使用静态成员函数替换静态const成员的优点[重复](Advantage of replacing static const members with static member functions

使用静态成员函数替换静态const成员的优点[重复](Advantage of replacing static const members with static member functions [duplicate])

这个问题在这里已有答案：

static constexpr变量vs函数 1回答

我从程序员那里得到了这样的代码，我非常尊重：

class BigClass { using MyId = uint32_t; static constexpr MyId INVALID_ID() { return std::numeric_limits<MyId>::max();}; class SmallClass { /* Constructor, etc. */ MyId id = INVALID_ID(); /* Default value */ }; };

将INVALID_ID（）定义为函数而不是静态const变量有明显的优势吗？

静态constexpr变量vs函数的问题与我的问题完全相同（我使用uint32_t作为示例，但我发现其他类型的问题也很有趣）。 但是，我对这个问题的答案不满意。 在阅读了这里的一些答案后，我相信使用函数比使用简单模板的能力更有优势。

This question already has an answer here:

static constexpr variable vs function 1 answer

I came across code like this from a programmer I highly respect:

class BigClass { using MyId = uint32_t; static constexpr MyId INVALID_ID() { return std::numeric_limits<MyId>::max();}; class SmallClass { /* Constructor, etc. */ MyId id = INVALID_ID(); /* Default value */ }; };

Is there any obvious advantage to defining INVALID_ID() as a function instead of as a static const variable?

The question static constexpr variable vs function is precisely the same question I had (I used uint32_t as an example, but I find the question interesting for other types as well). However, I am not satisfied with the answer to that question. After reading some of the answers here, I believe there are more advantages to using functions than the ability to be easily templated.

最满意答案

一个原因是在这种形式中，不需要在类外定义静态成员，这在类在头部内实现的情况下是不合需要的。

第二个原因是可扩展性，您可能有一天希望您的无效ID在其初始化中执行其他constexpr逻辑，而不是调用一个constexpr函数，如max

One reason is that in this form, there is no need for defining the static member outside the class, which in cases where the class is implemented inside a header can be undesirable.

A second reason is extensibility, you could one day want your invalid ID to do some other constexpr logic in its initialization, other than calling one constexpr function like max