Consider following:

class A
{
  int m;
  void opAddAssign(int n) { m += n; }
}

class B
{
  A a;
  this() { a = new A; }
  A Prop() { return a; }
}

void main()
{
  B b = new B;
  b.Prop += 3;
}

I get a compilation error (dmd v2.037):

test.d(17): Error: 'b.Prop' is not a scalar, it is a A()
test.d(17): Error: incompatible types for ((b.Prop) += (3)): 'A()' and
'int'

Am I doing something wrong, or is this a known issue with opAddAssign and/ or properties?

On Tue, 29 Dec 2009 09:01:38 -0500, teo <teo.ubuntu.remove@yahoo.com> wrote:

> Consider following:
>
> class A
> {
>   int m;
>   void opAddAssign(int n) { m += n; }
> }
>
> class B
> {
>   A a;
>   this() { a = new A; }
>   A Prop() { return a; }
> }
>
> void main()
> {
>   B b = new B;
>   b.Prop += 3;
> }
>
> I get a compilation error (dmd v2.037):
>
> test.d(17): Error: 'b.Prop' is not a scalar, it is a A()
> test.d(17): Error: incompatible types for ((b.Prop) += (3)): 'A()' and
> 'int'
>
> Am I doing something wrong, or is this a known issue with opAddAssign and/
> or properties?

This is part of the issue with properties that will be fixed with the @property annotation.

try

b.Prop() += 3;

-Steve

On Tue, 29 Dec 2009 09:10:14 -0500, Steven Schveighoffer <schveiguy@yahoo.com> wrote:

> On Tue, 29 Dec 2009 09:01:38 -0500, teo <teo.ubuntu.remove@yahoo.com> wrote:
>
>> Consider following:
>>
>> class A
>> {
>>   int m;
>>   void opAddAssign(int n) { m += n; }
>> }
>>
>> class B
>> {
>>   A a;
>>   this() { a = new A; }
>>   A Prop() { return a; }
>> }
>>
>> void main()
>> {
>>   B b = new B;
>>   b.Prop += 3;
>> }
>>
>> I get a compilation error (dmd v2.037):
>>
>> test.d(17): Error: 'b.Prop' is not a scalar, it is a A()
>> test.d(17): Error: incompatible types for ((b.Prop) += (3)): 'A()' and
>> 'int'
>>
>> Am I doing something wrong, or is this a known issue with opAddAssign and/
>> or properties?
>
> This is part of the issue with properties that will be fixed with the @property annotation.
>
> try
>
> b.Prop() += 3;

Eventually, marking Prop as a @property should also work (haven't tested it, it may work now):

@property A Prop() { return a; }

...

b.Prop += 3; // compiles

-Steve

On Tue, 29 Dec 2009 09:12:15 -0500, Steven Schveighoffer wrote:

> On Tue, 29 Dec 2009 09:10:14 -0500, Steven Schveighoffer <schveiguy@yahoo.com> wrote:
> 
>> On Tue, 29 Dec 2009 09:01:38 -0500, teo <teo.ubuntu.remove@yahoo.com> wrote:
>>
>>> Consider following:
>>>
>>> class A
>>> {
>>>   int m;
>>>   void opAddAssign(int n) { m += n; }
>>> }
>>>
>>> class B
>>> {
>>>   A a;
>>>   this() { a = new A; }
>>>   A Prop() { return a; }
>>> }
>>>
>>> void main()
>>> {
>>>   B b = new B;
>>>   b.Prop += 3;
>>> }
>>>
>>> I get a compilation error (dmd v2.037):
>>>
>>> test.d(17): Error: 'b.Prop' is not a scalar, it is a A() test.d(17):
>>> Error: incompatible types for ((b.Prop) += (3)): 'A()' and 'int'
>>>
>>> Am I doing something wrong, or is this a known issue with opAddAssign
>>> and/
>>> or properties?
>>
>> This is part of the issue with properties that will be fixed with the @property annotation.
>>
>> try
>>
>> b.Prop() += 3;

Thanks. This trick works, but it looks a bit weird.


> 
> Eventually, marking Prop as a @property should also work (haven't tested
> it, it may work now):
> 
> @property A Prop() { return a; }
> 
> ...
> 
> b.Prop += 3; // compiles
> 
> -Steve

Unfortunately it doesn't:

test.d(17): Error: 'b.Prop' is not a scalar, it is a @property A()
test.d(17): Error: incompatible types for ((b.Prop) += (3)): '@property A
()' and 'int'

On Tue, 29 Dec 2009 13:44:18 -0500, teo <teo.ubuntu.remove@yahoo.com> wrote:

> On Tue, 29 Dec 2009 09:12:15 -0500, Steven Schveighoffer wrote:
>>
>> Eventually, marking Prop as a @property should also work (haven't tested
>> it, it may work now):
>>
>> @property A Prop() { return a; }
>>
>> ...
>>
>> b.Prop += 3; // compiles
>>
>> -Steve
>
> Unfortunately it doesn't:
>
> test.d(17): Error: 'b.Prop' is not a scalar, it is a @property A()
> test.d(17): Error: incompatible types for ((b.Prop) += (3)): '@property A
> ()' and 'int'
>

It will evenutally, probably within the next couple releases.

-Steve