default typedefs initlisation

[Abhishek Saksena]

Does anybody know how I can achieve the following

I have different flavors of base class :-
========================
class base //empty class
{

};

class base //base class with x_type defination
{
public:
typedef int x_type;
}

class base //base class with y_type defination
{
public:
typedef int y_ype;
}

class base //base class with x_type and y_type defination
{
public:
typedef int x_type;
typedef int y_ype;
}
==========================

now I want to use one of these base class as a template parameter to some
other class. Something like

template<typaname T>
class xyz
{
typedef typename T::x_type x_type;
typedef typename T::y_type y_type;
};

The issue is that if the both or one of the types not defined in the base
class then I would like to initialize the x_type and y_type (defined in
class xyz) to some default type like bool.(without generating the
compile-time error)


Abhishek

 

[Me]

The issue is that if the both or one of the types not defined in the base

class then I would like to initialize the x_type and y_type (defined in
class xyz) to some default type like bool.(without generating the
compile-time error)

http://www.boost.org/libs/utility/enable_if.html