Readonly class members

[Chris Miller]

On Thu, 14 Sep 2006 09:59:56 -0400, Georg Wrede <georg.wrede at nospam.org>  
wrote:

>> From time to time I wish that C++ would have a readonly specifier that   
>> works like this:
>>  class Obj {
>>     void f() {
>>         int m_size = 10;  //ok
>>     }
>>      readonly int m_size;
>> }
>>  void func() {
>>     Obj o = new Obj;
>>     int v;
>>      v = o.m_size;  //ok
>>     o.m_size = 5;  //error
>> }
>
>> 'm_size' can be accessed inside 'Obj' as normal, but outside the class
>> the variable cannot be modified. Of course, I could provide a read
>> property (that is, a function in C++) for accessing 'm_size' (in
>> addition to a write property), but when it's not necessary, this way is
>> simplier (and a little bit faster, etc.).
>>  In D this, however, is not needed because you can use properties to  
>> wrap
>> member variables.
>> (Hopefully the properties will be extended to support the same methods
>> that can be applied to variables also... ;) )
>
> Hmm. IMHO, this would be very easy to implement in the compiler. It  
> would make class definitions clearer, and in many cases would lessen the  
> need to write code.
>
> Just off-hand I can imagine quite a few situations where I'd use this.

D's const has this ability..
class Obj
{
    this(int foo) { m_size = foo; }
    const int m_size;
}