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- Subject: class binding question
- From: "W. Scott Dillman" <sdillman@...>
- Date: Thu, 26 Feb 2004 09:06:42 -0600
I have a pretty noob question but I have several ways to solve my problem and I think I just
need a nudge in the right direction.
I found Virgil Smith's post here: http://lua-users.org/lists/lua-l/2003-12/msg00483.html
That describes in detail what I am trying to do, but I must be missing something.
Here is what I am trying to do ( pretty common ), I know I can use all the binding libraries
and add-ons out there, but I prefer to write my own.
Lets say I have a C++ class like the following:
class A
{
public:
A() : iSomeVal(0){}
int iSomeVal;
int doSomething(int i);
}
And I want to be able to do this in lua:
A("myA");
myA.iSomeVal = 10;
local x = myA.iSomeVal;
myA:doSomething(x);
I can get pieces of the above to work, but I am missing something somewhere.
If I use a method table to register my object and methods, something like this:
lua_pushliteral(L, "__index");
lua_pushvalue(L, methodtable);
lua_settable(L, metatable);
Where methodtable is a table filled with cfunctions and upvalues something like:
myA:doSomething(x)
works great, but I am at a loss at how to implement the reading of member data
because something like:
local x = myA.iSomeVal;
returns whatever is in the table field, so if I store it as a fuction; x now holds a function
reference, so I'm unsure how to implement it. Of course if I call:
local x = myA.iSomeVal();
It works, but is messy.
If I take the other route and do something like:
lua_pushliteral(L, "__index");
lua_pushcfunction(L, &myGetter);
lua_settable(L, metatable);
And do my decision making about function or member in the 'myGetter' function, it works
well but lua throws an error after the execution of the statement, if I call a function
complaining of a nil value, even though it executes fine.
Any advice would be great...
Thanks,
Scott