I suspect it's not nearly so rare as you think. For example, it just showed up
in Tom and Mark's new proxy proposal:
> The protect trap is called on Object.{freeze,seal,preventExtensions}(aProxy).
> The operation argument is a string identifying the corresponding operation
> (“freeze”, “seal”, “preventExtensions”). This makes it easy for a handler to
> forward this operation, by e.g. performing Object[operation](obj).
A simple way to abstract out "do this concrete operation" to "do one of the
following set of possible concrete operations" is to pass the name as a string.
Yes, there's a certain aesthetic that says that's icky, but JS makes it so
convenient that it's the obvious thing to do.
Dave
On Oct 17, 2011, at 4:15 PM, Allen Wirfs-Brock wrote:
>
> On Oct 17, 2011, at 3:34 PM, David Herman wrote:
>>
>>
>>> IMHO the single "property name space" of es-current is a feature, not a bug.
>>
>> I tend to agree. There are expressibility problems, too. For example, if you
>> have an object that uses . for its API and [] for some other data, then what
>> do you do when you want to dynamically compute an API name?
>
> In most languages, this would fall into the realm of the reflection API.
>
> What is the actual frequency of such driven API member selection. If it is
> high (particularly, high than the utility of good collections) that we may be
> exposing other problems we need to look at more closely.
>
>
>> I would hope not
>>
>> eval("obj." + computeName())
>>
>> But I don't see any obvious ways out of this that aren't pretty convoluted.
>>
>
> I'll give you four:
>
> 1) Object.getOwnPropertyDescriptor(obj,name).value
> etc.
>
> 2) two new reflection functions:
> Object.getProperty(obj,name)
> Object.setProperty(obj,name,value)
>
> 3) build upon the possible alternative private name property syntax
> let foo='foo';
> obj@foo
> or perhaps
> obj@('foo')
>
> 4) a switch statement:
> switch (computedAPIName) {
> case 'property1':
> obj.property1(/*args */);
> break;
> case 'property2':
> obj.property2(/*args */);
> break;
> case 'property3':
> // etc.
> }
>
> All of these start from the perspective that this sort of reflective API
> access should be quite rare.
>
> Allen
>
>
>
>
>
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