Re: New metamethod for method lookup

[Mark Hamburg <mark@...>]

On Nov 15, 2009, at 3:54 PM, Alex Davies wrote:

> One issue I have with the idea is there is no one way to index in Lua. Sometimes, even for function calls, you have to index from a variable in a string []. Other times the method : call is fine.  Sometimes you just want to pass a different self, so . is applicable.  So for this to work you'd need to add a "getmethod(table, key)" function, which is a bit tacky imo, but would work.

I called that out though, I think that part of the motivation for doing this actually argues against support for calling a method with a different self, so one wants:

	mcall( obj, mkey, ... )	or obj:[ mkey ]( ... )

The latter has the benefit of being able to compile to the same VM code and doesn't require a function call. It's also probably more efficient than the current

	obj[ mkey ]( obj, ... )

One also wants mbind( obj, mkey ) which returns a closure to invoke the method on the object. This could be sugared to obj:mkey though implementing it is more than just an isolated tweak to the compiler.

Thanks for digging up the info on __proxy. This solves the properties v methods problem and does so without particularly complicating the semantics, but it does not provide the other benefits of __methindex with respect to things like making sure that methods are always accessed as methods.

Mark