[alsa-devel] [PATCH] ascenario: Add scenario support to alsa-lib
perex at perex.cz
Wed Oct 7 11:47:19 CEST 2009
On Wed, 7 Oct 2009, Takashi Iwai wrote:
>> But regarding goto, I'm really stuck. We can add some block control:
>> BEGIN="" .. END="" (looks like a goto anyway)
> Hm, still not much improvement, indeed.
>> Or skip some lines:
> Oh, no! I don't want to debug a DSP assembly :)
>> But these solutions do not bring much readability. Another possibility
>> (compromise) is to use a goto command to skip all lines to next label to
>> reduce usage of named labels (which is not a big fun at least in
>> init/default file):
>> It works without any code change in current parser.
> I'm afraid that udev config is way too simple for the conditionals.
There are plenty conditionals in udev configuration files. That was main
reason to use this syntax for alsactl.
> And we do need conditionals to handle many cases. XML can do better
> for such a purpose, but moving to XML now is another question...
Really better? XML is good for static data but not for non-linear
non-linear stuff and eventually modifies XML at runtime. We have similar
situation in alsa-lib. The syntax structure is changed at runtime
depending on external data. But it requires some system resources
Things why I chose udev-like syntax:
- well known "key operator value" syntax
- very easy to parse
- parser reads and executes code directly without storing the source
or portions to memory (really small memory usage)
- normal conditions are really small in syntax files
If only the goto command is major drawback, I can live with it.
We need to take account the useability and the implementation complexity.
I think a compromise is essential.
Jaroslav Kysela <perex at perex.cz>
Linux Kernel Sound Maintainer
ALSA Project, Red Hat, Inc.
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