[英]Correct syntax for separate definition of templated nested class methods
I'm writing a class that requires an additional nested class within, on top of being a template to allow different numeric types: 我正在编写一个类,该类除了作为允许不同数字类型的模板外,还需要其他嵌套类:
template<typename _type>
class myClass{
// ...
class myNestedClass{
myNestedClass(int v1, int v2);
myNestedClass& operator= (std::vector<int> _vals);
operator std::vector<_type>() const;
// ...
}
// ...
template <typename _input_type> operator*= (_input_type _val);
// ...
}
I've got most of the syntax down, particularly how to define the methods after class definition: 我已经掌握了大部分语法,尤其是在类定义之后如何定义方法:
template <typename _type>
template <typename _input_type>
myClass<_type>& myClass<_type>::operator*=(_input_type _val){ /* */ };
but I'm not being able to follow the same scheme for the nested class methods: 但是我无法对嵌套类方法采用相同的方案:
template <typename _type>
myClass<_type>::myNestedClass::myNestedClass(int v1, int v2) { /* */ };
template <typename _type>
myClass<_type>::myNestedClass&
template <typename _type> myClass<_type>::myNestedClass::operator= (std::vector<int> _vals) { /* */ }
template <typename _type>
myClass<_type>::myNestedClass::operator std::vector<_type> () const { /**/ };
But the compiler complains about the last two method definitions, with error: need 'typename' before 'myClass<_type>::myNestedClass' because 'myClass<_type>' is a dependent scope
但是编译器抱怨最后两个方法定义,但有
error: need 'typename' before 'myClass<_type>::myNestedClass' because 'myClass<_type>' is a dependent scope
So what exactly am I writing wrong here? 那么我在这里写错了什么呢?
See When is the "typename" keyword necessary? 请参阅何时需要“ typename”关键字? .
。
You were very close, anyway. 无论如何,你都非常亲密。 After fixing it (plus a few typos around):
修复后(加上一些错别字):
template<typename _type>
class myClass{
// ...
class myNestedClass{
myNestedClass(int v1, int v2);
myNestedClass& operator= (std::vector<int> _vals);
operator std::vector<_type>() const;
// ...
};
// ...
template <typename _input_type> myClass<_type>& operator*= (_input_type _val);
// ...
};
template <typename _type>
template <typename _input_type>
myClass<_type>& myClass<_type>::operator*=(_input_type _val){ /* */ }
template <typename _type>
myClass<_type>::myNestedClass::myNestedClass(int v1, int v2) { /* */ }
template <typename _type>
typename myClass<_type>::myNestedClass& myClass<_type>::myNestedClass::operator= (std::vector<int> _vals) { /* */ }
template <typename _type>
myClass<_type>::myNestedClass::operator std::vector<_type> () const { /**/ }
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