fun with properties

[teo]

On Wed, 23 Mar 2011 08:28:46 -0600, Kai Meyer wrote:

> On 03/23/2011 06:48 AM, teo wrote:
>> How can I use properties with increment/decrement and +=/-= operators?
>>
>> I did following tests (the errors are from dmd v2.052):
>>
>> class T
>> {
>>      private int _x;
>>      @property
>>      public int x() { return _x; }
>> }
>>
>> void main()
>> {
>>      int[] a;
>>      // case #1.1
>>      a.length++;    // Error: a.length is not an lvalue // case #1.2
>>      a.length += 1; // Ok
>>
>>
>>      auto t = new T();
>>      // case #2.1
>>      t.x++;      // Error: t.x() is not an lvalue // case #2.2
>>      t.x += 1;   // Error: 't.x' is not a scalar, it is a @property
>>      int()
>>                  // Error: incompatible types for ((t.x) += (1)):
>> '@property int()' and 'int'
>>      // case #2.3
>>      t.x()++;    // Error: t.x() is not an lvalue // case #2.4
>>      t.x() += 1; // Error: t.x() is not an lvalue
>> }
>>
>> Basically I want to change the value of a member variable, which is
>> accessed only through a property.
>> It looks like that is partially possible with the length property of
>> dynamic arrays although they probably are implemented in a different
>> way.
> 
> You need a "write" property:
> 
>      @property
>      {
>          public int x() { return _x; } // Read property public void
>          x(int x1) { _x = x1; } // Write property
>      }
> 

I've already tried that, but to no avail. I am getting the errors stated 
above. Can you give me a complete working example please?