C ++为给定列表中的每种类型执行操作 [英] C++ execute an action for each type in a given list

问题描述

我被赋予重构旧代码的费用，偶然发现了这种情况：

I have been given the charge to refactor old code and have stumbled upon this case:

void myClass::doStuff()
{
    for( myIterator< Type1 > it( this->getDatabase() ); it; ++it )
    {
        do1( *it );
        do2( *it );
        do3( *it );
    }
    for( myIterator< Type2 > it( this->getDatabase() ); it; ++it )
    {
        do1( *it );
        do2( *it );
        do3( *it );
    }
    for( myIterator< Type3 > it( this->getDatabase() ); it; ++it )
    {
        do1( *it );
        do2( *it );
        do3( *it );
    }
}

这显然很糟糕，因为我复制了基本相同的代码3因此，我决定使用这样的模板来重构它：

It's obviously bad since I copy basically the same code 3 times so I decided to refactor it using templates like this :

template<class _type> void myClass::do123()
{
    for( myIterator< _type > it( this->getDatabase() ); it; ++it )
    {
        do1( *it );
        do2( *it );
        do3( *it );
    }
}
void myClass::doStuffBetter()
{
    do123<Type1>();
    do123<Type2>();
    do123<Type3>();
}

是否存在其他更容易/更有效的方法来在代码中分解这种重复？

Is there other easier/more productive ways to factorize this kind of repetition in code ?

奖金问题：如果我的类型不是静态的，但在可变参数模板中给出，我将如何做类似的处理？

Bonus question : if my types were not static but given in a variadic template how would I do a similar treatment ?

推荐答案

我发现您的解决方案足够好。

I find your solution good enough.

只是为了好玩，我建议使用以下 doStuffBetter（）

Just for fun, I propose the following doStuffBetter()

template <typename ... Types>
void myClass::doStuffBetter()
 {
   int unused[] { (do123<Types>(), 0)... };

   (void)unused; // to avoid a warning
 }

应该与C ++ 11一起工作，我想也可以回答您的奖金问题。

Should work with C++11 and I suppose that can respond to your bonus question too.

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