Seth Falcon wrote:
> John Chambers <jmc@r-project.org> writes:
>   
>> As I mentioned, this relates to writing methods for initialize().
>> Imagine someone else extends the class "Ab", for which you wrote a
>> method.  If they add slots to their class and you do not pass down ...
>> to callNextMethod(), then you have blocked users from setting values
>> for those slots in calls to new(), since the ... argument is thrown
>> away by your method.
>>     
>
> If you have written an initialize method, then it is likely because
> you want to do something other than just fill slots.  A subclass will
> most likely need to define its own initialize method and in this case,
> I'm not sure passing ... will matter.
>   
On the contrary, a small change to an existing class often does NOT 
involve any special treatment, just perhaps adding a bit more information.

By breaking the ... argument you force the implementer of this class to 
write an initialize() method whether they want to or not.
>   
>> The other aspect to this is that the last specialized method in your
>> chain of class definitions should end up with: callNextMethod(.Object,
>> ...)  Then the default initialize() method will set values for named
>> slots.
>>     
>
> Unless that isn't the behavior one desires (and I would claim this is
> a rather common situation).  As part of the user interface to the
> class, the developer may want to decouple the intitialization
> interface from specific slot names.
>   
You can do whatever you choose for your class definition.  This is an 
issue of allowing others to extend what you have done in the way that 
_they_ choose.

Again, the point is to avoid the position that I know best and no one 
can extend my class definition by small improvements.  So you block 
users who might manage a simple addition of a slot that they need, but 
would be intimidated by writing an initialize()  method, or more likely, 
would not realize that they were required to do so.

If I sound a little grumpy on this, it's that I think it's an aspect of 
the philosophy of gradual improvement and that philosophy is one of the 
good things about the language, and about the class/method mechanism.
>
> + seth
>
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