Re: Odd behavior involving function.apply()
- From: "Jeff Stewart" <object01@xxxxxxxxx>
- Date: 19 Jul 2006 04:46:53 -0700
The 'secret' is designed to illustrate that a hidden member could be
introduced into the created object using this pattern. It's based on
what I read on Crockford.com.
As for the intent, considering JavaScript really doesn't have "types",
I'm trying to create a new -object-. I'm obsessed lately with the idea
that JavaScript 1) was never designed to support classes (yet everyone
tries to force it to), 2) supports -prototypal- inheritance instead of
class-based inheritance, and 3) prototypes are -not- classes.
So the object() function is supposed to create either 1) objects with
an "instance" semantic attached to them, or 2) patterns -- prototypes
-- upon which other objects are based. But it should be composable --
again, the philosophy I'm adopting is that objects inherit from
prototypes, not classes/types. And, thusly, an object/instance created
from a prototype should be capable of acting as a prototype itself.
object() should be the root of this functionality: any source object,
by virtue of JavaScript, can be used as a prototype to create any other
object which can be said to "inherit" from the source object. I'm
trying to get back to basics amidst all the half-baked classical
inheritance implementations that do many things well but not the whole
thing with excellence. But though I'm getting back to basics, I still
want to try and introduce things like information hiding into the mix.
object() is a very hairy mutation of the function Crockford discusses
here: http://javascript.crockford.com/prototypal.html. I wasn't
satisfied with that method because it didn't support a more intuititve
initialization mechanism.
I had something I liked until I tried nested creation. In this
particular problem, I can't understand how the addition of one
property, subObject can so dramatically alter its owner object. I
thought I'd isolated all my execution contexts properly by latching
onto 'this' in all the right places using local variables, but somehow
the -nested- call to object() ended up modifying the object that
-owned- the call. How was that boundary violated?
As for it being a scope quagmire, well, in my defense, it -is-
JavaScript. Scope stopped being an easy concept when I was introduced
to the wild world of closures. :)
--
Jeff S.
Jeremy wrote:
Jeff Stewart wrote:
<snipped long, complicated test case>
Why doesn't this work more intuitively?
The best kind of irony is unintentional irony. That made me laugh out
loud :-)
As for your problem - your code looks like a scope quagmire to me.
Shouldn't you be assigning properties to your object rather than
creating them as local variables (as with "secret")? I don't fully
understand what you're trying to do - are you trying to create an
*object* that inherits from Prototype, or a new *type* that inherits
from Prototype?
Can you explain what you're trying to do? Maybe there's an analogous
pattern in a different language that you're trying to emulate? Whatever
it is, there is probably a simpler way.
Jeremy
.
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- From: Jeff Stewart
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