You should say this->getSize
or C::getSize
; this will defer lookup to the second phase when the template arguments are known.
Call object's method within template
-
03-07-2022 - |
Pergunta
I have following code:
template<class T>
class TemplateA : public virtual std::list<T>
{
protected:
unsigned int iSize;
public:
unsigned int getSize();
};
/////////////
template<class T>
unsigned int TemplateA<T>::getSize()
{
return iSize;
}
/////////////
/////////////
/////////////
template<class T>
class TemplateB : public TemplateA<T>
{
public:
unsigned int calcSize();
};
/////////////
template<class C>
unsigned int TemplateB<C>::calcSize()
{
iSize = C.getSize;
return iSize;
}
/////////////
/////////////
/////////////
// Class C (seperate file) has to contain function getSize()
class CMyClass
{
public:
static const unsigned int getSize = 5;
};
This means, within class TemplateB I want to call the getSize method, which the passed class have defined.
I receive the following error message:
error C2275: 'C' : illegal use of this type as an expression
while compiling class template member function 'unsigned int TemplateB<C>::calcSize()'
1> with
1> [
1> C=CMyClass
1> ]
I'm quiet sure that this function worked under VS 2003... What's wrong with the method? Maybe a compiler setting? I don't know where to set what :(
Solução
Outras dicas
Hi you could simplify your code too whilst correcting, all you seem to have done is use C rather than TemplateB so if you do:
template<class C>
unsigned int TemplateB<C>::calcSize()
{
return c::getSize; //based on getSize being static
}
You will save the memory of an extra variable and it should work fine:)
Addendum: Here is a working code snippet using your code as a basis:
#include <iostream>
#include <list>
using namespace std;
template<class T>
class TemplateA : public virtual std::list<T>
{
protected:
unsigned int iSize;
public:
unsigned int getSize();
};
template<class T>
unsigned int TemplateA<T>::getSize()
{
return iSize;
}
template<class T>
class TemplateB : public TemplateA<T>
{
public:
unsigned int calcSize();
};
template<class C>
unsigned int TemplateB<C>::calcSize()
{
return C::getSize;
}
// Class C (seperate file) has to contain function getSize()
class CMyClass
{
public:
static const unsigned int getSize = 5;
};
int main()
{
CMyClass classme;
TemplateB<CMyClass> test ;
cout <<"Calc size outputs: "<< test.calcSize() << endl;
return 0;
}
Apologies for the unchecked answer previously. Hope this one helps!
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