On Apr 21, 2012, at 1:38 PM, Angus Croll wrote:
> >>a function shouldn’t work radically (and silently!) different depending on
> >>how it is invoked
>
> every current JS function behaves exactly this way :-)
No, not at all. What Axel is saying is that you're proposing a new distinction
that *does not exist* in JS. You cannot distinguish whether a function was
called as a method, as a function, or via .call/.apply. There's no way to tell.
All you have is the receiver value bound to `this`, however it was passed in.
Your function can decide whether or not to disregard the receiver entirely, but
it can't tell where it came from.
The caller has the freedom to choose how it *provides* the receiver:
f()
obj.m = f; obj.m()
f.call(obj)
f.apply(obj, [])
but the callee can't tell the difference between f.call(null) and f().
> I'm painfully aware that I sound like a broken record on this, but
> introducing a hard-bound function option while continuing to suport
> dynamic-bound functions everywhere else is not going to simplify anything.
> Another function should not need to know how its function arguments were
> created in order to work properly - thats a terrible anti-functional
> anti-pattern!
There's no difference whatsoever between a function with a lexically-bound
`this` and a function that completely disregards its `this` argument. This is
simply a reality of JavaScript today and forever: every function has an API
that indicates what it expects of its `this` argument and what it will do with
it. If you write a function that ignores its `this` argument, your callers have
to know that they can't change your function's behavior by passing a different
`this`.
Put differently: the lexical `this` syntax is a convenient way to create a
non-method function, a function that ignores its receiver.
Dave
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