多继承情况下的构造函数

Question

this may be a stupid question but I'm dealingthe first time with multi-inheritance.

Single-inheritance is defined and works like this:

class Canvas3D : public CanvasBase
{
...

Here Canvas3D inherits from CanvasBase and therefore the base-constructor has to be called this way on construction:

Canvas3D::Canvas3D(window* parent)
         :CanvasBase(parent)
{
...

Now Canvas3D needs to inherit from two base classes:

class Canvas3D : public CanvasBase, public GLCanvas
{
...

How do I call the base-constructor of GLCanvas when it does not provide a default constructor? These variants do not work:

Canvas3D::Canvas3D(window* parent)
         :CanvasBase(parent)
         ,GlCanvas(parent)
{
...

Canvas3D::Canvas3D(window* parent)
         :CanvasBase(parent)
         :GlCanvas(parent)
{
...

Answer 1

The Canvas3D constructor needs to take in the parameters to construct the GLCanvas part and pass them to the GLCanvas constructor.

Canvas3D::Canvas3D(window* parent, GLCanvas_Parameters) : 
    CanvasBase(parent), GlCanvas(GLCanvas_Parameters)
{
    //...
}