2008/9/18 Mark S. Miller <[EMAIL PROTECTED]>:
> The Redmond mtg is fast approaching. We'd like to put out an official
> for-Redmond-mtg draft of the ES3.1 spec by then. I had volunteered to write
> the spec for Function.prototype.bind(). Long term, I think we all agree we'd
> like to see this spec and many others self-hosted in EcmaScript. However,
> the discussion of self-hosting issues makes clear that this ain't gonna
> happen in time for ES3.1.
>
> So what we need now is a spec for Function.prototype.bind() in the peculiar
> pseudo-code style -- combining the worst of COBOL and assembly language --
What pseudo-code style? This:
Function.prototype.bind( context, [ preArg1 [, preArg1 [,...]]])
?
> used in the rest of the spec. Unfortunately, I won't have time between now
> and then. Would anyone care to contribute some text? Please?
>
I'm not sure exactly what you're looking for so I've typed only a
little. Is this in the right direction:-
================================================
Function.prototype.bind( context, [ preArg1 [, preArg1 [,...]]])
Returns a function that invokes this function. The |context| argument
determines the execution context of the returned function. Arguments
1..n are used for values of parameter variables to this function.
Example:
var brendan = { name : "Brendan" };
function sayHelloTo(name) {
return "Hi " + name + ", my name is " + this.name + ".";
}
brendansGreeting = sayHelloTo.bind(brendan);
brendansGreeting("Mark");
returns
"Hi Mark, my name is Brendan."
Methods |Function.prototype.call| and |Function.prototype.apply| do
not affect the |this| value of a bound function. Thus:
brendansGreeting.call(null, "Mark");
returns
"Hi Mark, my name is Brendan."
[insert_algorithm_steps_here]
The |length| property of Function.prototype.bind is 1.
================================================
A self-hosted version:
/**
* @param {Object} context the |this| value to be used.
* @param {arguments} [1..n] optional arguments that are
* prepended to returned function's call.
* @return {Function} a function that uses |context| as the this
* value for the returned function and arguments 1..n for values
* of parameter variables to this function.
*/
Function.prototype.bind = function(context) {
var fn = this,
ap, concat, args,
isPartial = arguments.length > 1;
// Strategy 1: just bind, not a partialApply
if(!isPartial) {
return function() {
if(arguments.length !== 0) {
return fn.apply(context, arguments);
} else {
return fn.call(context); // faster in Firefox.
}
};
} else {
// Strategy 2: partialApply
ap = Array.prototype,
args = ap.slice.call(arguments, 1);
concat = ap.concat;
return function() {
return fn.apply(context,
arguments.length === 0 ? args :
concat.apply(args, arguments));
};
}
};
================================================
?
Garrett
> --
> Cheers,
> --MarkM
>
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> https://mail.mozilla.org/listinfo/es-discuss
>
>
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