Re: self

[Graham Wakefield <lists@...>]

Ah, of course. So the complete example:

function method(o, func)
	return function(...)
		setfenv(func, o)	-- this has to go inside the returned function
		return func(...)
	end
end

-- example --

obj = { foo = 4 }
test = function()
	foo = foo + 1 	-- no self or upvalue
end

obj.fooIncr = method(obj, test)
obj.fooIncr()
print(obj.foo) -- 5


NB a different approach that doesn't work:

function method(o, func)
	local f = function(...)
		return func(...)
	end
	setfenv(f, o)
	return f
end

Because the setfenv(f, o) doesn't cascade to the func(), because func  
itself has not been copied, just wrapped.  What I really wanted was  
to duplicate func() completely, and change its environment  
immediately after, rather than change the environment of the unique  
func method on each call.  I wonder if it makes much difference for  
performance.

On Mar 15, 2007, at 3:22 PM, Miles Bader wrote:

> Graham Wakefield <lists@grahamwakefield.net> writes:
> > Except that I can't figure out how to make a copy of a function  
> > in  Lua
> > (or in the Lua API).  I guess I need to create a new closure,   
> > which I
> > can do with a cfuntion, but I can't see how to do it with a  lua
> > function.
>
>    function copy_fun (fun)
>      return function(...) return fun(...) end
>    end
>
> ?
>
> [The extra level of indirection is ever so slightly annoying, but ...]
>
> -miles
> --
> "Whatever you do will be insignificant, but it is very important that
>  you do it."  Mahatma Gandhi