Proplems understanding C++ templates.

Jeroi

I have problems understanding C++ templates. I have read that templates are for unknown types and c++ have more features than C# and since I am doing converting code I have troubles to understand whats wrong here is:

@template<typename T>
class IDable : public IIDable
{
public:
T Data;

IDable(const QString &id, T t)
{
this->id = id;
this->Data = t;
}

private:
QString id;
const QString &getID() = IIDable->ID->get const
{
return id;
}

};

//C# TO C++ CONVERTER TODO TASK: There is no native C++ template equivalent to generic constraints:
template<typename TType> where TType : IIDable@

The error message from converter sofware tells something but it is not clear issue for me as I have never used templates. How to modify this code to C++ eqvalient?

koahnig

This is hardly a Qt issue.

From a C++ template view neither line 15 nor line 23 make sense.

@
template<typename T>
class IDable : public IIDable
{
public:
T Data;

IDable(const QString &id, T t)
{
this->id = id;
this->Data = t;
}

private:
QString id;

const QString &getID() const
{
    return id;
}

};

//C# TO C++ CONVERTER TODO TASK: There is no native C++ template equivalent to generic constraints:
// template<typename TType> where TType : IIDable
@

So you should be able to compile, but most likely some functionality is missing.

Jeroi

Is this quick and dirty fix for this:

@template<typename TType> class GenericRegisterer { private: GenericRegisterer(){}};
template<> class GenericRegisterer<IIDable> { public: GenericRegisterer(){}};@

Jeroi

It is not because TType is not defined for next class so GenerigRegister don't know variable TType.

JohanSolo

//C# TO C++ CONVERTER TODO TASK: There is no native C++ template equivalent to generic constraints:
template<typename TType> where TType : IIDable

What is that line supposed to achieve?

It is not because TType is not defined for next class so GenerigRegister don't know variable TType.

Definitely not. The template< typename XX > syntax is used to tell the compiler to "build" a method / class as soon as you are using the method / class with a defined type (int, custom class, etc.). The keyword placed after typename will just be replaced by the used type at compile time and does not mean anything.