Subject: Re: [ecasound] MISC: Of dump-commands
From: janne halttunen (jhalttun@pp.htv.fi)
Date: Fri Oct 27 2000 - 16:25:11 EEST
> > The dump-commands have been useful in my ecasound-frontend at
> > reducing the parsing of ecasound normal output. You have to, however,
> > to request the dumping, there's no automatic 'when value changes'
> > dump-objects. I don't know if it would be worth the effort to extend
> > the dump section with commands like: dump-object-add
> > <value-to-dump-when-changed>, or to have multiple dump-targets.
> [...]
> > Depends on you Kai, but I guess at some point it would be easier
> > to go straight to libecasound. How is it going with the C-api? :)
>
> The C-api is still in the "might-be-implemented" section. But unlike many
> other todo-items, I'm willing to give this top priority. I'm just still
> unsure whether C-API is good enough. As you might have noticed, I'd like
> to get more people involved in ecasound development (either ecasound
> itself, or apps using ecasound/libecasound). There are so many things I'd
> like to try, but I just don't have the time. I've tried to make the C++
> API as usable as possible, but this hasn't received much interest. So
> far, extending the console mode API, and providing LADSPA support have
> proven to be most useful. But what to do now...
>
> Possible solutions:
> 1) continue to extend the iactive-mode
> 2) provide a small C-API (easy to maintain)
> 3) provide a more functional C-API (C wrapper for C++)
> 4) provide wrappers for scripting languages (Python, Perl, ?)
The problem I had with the C++ API was that when I tried (sometime ago) to make Python-bindings for it with SWIG, (Simplified Wrapper and Interface Generator) it
spewed out too many error-messages to even begin with. I learned that SWIG was most suitable for binding C-stuff.
While I was exploring the possibility of a Qt-ui for Heteca, I found that there's one bindings-generator that's specifically made for C++ and Python, called SIP.
(the PyQT/PyKDE bindings are done with it)
I haven't been able to compile it yet, (probably due missing -devel packets) but so far it seems promising. ;)
http://www.thekompany.com/projects/pykde/background.php3?dhtml_ok=1
SWIG, on the other hand has support for multiple scripting languages. (including Perl) There supposedly are some plans to expand the C++ support in future
versions.
> I have little experience with the above mentioned "scripting" languages,
> so it's difficult for me to compare the alternatives. Writing a simple
> C-API (2) would be a quick task, but I'd like to know what functionality
> is needed to do actually do something useful. Here's a short example:
>
> --cut--
> How does this look? Implementing the above would be really an easy a task,
> but as you imagine, it can quickly turn into a maintainance hell.
> Thoughts; what would be a good subset of libecasound functionality?
The main thing in my mind is quick access (minimal/no parsing) to ecasound variables, like: engine status, aio-positions and cop-values. The dump-commands help,
but I'm thinking the position-slider should rather be sliding than jumping. :)
I think that it could be achieved either by instant access to the variables (through some sort of bindings), or (in iactive-mode) automatic value dumping with
adjustable intervals to dedicated dump-targets. The first one is perhaps more reasonable, since in dumping there's always the conversion from string to int, which
slows things down.
jsh
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