Private visible?

[Bruno Medeiros]

Jari-Matti Mäkelä wrote:
> xs0 wrote:
>> class Number {
>>     public void setVal(int val) { ... }
>>     public void setVal(long val) { ... }
>> }
>>
>> class IntNumber : Number {
>>     public void setVal(int val) { ... }
>>     private void setVal(long val) { assert(0); }
>> }
>>
>> Number a = new IntNumber();
>> a.setVal(10L);
>>
>> Now, not only does the last line compile, it also calls the wrong
>> function and fails to fail.
> 
> And casting back to IntNumber makes it again private. No OOP language
> should do that. It's against the rules of polymorphism.
> 

Agreed, it does seem that contravariant (method) protection levels 
should not be allowed.

> 
>> As for overloading issues, as far as I am concerned, feel free to
>> require all methods with the same name to have the same protection;
>> anything else is poor taste anyway.
> 
> Really? Then how do you hide the previous method implementation?
> 
> class A {
>   protected pm() { ... }
> }
> class B : A {
>   // ugly, isn't it :(
>   protected pm() { assert(0); /* subclasses: do not use this */ }
>   public pm2() { super.pm(); ... }
> }
> 
> vs.
> 
> class A {
>   protected pm() { ... }
> }
> class B : A {
>   public pm() { super.pm(); ... }
> }
> 

He said overload, not override.

-- 
Bruno Medeiros - CS/E student
http://www.prowiki.org/wiki4d/wiki.cgi?BrunoMedeiros#D