Hello all,
I'm new to Lua, but I think that it is an excellent scripting language
and would like to use it in combination with C++. I've read a good
deal of http://www.lua.org/pil/ , especially "Part IV. The C API", but
apparently due to my lack of experience with Lua, I've not been able
to my problem myself.
The problem is that I have a simple hierarchy (a tree) of C++ objects,
as for example windows that can be found in a GUI system:
(For clarity, I'm just providing pseudo-code, it will probably not
compile.)
class Window
{
public:
Window* Find(char* n); // Find a window with name "n" in the
hierarchy tree of this window.
void Draw(); // Draws this window on the screen -
implemented in C++.
void SomeMethod(float f); // Some helper method for demonstration
purposes, also implem. in C++.
void OnMouseClick(); // Some event handler - supposed to be
implemented by a Lua script!
std::string name; // Name of this window, e.g. for
reference in Lua scripts.
int pos[2]; // The position of the top-left corner
of this window.
int size[2]; // The size of this window in pixels.
float back_col[3]; // The background color.
float text_col[3]; // The text / foreground color.
std::string text; // Text to be displayed in the window.
Window* parent; // The parent of this window (may be NULL).
vector<Window*> children; // The sub-windows of this window (e.g.
the buttons in a dialog).
};
As mentioned in the comments, I'd like to use Lua to implement the
OnMouseClick() method of each Window, so that each Window has an
individual implementation if desired.
Here is an example for an implementation of the OnMouseClick() method
as I'd write it in C++:
void Window::OnMouseClick()
{
// The contents of this method is supposed to
// be implemented with a Lua script...
back_col[0]=0.0f;
back_col[1]=0.3f;
back_col[2]=0.9f;
SomeMethod(0.2f);
size[0]=100.0f;
size[1]=20.0f;
text="I was clicked!";
WindowT* other=Find("Button OK");
other->SomeMethod(3.0f);
other->pos[0]=80.0f;
other->text="OK";
parent->text="My parent too...";
// and so on...
}
So in spite of having read the PIL book, I have not the faintest idea
what the best approach to this problem is:
I might be able to model a table hierachy in Lua that mirrors the
Window hierachy in C++, but what then?
Don't I have to manually "synchronize" both hierarchies after each
call from/to Lua/C++??
Should I use userdata instead, analogous to
http://www.lua.org/pil/28.1.html?
Are there any C++ specific examples where I can learn how this problem
should be approached?
