c++ template problem

Question

i have a class which has a template by other purposes:

template
class MyClass {
    public: //of course public...
    t foo;
    std::string text;         


        

Answer 1

The simplest method would be to make that function a template as well:

template <class t>
void bar(MyClass<t>& m) {
    // ...
}

Note that that should probably be const MyClass<t>&, because you don't need to modify it.

---

Your new code is meaningless. There is no such that as an object of type MyClass, because MyClass is a template. If you want to operate on these classes irrespective of their template argument, then you need to factor out the non-template portions as a base class:

class MyClassBase
{
public:
    // polymorphic base classes should always have virtual destructors
    ~MyClassBase() {}

    virtual void some_function() = 0;
};

template <typename T>
class MyClass : public MyClassBase
{
public:
    // implement abstract functions
    void some_function()
    {
        // template argument T is available here
    }
};

Then you can refer to that base, and when you call a virtual function it will dynamically dispatch:

class Container
{
public:
    // no magic: use a std::vector for dynamic arrays
    std::vector<MyClassBase*> array; // not by value! avoid slicing

    void bar(MyClassBase& m)
    {
        array.push_back(&m);
    }

    void baz()
    {
        array[0]->some_function(); // for example
    }
};

Answer 2

the text variable in your class is private so unless you bar function is a method of the class you can't legally use it like that

Answer 3

How about putting a common base class.

class MyClassCommon {
protected:
    ~MyClassCommon() { }

public:
    std::string text;
};

template<class t>
class MyClass : public MyClassCommon {
public: // of course public...
    t foo;
};

class Container {
public: // of course public...
    MyClassCommon* array; // this is allocated with some magic.
    void bar(MyClassCommon& m) {
        /* ... */
    }
};

Answer 4

If you want to create a "multi-template" array, you'd better use a non-template class as a base class of a template class. Or you can make a template array and store any objects in it.