[fpc-devel] for-in-index loop

[Sven Barth]

On 27.01.2013 16:27, luiz americo pereira camara wrote:
> 2013/1/26 Sven Barth <pascaldragon at googlemail.com>:
>> On 26.01.2013 12:52, Alexander Klenin wrote:
>>>
>>> On Sat, Jan 26, 2013 at 10:50 PM, Sven Barth
>>> <pascaldragon at googlemail.com> wrote:
>>>>>
>>>>> Generics was implemented without my knowledge. I only found out when
>>>>> suddenly
>>>>> the classes unit had been changed to use them. After a horrible
>>>>> discussion, this was reversed, because of the drop in speed you got when
>>>>> using generics.
>>>>
>>>>
>>>> Ah! So that is where those ifdefs in classes come from :) I always
>>>> wondered...
>>>>
>>> Is the drop still present/essential? Perhaps optimizer is now good
>>> enough to drop those ifdefs?
>>
>>
>> Someone would need to test this. It could be that the generic variant is
>> less optimal, because the generic list is built upon a list that handles
>> pointers...
>>
>
> I did some test with generics last year:
> http://lazarusroad.blogspot.com.br/2012/06/cost-of-using-generics.html
>
> I would not use in classes unit

That's mostly about the "duplication" problem, which is known (maybe 
I'll try to improve the situation some time). What would have been more 
interesting is the performance of the generated code compared with e.g. 
a TStringList or a TObjectList.

Regards,
Sven