Rails spinoffs - Sep 2005 - Preventing/allowing exceptions to occur in Element.add/remove ClassName

Hello everyone !

Thomas asked me to discuss here the behavior of Element.addClassName, as 
relating to ticker #2232 [1].  In HEAD, if the element passed-in to 
Element.addClassName does not exist, an exception is thrown, and script 
execution stops there.

I believe this is inconsistent with other functions:
Object.extend(Element, {
   hasClassName: function(element, className) {
     element = $(element);
     if (!element)
       return;
     //...
   },

   removeClassName: function(element, className) {
     element = $(element);
     if (!element)
       return;
     //...
   },

   addClassName: function(element, className) {
     element = $(element);
     Element.removeClassName(element, className);
     //...
   },
}

As you can see, both hasClassName and removeClassName prevent an 
exception from occuring if the element does not exist.  Either make all 
three functions throw an exception, or make all three more resilient in 
the face of possible errors (2/3 of the way there !).  In my mind, 
addClassName is an omission...  It should be standardized.

Bye !
Fran?ois

[1] http://dev.rubyonrails.org/ticket/2232

On Monday 26 September 2005 02:52, Fran?ois Beausoleil wrote:
> Thomas asked me to discuss here the behavior of Element.addClassName,
> as relating to ticker #2232 [1].  In HEAD, if the element passed-in
> to Element.addClassName does not exist, an exception is thrown, and
> script execution stops there.
>
> I believe this is inconsistent with other functions:
>    hasClassName: function(element, className) {
>    removeClassName: function(element, className) {
>    addClassName: function(element, className) {

Will these zombies ever die? I wrote and send them to Sam months ago 
when I didn''t know about the much better Element.Class. I''ve
even
supplied a patch that replaces the former with the latter. Until now to 
no effect, alas.
> As you can see, both hasClassName and removeClassName prevent an
> exception from occuring if the element does not exist.  Either make
> all three functions throw an exception, or make all three more
> resilient in the face of possible errors (2/3 of the way there !). 
> In my mind, addClassName is an omission...  It should be
> standardized.
Let them all throw exceptions. These are low level functions. You really 
want to be notified when something goes wrong. If missing elements 
should be ignored, that''s fine, but a job for a higher level where this
policy is set.

Michael

-- 
Michael Schuerig                                 Life is what happens 
mailto:michael@schuerig.de                  While you''re making plans
http://www.schuerig.de/michael/    --Kevin Gilbert, A Long Day''s Life

+1

Also, i''m using the mentioned Element.Class.XXX functions
that currently reside in util.js.

Thomas

Am 26.09.2005 um 03:18 schrieb Michael Schuerig:
> On Monday 26 September 2005 02:52, Fran?ois Beausoleil wrote:
>> As you can see, both hasClassName and removeClassName prevent an
>> exception from occuring if the element does not exist.  Either make
>> all three functions throw an exception, or make all three more
>> resilient in the face of possible errors (2/3 of the way there !).
>> In my mind, addClassName is an omission...  It should be
>> standardized.
>>
>
> Let them all throw exceptions. These are low level functions. You  
> really
> want to be notified when something goes wrong. If missing elements
> should be ignored, that''s fine, but a job for a higher level where
> this
> policy is set.