Re: [linux-audio-dev] CSL-0.1.2 Release

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Subject: Re: [linux-audio-dev] CSL-0.1.2 Release
From: Abramo Bagnara (abramo_AT_alsa-project.org)
Date: Thu Jun 07 2001 - 16:13:40 EEST

Paul Davis wrote:
>
> >> >Although I agree that many application don't need/want to cope with
> >> >hardware/software setting this is not a good reason to remove this
> >> >capability from API.
> >>
> >> If the API you're talking about is ALSA, then I totally agree with
> >> you. ALSA *is* a HAL, and its appropriate for it to contain these
> >> aspects in its design.
> >
> >ALSA is much more than a HAL as you already know: it's an API versatile
> >enough to talk *also* with hardware.
>
> Its design is 100% inspired by the operation of the hardware it can
> *also* talk to. It doesn't abstract that away at all.

I read from "abstract" definition:
"to consider apart from application to or association with a particular
instance"

I'd define "to abstract" as to find a model that can describe correctly
the underlying reality.

"Geometric shape" concept is an abstraction of "circle".

ALSA API *is* an abstraction suitable for PCM streams (hardware,
software, network oriented, etc.). Probably not the best doable (and I'm
very interested in improvements), but likely one of best available.

Your model describes a partial reality, a too partial reality in my
opinion.

>
> >This is exactly the key concept I'd like you note: "versatile enough".
> >
> >I insist that a right API need to have methods to get/set/query
> >properties for underlying objects.
>
> As long as we continue to promote such an API for use by standard
> audio applications, we will continue to waste people's time and make
> great steps forward more difficult.

Not if this part is not mandatory but used only when needed.

I explain better:
- an object has zero or more properties
- a property has a set of accepted values
- the object client may manipulate this set
- each object has a policy to choose for each property a value from its
current set

As you see:
- objects don't need to have properties
- clients are not forced to cope with properties (also if object has
some)

I hope to have undermined your stainless belief. 

-- 
Abramo Bagnara                       mailto:abramo_AT_alsa-project.org

Opera Unica                          Phone: +39.546.656023
Via Emilia Interna, 140
48014 Castel Bolognese (RA) - Italy

ALSA project               http://www.alsa-project.org
It sounds good!

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