是否可以模拟模板< auto X>? [英] Is it possible to emulate template<auto X>?
问题描述
它有可能吗?我想要启用编译时传递参数。假设它仅仅为了用户方便,因为人们总是可以用 template< class T,T X>
来输出真实类型,但是对于一些类型, - 函数,这是非常乏味,即使以 decltype
作为快捷方式。考虑下面的代码:
Is it somehow possible? I want that to enable compile-time passing of arguments. Suppose it's only for user convenience, as one could always type out the real type with template<class T, T X>
, but for some types, i.e. pointer-to-member-functions, it's pretty tedious, even with decltype
as a shortcut. Consider the following code:
struct Foo{
template<class T, T X>
void bar(){
// do something with X, compile-time passed
}
};
struct Baz{
void bang(){
}
};
int main(){
Foo f;
f.bar<int,5>();
f.bar<decltype(&Baz::bang),&Baz::bang>();
}
是否可以将其转换为以下内容?
Would it be somehow possible to convert it to the following?
struct Foo{
template<auto X>
void bar(){
// do something with X, compile-time passed
}
};
struct Baz{
void bang(){
}
};
int main(){
Foo f;
f.bar<5>();
f.bar<&Baz::bang>();
}
推荐答案
在C ++中没有这样的功能。最接近的是宏:
After your update: no. There is no such functionality in C++. The closest is macros:
#define AUTO_ARG(x) decltype(x), x
f.bar<AUTO_ARG(5)>();
f.bar<AUTO_ARG(&Baz::bang)>();
听起来像你想要一个发电机:
Sounds like you want a generator:
template <typename T>
struct foo
{
foo(const T&) {} // do whatever
};
template <typename T>
foo<T> make_foo(const T& x)
{
return foo<T>(x);
}
现在代替拼写:
foo<int>(5);
您可以:
make_foo(5);
推导参数。
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