not really. you create the function once on module load, assignment is in a
creation:
foo.js:
var Writable = require('stream').Writable
, _write = function(chunk, encoding, callback){
// do something with chunk
// this ref points to a Writable instance
}
module.exports = myCustomStream(){
var s = new Writable()
s._wirte = _write
return s
}
it may be even more performant, because the _write function sits in the
object itself not in it's prototype. A lookup up the prototype chain is
less performant, than a lookup of the 'own' property.
but first you have to benchmark your specific case, before arguing about
performance.
Am Montag, 8. April 2013 04:07:59 UTC+2 schrieb Liam:
>
> Isn't there a cost of assigning a function to an object every time you
> create such an object, vs. assigning to .prototype of a subclass?
> At the very least you're creating a closure around any variables in scope
> at the point of the assignment.
>
>
> On Sunday, April 7, 2013 1:27:50 PM UTC-7, greelgorke wrote:
>>
>> 2. both ways work. you could subclass or just create a Writabel instance
>> and attach a new _write function. It's more a matter of style and applied
>> paradigm. some prefer the mixin-approach, some inheritance. me personally
>> prefer the mixin approach, because it's cleaner and more focused on actual
>> work, than pseudoclass-boilerplating.
>>
>> Am Sonntag, 7. April 2013 21:02:04 UTC+2 schrieb Liam:
>>>
>>> The v0.10 docs don't mention an 'error' event for Stream.Writable. Is
>>> that a docs omission, or an API change?
>>>
>>> Stream.Writable#write() takes a callback that provides an error, but the
>>> callback is described as 'optional'. If errors were only reported this way,
>>> surely it wouldn't be optional?
>>>
>>> Also, the docs don't give an example of defining a custom
>>> Stream.Writable. Should we define a subclass formally, or simply:
>>>
>>> var s = new Stream.Writable()
>>> s._write = function(...) {} // feels odd; I'm used to attaching
>>> functions to prototypes
>>>
>>>
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