Dereferencing void pointers: why not?

[Vladimir Panteleev]

The Pascal/Delphi language has a nice feature - it can operate (within limits) on typeless data. This is similar to void pointers, but without the pointer clutter (so is in effect "void references"). Some examples:

1) Using a void pointer reference

Unlike in C/C++/D, you can dereference a void pointer (which in Pascal is represented by the "Pointer" type).
This allows me to write instead of:
  PInteger(P)^ := 5;
this:
  Integer(P^) := 5;

The difference in Pascal is more significant since you must define an integer pointer type :)
In a C-like language, it would be from:
  *cast(int*)p = 5;
to
  cast(int)*p = 5;
Less asterisks, less strain to the eye :) This may become worth it when the cast expressions grow long and nested.

2) Typeless function parameters

You can write something like this:
  procedure Test(var Data);

Any mutable (non-const) value converts implicitely to that "void" type.
You can also use "const" instead of "var".

I guess in D it would be declaring such a function argument using "ref void Data", OSLT.

What can you do with such a reference? Well,
 - you can cast it to something immediately useable
 - you can get the address of it (void*)
 - you can pass it on to other functions

Thus, it's just a little bit of syntax sugar and flexibility that fits in nicely in the type system. 

-- 
Best regards,
 Vladimir                          mailto:thecybershadow at gmail.com