What do you mean “isn't actually bound”? The function being defined using colon syntax doesn't close over self, since it's a parameter—but functions defined within that function will close over the self parameter, since it's a local from an enclosing scope:
foo = { x = 3 }
function foo:bar(baz)
return function(thud)
return thud + baz + self.x
end
end
womble = foo:bar(4)
womble(7) --> 14
Python I believe also closes over self as a variable, and Ruby has similar behavior for local procs, even though « self » is a special form in Ruby.
This is in distinct contrast to JavaScript, where the value of the special form « this » goes nuts inside closures because it's attached to the function:
Ah, okay, I see what you mean. Yeah, you're absolutely right there. Point conceded.
Mentally, I was separating Javascript and Lua from Ruby because while the caller is explicitly passed in Javascript and Lua (either via call/apply, or as a parameter), Ruby methods are implicitly aware of their scope (and can't really be referentially passed around like Javascript or Lua methods). Lua "methods" aren't aware of their scope (though closures are.
Ruby methods bound to their objects can be passed around; it's just a bit more cumbersome, in the form of « m = obj.method(:foo) » followed by « m.call(…) ». You can even do « m = :foo.to_proc » in recent Ruby and be able to « m.call(obj, …) »; this is quite useful for things like « [1, 2, 3].inject(&:+) ».
So we have that Python's dot always binds, Ruby's dot always calls, and Lua's dot is always a table lookup, with Lua's colon being a separate syntax for (always) the compound operation with injected self-argument.
And then JavaScript is the schizophrenic one: « obj.foo(bar) » is not the same as « var y = obj.foo; y(bar) ». Property lookup and function call insert a hidden step between them when and only when directly composed, and a function call without an immediately adjacent property lookup in a way injects the opposite step of making « this » in the callee be the global object (I think). “Politicians lie in cast iron sinks.”
This is in distinct contrast to JavaScript, where the value of the special form « this » goes nuts inside closures because it's attached to the function:
So in what way are you placing Lua and JavaScript together, and Python and Ruby together?[slightly rearranged for clarity]