vector and nested classes

[pmzf]

Hi,

I am using <vector> with an interface like,

vector<interface*> b;


and then filling the container as follows,

b.push_back(new derived_class(x,y);

Both of these work fine, however, i am then trying to use part of a nested class, such as,

b.push_back(new X::Y(i,j));

This doesn't compile. I am at a loss as how to get round this problem. Any advice would be awesome.

Cheers

(Also apologies for any miss-use of terminology. Still new to programming and this is my first attempt at using the stl)

[m4ster r0shi]

Is the nested class (Y) derived from interface too? Is it declared in the global scope of the class containing it (X)? What compilation errors do you get exactly?

[pmzf]

namespace N
{

class interface
{public:
    pure virtual functions
};

class X: public interface
{
    public:
         class Y
         {
           stuff related to Y
         };

         another nested class
        {
        };

};

class derived_class:public shape
{
};

};

The error i get is;

error C2664: 'std::vector<_Ty>::push_back' : cannot convert parameter 1 from 'N::X::Y *' to 'N::X *const &'

with
[
_Ty= N :: interface*
]

Reason: cannot convert from 'N::X::Y *' to 'N::interface *const '

Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast

[m4ster r0shi]

As you can see, class Y isn't derived from interface. I think this is the cause of the problem. Try defining class Y like this:

class X: public interface
{
    public:
         class Y: public interface //<-add this here!
         {
           //stuff related to Y
         };

     //...
};

But if it doesn't make sense that Y should be derived from interface then don't do it... Find another way to solve it, redesigning your inter-class relationships. Why do you need the nested classes anyway? What are you trying to do?

[pmzf]

Hi, Sorry for late reply, have been without internet for a few days but didn't want to appear rude. I changed the structure of my code so everthing works as intended now.

Thanks for your help