fun with properties

[Kai Meyer]

On 03/23/2011 10:09 AM, teo wrote:
> 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?

Sorry, you're right. I don't think properties are done, especially given 
these features don't work as expected.