division of objects into classes and structures is bad

[Don]

Weed wrote:
> Denis Koroskin пишет:
> 
>>>  80490eb:       8d 85 6c fe ff ff       lea    -0x194(%ebp),%eax
>>>  80490f1:       50                      push   %eax
>>>  80490f2:       8d 85 2c fb ff ff       lea    -0x4d4(%ebp),%eax
>>>  80490f8:       e8 67 ff ff ff          *call   8049064*
>>>  80490fd:       e8 62 ff ff ff          *call   8049064*
>>>     return c2.i;
>>>  8049102:       8b 85 cc fc ff ff       mov    -0x334(%ebp),%eax
>>> ...
>>>
>>>
>>> (in 80490f8 and 80490fd simply two calls successively)
>>>
>>> If structures and classes were same that excellent optimization in any
>>> case would turn out
>> If that's your use case, then your should seriosly reconsider using
>> struct instead of class for your objects.
> 
> Classes always give such overhead if them to use in such quality. For
> example, classes basically cannot be used as any mathematical objects
> using overload of arithmetics. But also not only arithmetics, it it is
> simple as a good example.
> 
>> Alternatively, you can use +=
>> instead.
> 
> Here yes, but if I add classes of different types? Then not to escape
> any more from creation of the temporary object in the heap.
> 
>> Other than that, this is not a convincing argument.
>>
>> Reading many of your posts I came to a conclusion that you are
>> shortsighted and too crazy about performance. What you care about is a
>> premature optimization, which is a root of all the evil. You should
>> ensure that your programm is complete and correct, first and *then*
>> start doing profiling and optimizations.
> 
> The program is already ready. It entirely consists of the various
> mathematics. Approximately %30 times of performance are spent for
> similar superfluous work. On C++ the program will work on %30 faster (I
> hope :)) and on D I am will turn out to do nothing with it.
> 
> 
>> Going back to the topic, dividing user types into two cathegories
>> (structs and classes) is considered modern and right.
> 
> I do not accept such argument:)
> 
>> Some languages
>> lack structs support at all (e.g. Java), but structs are too useful for
>> optimization and language interoperation to drop them in a systems
>> programming language. Some lack classes and try doing everything with
>> structs (C). D takes the best of both worlds.
> 
> Probably I have not understood something, but I do not suggest to refuse
> structures in general. I suggest to allow to create classes on a stack
> as it is made in C++. That is actually to make structures and classes
> same, than they and are, for example, in C++.
> 
> In the initial message I have shown that for perfomance important that
> the class could be transferred and on value. And it not artful premature
> optimisation - objects on value always so are transferred, all
> programmers know it and use when do not wish to allocate a place in a
> heap, that is usually always when the object will live in {}.
> 
> Besides, a class in a stack it is normal - keyword addition "scope" for
> classes too speaks about it.
> 
> Rigidly having divided classes and structures D deprives of the
> programmer of some possibilities which give it C++-like languages. I
> consider that such languages should give all possibilities which allows
> CPU but hiding concrete architecture, otherwise I would choose less
> difficult in use language.

Use classes if you want polymorphism. Otherwise, use structs. It's a 
clear distinction, which is not at all arbitrary -- there are 
significant implications for the generated code.