首页 \ 问答 \ 使用模板参数作为函数参数(Using template parameters as function parameters)

使用模板参数作为函数参数(Using template parameters as function parameters)

我可以使用函数参数推断模板参数

template <typename T>
void f(T a)
{ /* */ }

f(4); // T inferred to be `int`

但是我不能使用函数参数来推断模板参数,这些参数不是类型:

template <int I>
void g(int I)  // error: declaration of 'I' shadows template parameter
{ /* */ }

假设我想写一个函数divive_dy_2(int number) ,我想确保number不为零。

我已经看到了一种非常简单的方法 ,这需要我将参数传递给模板参数,然后如果它为0则使用SFINAE来禁用它。

但是在API中暴露这样的东西感觉反直觉。 有一些解决方法吗?

(是的,我可以使用例外而不是什么,甚至可能是更好的想法,但我现在正在学习SFINAE,并想知道它的限制在哪里)


I can infer template parameters with function parameters

template <typename T>
void f(T a)
{ /* */ }

f(4); // T inferred to be `int`

However I can't use function parameters to infer template parameters, which aren't types:

template <int I>
void g(int I)  // error: declaration of 'I' shadows template parameter
{ /* */ }

Let's say I want to write a function divive_dy_2(int number) and I want to make sure number is not zero.

I've seen a very simple way to do this, which would require me to pass the argument to a template parameter, which then would use SFINAE to disable it, if it was 0.

But it feels counter-intuitive to expose something like this in an API. Is there some workaround?

(And yes, I could use exceptions and what not, what would probably even be a better idea, but I'm learning SFINAE at the moment and want to know where it's limits are)


原文:https://stackoverflow.com/questions/35870585
更新时间:2022-03-18 18:03

最满意答案

你甚至可能在页面加载之前测试了div id的存在。 我建议您将脚本放在div id之后,或者只在onload事件之后调用该调用。

window.onload=function(){
    // your code
}

you probably tested for the existence of div id before even the page has been loaded. I would suggest you to either place the script after the div id or invoke the call only after the onload event.

window.onload=function(){
    // your code
}

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