blocks|key|3027267|text|No。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|3027268|这在标准库中很明显(它仍然使用显式的const方法)。|CODE|3027269|entityMap^0|0|2|0|I|5|0^^$0|@$1|2|3|4|5|6|7|K|8|@$9|L|A|M|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|N|8|@$9|O|A|P|B|H]]|D|@]|E|$]]|$1|I|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|J|$]]

No. 
It is evident in the Standard Library (it still uses explicit <code>const</code> methods).

blocks|key|5240248|text|我不认为有必要摆脱“不实现2个变体”。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5240249|5240250|如果两个变体做的是不同的东西，那么你必须保持它们的版本，如果两个变体做的是相同的东西，那么删除非常数版本，只维护|ordered-list-item|5240251|5240252|5240253|顺便说一句，如果需要的话，还有第三和第四种变体：|5240254|float_t&+at(+uint32_t+row,+uint32_t+col)+volatile;
float_t&+at(+uint32_t+row,+uint32_t+col)+const+volatile;|code-block|syntax|javascript|5240255|[注:无关，但在C%2B%2B11中，可以使用noexcept关键字添加所有变体，以获取异常相关信息：|offset|length|style|CODE|5240256|float_t&+at(+uint32_t+row,+uint32_t+col)+noexcept;|5240257|]|5240258|entityMap^0|0|0|0|0|0|0|0|J|8|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|11|8|@]|9|@]|A|$]]|$1|C|3|D|5|E|7|12|8|@]|9|@]|A|$]]|$1|F|3|-4|5|E|7|13|8|@]|9|@]|A|$]]|$1|G|3|-4|5|6|7|14|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|15|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|16|8|@]|9|@]|A|$M|N]]|$1|O|3|P|5|6|7|17|8|@$Q|18|R|19|S|T]]|9|@]|A|$]]|$1|U|3|V|5|L|7|1A|8|@]|9|@]|A|$M|N]]|$1|W|3|X|5|6|7|1B|8|@]|9|@]|A|$]]|$1|Y|3|-4|5|6|7|1C|8|@]|9|@]|A|$]]]|Z|$]]

I don't believe there is a need to get rid of "not implementing 2 variants".

<ol>
<li>If both variants are doing different stuff, then you must have to
keep them</li>
<li>If both variants are doing the same stuff, then remove the
non-const version and maintain only the <code>const</code> version</li>
</ol>

By the way, there are 3rd and 4th variants if one ever needs:

<pre><code>float_t&amp; at( uint32_t row, uint32_t col) volatile;
float_t&amp; at( uint32_t row, uint32_t col) const volatile;
</code></pre>

[Note: Irrelevant but in C++11 all the variants can be added with <code>noexcept</code> keyword for exception related info:

<pre><code>float_t&amp; at( uint32_t row, uint32_t col) noexcept;
</code></pre>

]

blocks|key|3511245|text|这在C%2B%2B11中没有改变，但在C%2B%2B17中改变了：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3511246|T+const+&+f()+const+{
++++return+something_complicated();
}
T+&+f()+{
++++return+const_cast<T+&>(std::add_const(*this).f());
}|code-block|syntax|javascript|3511247|请参阅How+do+I+remove+code+duplication+between+similar+const+and+non-const+member+functions?|offset|length|3511248|编辑|style|BOLD|3511249|自从我写了这篇文章以来，我已经改变了我的立场几次。上面的文字反映了我目前的想法。我之前的立场是在两种类型转换中都优先使用const_cast，而我最初的立场是先使用static_cast，然后使用const_cast。const_cast更安全，因为它唯一能做的就是添加/删除const和volatile限定符。static_cast可能会意外地以其他方式强制转换。我最初的想法是更喜欢static_cast而不是添加const，因为它将添加const的最可能的“安全”操作与可能危险的删除const的操作分开。上面代码中的版本具有由std::as_const拼写的安全操作，它只能做我想做的事情，只剩下可能不安全的const_cast作为您唯一需要确保正确完成的操作。|CODE|3511250|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/123758/how-do-i-remove-code-duplication-between-similar-const-and-non-const-member-func^0|0|0|3|2E|0|0|0|2|0|1O|A|2A|B|2Q|A|31|A|3U|5|40|8|4C|B|5D|B|5T|5|65|5|6T|5|7F|D|8K|A|0^^$0|@$1|2|3|4|5|6|7|Z|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|10|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|11|8|@]|9|@$I|12|J|13|1|14]]|A|$]]|$1|K|3|L|5|6|7|15|8|@$I|16|J|17|M|N]]|9|@]|A|$]]|$1|O|3|P|5|6|7|18|8|@$I|19|J|1A|M|Q]|$I|1B|J|1C|M|Q]|$I|1D|J|1E|M|Q]|$I|1F|J|1G|M|Q]|$I|1H|J|1I|M|Q]|$I|1J|J|1K|M|Q]|$I|1L|J|1M|M|Q]|$I|1N|J|1O|M|Q]|$I|1P|J|1Q|M|Q]|$I|1R|J|1S|M|Q]|$I|1T|J|1U|M|Q]|$I|1V|J|1W|M|Q]|$I|1X|J|1Y|M|Q]]|9|@]|A|$]]|$1|R|3|-4|5|6|7|1Z|8|@]|9|@]|A|$]]]|S|$T|$5|U|V|W|A|$X|Y]]]]

This had not changed in C++11, but it has changed in C++17:

<pre><code>T const &amp; f() const {
 return something_complicated();
}
T &amp; f() {
 return const_cast&lt;T &amp;&gt;(std::add_const(*this).f());
}
</code></pre>

See <a href="https://stackoverflow.com/questions/123758/how-do-i-remove-code-duplication-between-similar-const-and-non-const-member-func">How do I remove code duplication between similar const and non-const member functions?</a>

Edit

I have changed my position a few times since making this post. The text above reflects my current thinking. My previous position was to prefer <code>const_cast</code> for both casts, and my original position was <code>static_cast</code> then <code>const_cast</code>. <code>const_cast</code> is safer because the only thing it can do is add / remove <code>const</code> and <code>volatile</code> qualifiers. <code>static_cast</code> can accidentally cast in other ways. My original thinking was to prefer <code>static_cast</code> to add <code>const</code> as it separates the most likely 'safe' operation of adding <code>const</code> from the possibly dangerous operation of removing <code>const</code>. The version in the code above has the safe operation spelled out by <code>std::as_const</code>, which can do only what I want, leaving the potentially unsafe <code>const_cast</code> as the only thing you need to ensure you have done correctly.

Pre C++ 11, I often needed to implement two very-alike variants of a method to deal with const and non-const usage scenarios of the class/struct:

<pre><code>struct my_struct_t{
 ....
 float_t&amp; at( uint32_t row, uint32_t col)
 {
 return *(((float_t*)((uint8_t*)numbers+row*row_stride)) + col);
 }

 float_t const&amp; at( uint32_t row, uint32_t col) const
 {
 return *(((float_t*)((uint8_t*)numbers+row*row_stride)) + col);
 }

};
</code></pre>

Has this changed in C++ 11?

C++ 11x check: how to implement const-variants?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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在C++ 11之前，我经常需要实现两个非常相似的方法变体来处理类/结构的常量和非常量使用场景：struct my_struct_t{     ....     float_t& at( uint32_t row, uint32_t col)     {         return *(((float_t*)((uin...

问C++ 11x检查:如何实现常量变量？
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