Reddit: why aren't people using D?

[Jarrett Billingsley]

On Fri, Jul 24, 2009 at 6:44 PM, Andrei
Alexandrescu<SeeWebsiteForEmail at erdani.org> wrote:
> Bill Baxter wrote:
>>
>> On Fri, Jul 24, 2009 at 2:19 PM, Andrei
>> Alexandrescu<SeeWebsiteForEmail at erdani.org> wrote:
>>>
>>> Jarrett Billingsley wrote:
>>>>
>>>> On Thu, Jul 23, 2009 at 5:56 PM, Michiel
>>>> Helvensteijn<m.helvensteijn.remove at gmail.com> wrote:
>>>>>
>>>>> Eldar Insafutdinov wrote:
>>>>>
>>>>>> from your post:
>>>>>>
>>>>>> property int length {
>>>>>>   get() { return this.len; }
>>>>>>   set(newLen) { this.len = newLen; }
>>>>>>   void opIncrement() { this.len++; }
>>>>>> }
>>>>>>
>>>>>> I don't think that's flexible to overload every operator to get the
>>>>>> best
>>>>>> performance. As Walter likes to say the best way should be the most
>>>>>> obvious. Besides we forgot that D2 allows to return references, which
>>>>>> eliminates the issue.
>>>>>
>>>>> If your property really just hides a private member variable, it was
>>>>> probably for encapsulation purposes or because you want redundant
>>>>> actions
>>>>> to be taken for every access. If you return a reference, you give
>>>>> unlimited
>>>>> and unrestricted access to that variable with only one call, and you
>>>>> might
>>>>> as well not have used a property at all.
>>>>>
>>>>> If your property is derived -- that is, if it doesn't directly mirror a
>>>>> variable --, there is no reference to return.
>>>>>
>>>>> Besides, in D, you can probably use mixins to copy the entire interface
>>>>> of a
>>>>> type into the property without code duplication.
>>>>
>>>> You're suggesting adding something like 25 operator overloads to every
>>>> property.  Can you say "code bloat"?
>>>>
>>>> Why not just use the following solution, which has been proposed
>>>> God-knows-how-many-times and already has precedence in other languages
>>>> (like C#)?
>>>>
>>>> obj.prop op= value;
>>>>
>>>> Simply becomes:
>>>>
>>>> obj.prop.set(obj.prop.get op value);
>>>
>>> I think this would be inefficient in many cases.
>>
>> That is true but I also think:
>> * probably that is the best that can be achieved automatically.
>> * if better can be achieved automatically then the compiler can just
>> do that under the hood.  No user code needs to change.
>> * set(get op value) probably won't be inefficient in some cases.
>> * having a op= b work automatically in an inefficient way is better
>> than forcing the users of the code to make the same ineffecient
>> transformation in their code manually (which is the status quo of
>> property syntax in D).
>>
>> So I think how to make a op= b whizzy fast can be decided later.  And
>> for now set(get op value) is good enough.
>
> Ok, I got convinced.

Have you also seen Michiel's suggestion?

obj.prop op= value;
// auto temp = obj.prop.get();
// temp op= value;
// obj.prop.set(value);

I think this is probably somewhat more correct, in the face of
operator overloading on typeof(temp).  That is, if obj.prop is a
struct that overloads opAddAssign, you'd want "obj.prop += 5" to
really call obj.prop's opAddAssign, rather than its opAdd.