Re: Category or Protocol? (sidetrack)

FROM : Scott Ellsworth
DATE : Fri Apr 22 02:01:09 2005

On Apr 21, 2005, at 4:45 PM, Ondra Cada wrote:

> John,
>
> On 21.4.2005, at 1:41, John Stiles wrote:
>
>

>> theoretically if you had two classes with a Foo() method, you 
>> could add a parameter to Foo() in class A and not class B, and the 
>> editor could find all the instances of the Foo() method in class A 
>> and not class B. This isn't possible with grep :)
>>

>
> More than that: in fact, it is not possible *at all* :))


Actually, it is possible.  I do this all the time with IDEA.

If you add a parameter to a base class, it asks if you want it 
propagated to the implementations in all of the implementing 
classes.  Similarly, if you change a method in an interface, it 
updates all the implementing classes, and vice versa.  It also finds 
all usages of the method via instances of the class, subclasses, and 
via interfaces.

> (Not even with Java, see reflection/NSSelector/action-target/first 
> responder stuff... And of course, even *considerably* less with 
> ObjC or another decent language.)


You can certainly break reflection, but catching direct method calls 
covers a lot of ground.  The majority of cases, in my experience.

Believe me, this makes life run a lot faster, and does reward typical 
usage of the Java type system.

Scott