>From our last BseSong merge:
> There's one other thing I noticed during review. With the old GParamSpec +
> GObject based property API, the GObject machinery ensures that the GValue
> passed in to property setters complies with the GParamSpec value range. With
> our IDL API, nothing like that is enforced anymore. That means, an int32
> property between 1-256 can now be set to 0 or -2^31 through the API. For a
> denominator to become 0 that could affect stability.
Please keep that in mind for ported properties and watch out if we shouldn't
add extra guards, like:
>
> denominator = CLAMP (input, 0, 256)
I think it might be better to re-add range enforcement. Right now, I would have
to write this setter code:
```
void
SongImpl::denominator (int val)
{
BseSong *self = as<BseSong*>();
val = CLAMP (val, 1, 256);
if (int (self->denominator) != val)
{
const char *prop = "denominator";
push_property_undo (prop);
self->denominator = val <= 2 ? val : 1 << g_bit_storage (val - 1);
bse_song_update_tpsi_SL (self);
notify (prop);
}
}
```
Note that we duplicate the defaults here, which is not ideal. So we could also
check against the pspec, somewhat like
```
...
val = prop_denominator.clamp (val);
// prop_denominator would be generated and contains min(), max(), def(),
name()
...
```
But I think ultimately what I really want to write is this code:
```
void
SongImpl::denominator_impl (int val)
{
BseSong *self = as<BseSong*>();
self->denominator = val <= 2 ? val : 1 << g_bit_storage (val - 1);
bse_song_update_tpsi_SL (self);
}
```
and have the actual denominator (int val) function be generated automatically,
which should
- constrain val to param spec
- do nothing at all if val equals the value returned by the getter
- push undo if property has undo
- call the _impl function
- notify the property
Consider this a brianstorming idea I at least wanted to share. Maybe the actual
implementation will be a bit different, but I think the general idea to have
each setter always execute some steps at the beginning and some steps at the
end of setting a property is likely to make our actual code simpler.
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