Rails spinoffs - Nov 2007 - Explicit extension of array prototype with Enumerable methods

Background: As is well known, some code is broken by the useful
extensions that prototype.js adds to the Array prototype.  In
particular the "for (var x in array)" idiom that some libraries like
to use.
(Due to design flaw in Javascript itself, the for loop iterates not
only over the elements of the array but also the non-built in
functions added by prototype.  This breaks code that doesn''t expect
functions.)

I''m happy to rewrite my code to use the prototype idioms, but I
can''t
rewrite every library I might want to call that uses the broken idiom.

It''s a fairly simple matter to modify prototype.js so that, rather
than modifying the Array.prototype, individual arrays are extended
explicitly by the $A function only when I want them to.  I get the
extended array behavior when I want it, and can use vanilla arrays
when I call out to third party code.

It seems like enough people might want this behavior that it couldbe
added as an option on the core prototype.js-- add some sort of switch
so that the auto-extend behavior on Arrays can be turned off in favor
of the explicit model described here.




--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Spinoffs" group.
To post to this group, send email to
rubyonrails-spinoffs-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-spinoffs-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-spinoffs?hl=en
-~----------~----~----~----~------~----~------~--~---

Hi,

Andrew posted an excellent write-up on this issue:

http://www.andrewdupont.net/2006/05/18/javascript-associative-arrays-considered-harmful/

and it''s been discussed numerous times in the mailing list already.

Adding such an option to Prototype isn''t planned and probably never
will, as mistakenly using for...in loop to iterate over array is a
practice that''s thankfully disappearing.

Best,

Tobie


On Nov 28, 10:12 pm, PhilBo
<philbo...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> Background: As is well known, some code is broken by the useful
> extensions that prototype.js adds to the Array prototype.  In
> particular the "for (var x in array)" idiom that some libraries
like
> to use.
> (Due to design flaw in Javascript itself, the for loop iterates not
> only over the elements of the array but also the non-built in
> functions added by prototype.  This breaks code that doesn''t
expect
> functions.)
>
> I''m happy to rewrite my code to use the prototype idioms, but I
can''t
> rewrite every library I might want to call that uses the broken idiom.
>
> It''s a fairly simple matter to modify prototype.js so that, rather
> than modifying the Array.prototype, individual arrays are extended
> explicitly by the $A function only when I want them to.  I get the
> extended array behavior when I want it, and can use vanilla arrays
> when I call out to third party code.
>
> It seems like enough people might want this behavior that it couldbe
> added as an option on the core prototype.js-- add some sort of switch
> so that the auto-extend behavior on Arrays can be turned off in favor
> of the explicit model described here.
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Spinoffs" group.
To post to this group, send email to
rubyonrails-spinoffs-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-spinoffs-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-spinoffs?hl=en
-~----------~----~----~----~------~----~------~--~---

I appreciate these arguments.

However, this is makes it difficult for Firefox toolbar authors to use
prototype.

Popular toolbars like the Facebook toolbar do in fact use the "for (p
in a)" idiom.

Because all toolbars in Mozilla share a common Array prototype, this
means that any toolbar that uses prototype will break such toolbars.
You could argue that this in part a design flaw of Mozilla that
toolbars are not more isolated from one another, but there''s not too
much I can do about that.

On Nov 28, 2:29 pm, Tobie Langel
<tobie.lan...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> Hi,
>
> Andrew posted an excellent write-up on this issue:
>
> http://www.andrewdupont.net/2006/05/18/javascript-associative-arrays-...
>
> and it''s been discussed numerous times in the mailing list
already.
>
> Adding such an option to Prototype isn''t planned and probably
never
> will, as mistakenly using for...in loop to iterate over array is a
> practice that''s thankfully disappearing.
>
> Best,
>
> Tobie
>
> On Nov 28, 10:12 pm, PhilBo
<philbo...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
> > Background: As is well known, some code is broken by the useful
> > extensions that prototype.js adds to the Array prototype.  In
> > particular the "for (var x in array)" idiom that some
libraries like
> > to use.
> > (Due to design flaw in Javascript itself, the for loop iterates not
> > only over the elements of the array but also the non-built in
> > functions added by prototype.  This breaks code that doesn''t
expect
> > functions.)
>
> > I''m happy to rewrite my code to use the prototype idioms, but
I can''t
> > rewrite every library I might want to call that uses the broken idiom.
>
> > It''s a fairly simple matter to modify prototype.js so that,
rather
> > than modifying the Array.prototype, individual arrays are extended
> > explicitly by the $A function only when I want them to.  I get the
> > extended array behavior when I want it, and can use vanilla arrays
> > when I call out to third party code.
>
> > It seems like enough people might want this behavior that it couldbe
> > added as an option on the core prototype.js-- add some sort of switch
> > so that the auto-extend behavior on Arrays can be turned off in favor
> > of the explicit model described here.
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Spinoffs" group.
To post to this group, send email to
rubyonrails-spinoffs-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-spinoffs-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-spinoffs?hl=en
-~----------~----~----~----~------~----~------~--~---