You have to specify a type for the inner class
Nested<int>::Inner<char> inner(43);
and add some code to your destructor
virtual ~Nested() {}
Domanda
I have template class with inner class
template<class param>
class Nested {
param obj;
public:
template<class X>
class Inner {
X obj;
public:
Inner(X obj) : obj(obj) {}
X getObj() { return obj; }
};
Nested();
Nested(param obj) : obj(obj) {}
param getObj() { return obj; }
virtual ~Nested();
};
I try:
Nested<int>::Inner<int> inner(43);
but i get compilation error:
C++/TemplateClass/Debug/../src/TemplateClass.cpp:20: undefined reference to `Nested<int>::~Nested()'
C++/TemplateClass/Debug/../src/TemplateClass.cpp:20: undefined reference to `Nested<int>::~Nested()'
and next posiblities:
Nested<int>::Inner inner(43);
../src/TemplateClass.cpp: In function ‘int main()’:
../src/TemplateClass.cpp:17:24: error: invalid use of template-name ‘Nested<int>::Inner’ without an argument list
typename Nested<int>::Inner inner(43);
^
../src/TemplateClass.cpp:17:35: error: invalid type in declaration before ‘(’ token
typename Nested<int>::Inner inner(43);
^
../src/TemplateClass.cpp:18:42: error: request for member ‘getObj’ in ‘inner’, which is of non-class type ‘int’
cout << "Inner param object: " << inner.getObj() << endl;
How can I create Inner class object?
Soluzione
You have to specify a type for the inner class
Nested<int>::Inner<char> inner(43);
and add some code to your destructor
virtual ~Nested() {}
Altri suggerimenti
I tried this on http://www.compileonline.com/compile_cpp11_online.php
It works as intended. For this narrow example you don't need to define a destructor for Nested<> because a Nested<> instance is not created.
#include <iostream>
template<class param>
class Nested {
param obj;
public:
template<class X>
class Inner {
X obj;
public:
Inner(X obj) : obj(obj) {}
X getObj() { return obj; }
};
Nested();
Nested(param obj) : obj(obj) {}
param getObj() { return obj; }
virtual ~Nested();
};
int main()
{
Nested<int>::Inner<int> temp(43);
std::cout << temp.getObj() << std::endl;
return 0;
}