Lasse Kärkkäinen wrote:
Here's an updated version of the C++ wrapper that I posted earlier in September 2007. I would like this to be included in the ALSA distribution after some peer review.
Yes, an ALSA C++ wrapper is a good idea.
error(std::string const& function, int err): std::runtime_error("ALSA " + function + " failed: " + std::string(snd_strerror(err))), err(err) {}
I'm not sure that including the function name and all parameters as they appear in the source file in the error message is a good idea; I wouldn't want to impose this policy on all applications using this header.
pcm(char const* device = "default", snd_pcm_stream_t stream = SND_PCM_STREAM_PLAYBACK, int mode = 0) {
This looks too much like a default constructor. I think neither device nor stream should have a default value.
ALSA_HPP_CLASS& set_##name(...) { ...; return *this; }\
Is there a reason why you return the object itself? Usually, returning an object implies that that object is a _different_ object with the setting applied, which would mean that the original object was _not_ changed, but that isn't true here.
class hw_config: internal::noncopyable {
Why should this object not be copyable?
And why do you have two different objects (*w_params and *w_config) for wrapping the hardware/software parameters?
hw_config(snd_pcm_t* pcm): pcm(pcm) { try { current(); } catch (std::runtime_error&) { any(); }
I don't like using exceptions when there's nothing wrong. Besides, getting the current parameters may fail due to other errors (like device unplugged).
I think it would be better if this object doesn't have a public constructor, and you would be able to create one only through a pcm object, like "hw_config c = pcm.any_hw_params();".
~mmap() { // We just assume that this works (can't do anything sensible if it fails). snd_pcm_mmap_commit(pcm, offset, frames);
This is the place where all the usual write errors must be checked. This cannot be done in a destructor. I think using RAII for the non- error commit just isn't possible.
Regards, Clemens