I have been experimenting with changing the bindings to handle
"static" functions and "enums" that are class members a little more
gracefully.
Example:
class MyClass {
MyClass(...)
int DoStuff(...)
static void StaticMyClassFn(...)
enum {
type1,
type2
}
}
=================
Currently we push these class items into wxLua (assume "wx" table namespace).
wx.MyClass(...) = a cfunction in lua
wx.MyClass_type1 = a number in lua
wx.MyClass_type2 = a number in lua
The function DoStuff is only accessible when you create an object,
"obj = wx.MyClass(...); obj:DoStuff(...)".
The static functions are a little annoying right now and you have to
use the %static, %static_only or just static tag in the binding files.
%static_only gets you wx.MyClass_StaticMyClassFn(...)
static gets you obj = wx.MyClass(...); obj:StaticMyClassFn(...)
(i.e. you must create an object in order to call the function even
though the function doesn't need the object)
%static gets you both
wx.MyClass_StaticMyClassFn(...)
and
obj = wx.MyClass(...); obj:StaticMyClassFn(...)
There are some wxWidgets classes where you cannot get an object of the
class and so we must use the %static_only method, for other classes we
might be temped to always use %static tag, but it really is overkill
to have so many "global" functions in the wx table.
==================
Suggested changes:
A) Make the "classes" pushed into the binding table namespace (e.g.
"wx") a table itself and set the metatable "__call" function to
directly call the constructor function.
B) Or set the metatable of the cfunctions to have __index point to the
enums and static functions.
Both of these two ways, A and B, allow for this calling notation in lua.
wx.MyClass(...) = calls the cfunction in lua
wx.MyClass.type1 = a number in lua
wx.MyClass.type2 = a number in lua
wx.MyClass.StaticMyClassFn(...) = a cfunction in lua
Again, DoStuff() is only accessible to a created object, but now you
can get at the static functions directly and access to them and the
enums are more equivalent to their C++ counterparts.
ISSUES with new methods:
A1) The __call metatable function may take longer to run? (dunno how much)
A2) Since wx.MyClass is of type() = "table" it doesn't properly
register as a function and can't be used as easily as one.
See http://gniemeyer.livejournal.com/tag/c and search for __call for details.
A3) Takes more memory since we have to create two tables, one for the
class and one for the metatable.
B1) Need a metatable table, more memory then original way, but less than A.
B2) Items in the metatable (static functions and enums) are kinda'
"hidden" a little better than they are in A.
You can examine the contents of the wx.wxRect table this way in A
for k, v in pairs(wx.wxRect) do print(k, v) end
In B you have to do this
for k, v in pairs(getmetatable(wx.wxRect).__index) do print(k, v) end
=================
Sorry about the long post, but I'm leaning towards B and wanted some
thoughts on it.
I've committed the code for it here
http://wxlua.cvs.sourceforge.net/wxlua/wxLua/modules/wxlua/src/wxlbind.cpp?revision=1.57&view=markup
see the function wxLuaBinding::RegisterGeneratedClasses and the #if 0
statements. Note that I am not currently pushing the static functions
and enums right now as they would require a change to the binding
generator, so the code is more of a proof of concept.
Regards,
John Labenski
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