data-oriented struct abstraction ?

[short2cave via Digitalmars-d-learn]

On Saturday, 30 May 2015 at 12:34:21 UTC, Rikki Cattermole wrote:
> On 30/05/2015 11:46 p.m., short2cave wrote:
>> Consider this struct:
>>
>> ---
>> Foo
>> {
>>     uint a,b,c;
>>     float d,e,f;
>> }
>> ---
>>
>> in a collection:
>>
>> ---
>> Foo[] foos;
>> ---
>>
>> Looping a particular member is not cache friendly
>>
>> ---
>> foreach(foo;foos){/*foo.a = ...*/}
>> ---
>>
>> but to write clear, understable, structured code, the struct 
>> is necessary.
>>
>> So, is it possible to imagine an abstraction such as
>>
>> ---
>> FooData
>> {
>>     uint[] a,b,c;
>>     float[] d,e,f;
>>     Foo[] items(){}
>> }
>> ---
>>
>> that would allow to loop over the data in a cache-friendly way 
>> ?
>> You think that an item as the member but they are actually 
>> stored using
>> another memory layout ?
>>
>> A template for this would be particularly usefull:
>>
>> template DataFriendlyStruct(T) if (is(T==struct) && isPOD!T)
>> {
>>    alias DataFriendlyStruct = ...
>> }
>
> What exactly are you doing that such a micro optimization is 
> necessary?

It's just that i try to concrectly apply some things read in a 
paper a few monthes ago. I won't be able to find the link again 
but the idea is simple, here is a short summary:

>structured types are dead, people gotta stup using classes and 
>structs. >They're not efficient.

That's not a scoop. Programs are slow because of that but struct 
and class allow a complexity in the design that you can't reach 
with globals.

The problem if you have global declarations of data everywhere 
things become quickly super heavy, for example:

---
float[] effect1_filter_1_omega;
float[] effect1_filter_2_omega;
float[] effect2_filter_1_omega;
float[] effect2_filter_2_omega;
float[] voice1_osc1_phasemod_source1
float[] voice1_osc2_phasemod_source2
float[] voice2_osc1_phasemod_source1
float[] voice2_osc2_phasemod_source2
---

efficient to loop but imagine that we talking about 8 
oscillators, 32 voices per oscillator, 2 effects per voice, etc...

so an abstraction is required to give a 
"pseudo-structured-interface".