On Fri, 03 May 2019 08:47:29 +0200,
Mark Brown wrote:
>
> > > > +#define cx2072x_plbk_eq_en_info snd_ctl_boolean_mono_info
>
> > > Why not just use the function directly rather than hiding it?
>
> > Just a standard idiom. Can be replaced if preferred.
>
> Please.
BTW, a good reason for the style above is that it makes code more
undrestandable. For defining a ctl element, typically we define three
callback functions, info, get and put, in that order:
static int foo_info()
{
....
}
static int foo_get()
{
....
}
static int foo_put()
{
...
};
and often the actual snd_kcontrol_new table containing these callbacks
appears much later, where you'd need to scroll down a few screens to
read that point.
In the above, especially defining the info callback at the beginning
is important. By reading foo_init() at first, readers can know which
type (int, boolean, enum, etc) and the number of elements to be used
in get/put callbacks beforehand. It's a commonly seen mistake, for
example, that a wrong type (e.g. integer) is passed to info callback
while enum type is used in the get/put.
The #define above keeps this foo_info() definition while optimizing
with the standard helper. If we drop this and set
snd_ctl_boolean_mono_info directly in the snd_kcontrol_new entry,
you'll have to go and back the screen just to take a look at the info
callback.
That's why I called it a standard idiom. It's not strictly necessary,
but often help reading / reviewing the code. Though, it's just
another bikeshed theme, so I'm not sticking with this style.
thanks,
Takashi
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