On Mar 27, 2012, at 10:36 PM, Kevin Smith <[email protected]> wrote:
> But aren't non-BTFs rare based on your (revised and original) measurements?
>
> When you take out the object literal methods, that's right.
>
> The precise way to say it would be that ~90% of function expressions in the
> code I analyzed were either object literal methods or did not depend on
> dynamic |this|.
>
> That's exactly the reason I'm suggesting lexically bound |this| for "->"
> functions, because outside of "methods" (which already have shorter syntax,
> either via object literal extensions or classes), there doesn't appear to be
> a great need for function expressions with dynamic |this|.
I'm sure this is a bit of a tangent, but the other major related case is
passing a "method" as an argument but needing to retain the correct "this".
Obviously, that is what bind was meant for, but that is inconvenient when
passing methods for the same reason it would be inconvenient for anonymous
functions.
I guess what I'm proposing is a syntax supported version of bind that is
independent of shorter function syntax entirely. Don't hold me to the syntax,
because I don't think its right, its just to give you an idea.
//let say I have some object foo with a method bar that I want called
as a callback
//right now I have to use bind, or wrap the call in an additional
function
needsCallback(foo.bar.bind(foo);
//also happens inside the class itself, and you'll see
needsCallback(this.bar.bind(this));
//and finally, the case we're addressing now
needsCallback(function(x,y){
if(x){
this.doX(x);
else{
this.doY(y);
}
}.bind(this));
What if we had a shorthand for bind that worked in both of these cases
//here the # acts as both a . and bind in one
needsCallback(foo#bar)
needsCallback(this#bar)
//in this case, it obviously doesn't access a property, it just does a
bind
needsCallback(this#function(x,y){
if(x){
this.doX(x);
else{
this.doY(y);
}
});
//or with the new syntax
needsCallback(this#(x,y)->{
...
});
I'm guessing this idea is a stretch or possibly even suggested already and
tossed out, but it came to me as a possibility and I thought I would mention it.
- Russ
>
> kevin
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