Hi Brad,
> The contract states that Enumerable#reject "Returns all the elements
> for which the iterator returned false".
Here's the opening line of the Enumerable#reject docs:
reject(iterator[, context]) -> Array
Similarly, findAll (the one we started with, via its alias filter):
findAll(iterator[, context]) -> Array
That's not an assumption, that's a documented return value. Changing
these to return a Hash if the original is a Hash breaks the contract
and breaks compatibility with previous releases. Whereas getting the
result you want is trivial:
result = $H(originalHash.reject(...));
> It's entirely intuitive that...
I'm not talking intuitive vs. non-intuitive (it's far too subjective),
I'm talking the current documented (and implemented!) behavior.
Remember that Enumerable is a contract, and code dealing with an
Enumerable may not happen to know that it's dealing with a Hashy kind
of Enumerable. :-)
I do agree -- not that it matters! ;-) -- that for (say) 2.0, an
argument can be made for changing Enumerable to say that for these
kinds of methods, it returns an Enumerable (not an Array), and that
concrete classes should (where appropriate) return the same type as
the original. But (due respect to kangax) to me that's not a bug,
that's a request for API enhancement, and not the kind of thing to do
in a dot release or by making Hash a special case.
FWIW,
--
T.J. Crowder
tj / crowder software / com
Independent Software Engineer, consulting services available
On Feb 3, 10:20 pm, Brad <[email protected]> wrote:
> The contract states that Enumerable#reject "Returns all the elements
> for which the iterator returned false". It's entirely intuitive that
> it will return the same data type as the object it was called on.
> Otherwise Hash#reject() is practically useless.
>
> The only part of the documentation that is wrong is the assumption
> that it will always return an Array. Perhaps that was an oversight
> when Hash was left out as a subclass of Enumerable in the
> documentation.
>
> Ruby fixed their documentation:
> Hash#reject:http://www.ruby-doc.org/core/classes/Hash.html#M002901
> Enumerable#reject:http://www.ruby-doc.org/core/classes/Enumerable.html#M003157
>
> On Feb 3, 1:56 pm, "T.J. Crowder" <[email protected]> wrote:
>
> > Kangax,
>
> > > Didn't we establish that this is a bug? ; )
>
> > Not as far as I'm concerned it isn't. It returns what its documented
> > contract says it returns. The only error IMHO is in the
> > interpretation that it would do something other than what the
> > documentation says it will do. You're not suggesting it should break
> > the Enumerable contract, are you?
>
> > -- T.J. ;-)
>
> > On Feb 3, 7:03 pm, kangax <[email protected]> wrote:
>
> > > On Feb 3, 1:54 pm, Brad <[email protected]> wrote:
>
> > > > TJ, thanks for correcting the docs. I hadn't noticed that error
> > > > either.
>
> > > > Are you suggesting that there no intersection of Prototype and Ruby
> > > > communities? I only know of Prototype because of Ruby on Rails.
>
> > > > Let's take Hash#reject() as an example. Let's say I'm moving server-
> > > > side Ruby code to my Prototype-enhanced client-side.
>
> > > > Ruby code:
> > > > { "a" => 100, "b" => 200, "c" => 300 }.reject {|key, value| key ==
> > > > "b" }
> > > > => {"a"=>100, "c"=>300}
>
> > > > Translated to Javascript:
> > > > $H({ "a": 100, "b": 200, "c": 300 }).reject(function(i) { return i.key
> > > > == "b" })
> > > > => [["a", 100], ["c", 300]]
>
> > > > Prototype returns an array? What good is an array if I started with a
> > > > hash? It is intuitive that a reject() method returns a subset of the
> > > > original data structure and not convert it to an entirely different
> > > > one.
>
> > > Didn't we establish that this is a bug? ; )
>
> > > --
> > > kangax
>
>
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Prototype & script.aculo.us" group.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to
[email protected]
For more options, visit this group at
http://groups.google.com/group/prototype-scriptaculous?hl=en
-~----------~----~----~----~------~----~------~--~---
