why ; ?

[Michael Neumann]

Nick Sabalausky wrote:
 > "Michael Neumann" <mneumann at ntecs.de> wrote in message
 > news:fvvd1a$7p3$1 at digitalmars.com...
 >> terranium wrote:
 >>> Michael Neumann Wrote:
 >>>
 >>>> Another example which leads to hard to read code and potential
 >>>> bugs is (ignoring compiler warnings):
 >>>>
 >>>>      class A
 >>>>      {
 >>>>        int i;
 >>>>
 >>>>        //
 >>>>        // add some 25 lines of code here
 >>>>        //
 >>>>
 >>>>        void foo(int i)
 >>>>        {
 >>>>          // what is "i" here?
 >>>>        }
 >>>>      }
 >>>>
 >>>> This is solved in Ruby by using a separate namespace for instance
 >>>> variables ("@i" for instance variable "i", and "i" for local variable
 >>>> "i").
 >>> In C family languages this is ruled out by naming convention.
 >> Which in the case of using a m_ prefix leads to hard(er) to read code.
 >> And then there is no standard naming convention, and who actually uses
 >> such a naming convention? Without that, you can't easily distinguish a
 >> local variable from an instance variable from a global variable.
 >>
 >
 > In "good" C family languages, the instance variable is referred to by
 > prefixing it with something like "this.". I think there are some that 
do it
 > differently (ECMAScript, IIRC), but I'd argue those ones are making a 
big
 > mistake.
 >
 > However, that does bring up an inconsistancy inherent to the C-style.
 > Following your example, if I do this:
 >
 > class A{
 > int i;
 > void foo(int i) {}
 > void foo() {}
 > void bar() {}
 > }
 >
 > In that case, "i" means one thing if you're in "foo(int)", and 
another thing
 > if you're in "foo()" or "bar()". Of course, you could decide to 
*always* use
 > "this." when referring to an instance variable, but that's kinda 
long, and
 > you still end up with a hidden bug if you decide to use a local var 
named
 > "i" and forget to declare it.

Yeah, you are right. It is inconsitent to define the instance variable
with "i" while accessing it with "@i":

   class A {
     int i;

     void foo(int i) { @i = i; }
   };

But, then it's no less inconsistent than using "this.i".

 > There are things about Ruby I don't like, but the @instanceVar syntax 
is one
 > of the things I think it got spot-on. I would be totally in favor of
 > adopting that.

Btw, I wrote a C++ preprocessor script that during compilation
transparently replaces every occurence of "@" by "this->".
Would be nice to have this build into D directly.

Regards,

   Michael