Extended Type Design.

[Bruno Medeiros]

Tyler Knott wrote:
> Bruno Medeiros wrote:
>>
>> Huh? Wait a second, but won't D have the same issue, albeit with 
>> 'final'? For example, suppose you have:
>>   final Foo foo;
>> then what is:
>>   typeof(&foo)
>> ?
>>
> 
> invariant Foo* or const Foo*, depending on whichever is most appropriate 
> for the situation.  I'd guess that invariant Foo* would be the default 
> because it's semantically closest to what is being expressed (a pointer 
> to immutable data), though const Foo* is also allowable because you 
> can't modify data through const pointers either.

Let's suppose it's  const Foo*  (the less restrictive option). Even so, 
you will be restricting the type more than necessary, thus loosing some 
range of freedom. Because with  const Foo*  you can't change members of 
Foo*, while with final Foo, you can change members of foo. I.e.:

   final Foo foo;
   foo.x = 2;   // ok

   typeof(&foo) fooptr = &foo;
   (*fooptr.x) = 2;   // not allowed

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