Old problem with performance

[downs]

Weed wrote:
> Christopher Wright пишет:
>> Weed wrote:
>>> Christopher Wright пишет:
>>>> Weed wrote:
>>>>> (Has started here:
>>>>> http://www.digitalmars.com/webnews/newsgroups.php?art_group=digitalmars.D&article_id=81359)
>>>>>
>>>>>
>>>>>
>>>>> To me still does not give rest performance of classes (in comparison
>>>>> with C++ or with D structs)
>>>> On my system, your struct example averaged 0.36 seconds, and your class
>>>> example averaged 0.38 seconds.
>>>>
>>>> Your benchmark is flawed in three ways:
>>>> 1. You're timing allocations in the class example. Use opAddAssign to
>>>> avoid it.
>>> Earlier I proved that it is impossible. For example here in such
>>> expression:
>>> ==============
>>> space_ship_1.calculatePathTo("Moon").getCheckpoint(3).getCoords;
>>>
>>> In this example we create a temporary class "path", create temporary
>>> class "checkpoint" and we take coords of checkpoint of this path. It is
>>> not expedient to us to store all this path and checkpoint because it is
>>> vary.
>>> ==============
>> In that example, you can use structs instead of classes. Your response
>> to that is that structs do not participate in polymorphism.
>>
>> There was a suggestion elsewhere like this:
>> interface IPathResolver
>> {
>>     Checkpoint getCheckpoint(Path* path, int i);
>> }
>>
>> struct Path
>> {
>>     char[] path;
>>     // any other info you need....
>>     IPathResolver resolver;
>>     Checkpoint getCheckpoint(int value)
>>     {
>>         return resolver.getCheckpoint(this, value);
>>     }
>> }
>>
>> This way, you only allocate once for each type you need, you have
>> polymorphism, and you can put stuff on the stack for quick access.
> 
> And if I need some different such combinations? For each it is necessary
> to write such 8-10 lines? This is terrible!

I'm sure you can do something with templates. :)