On Tue, Nov 24, 2020 at 09:49:30AM +0100, Markus Armbruster wrote: > Eduardo Habkost <ehabk...@redhat.com> writes: > > > On Mon, Nov 23, 2020 at 08:51:27AM +0100, Markus Armbruster wrote: > >> Eduardo Habkost <ehabk...@redhat.com> writes: > >> > >> > On Fri, Nov 20, 2020 at 06:29:16AM +0100, Markus Armbruster wrote: > >> [...] > >> >> When the structure of a data type is to be kept away from its users, I > >> >> prefer to keep it out of the public header, so the compiler enforces the > >> >> encapsulation. > >> > > >> > I prefer that too, except that it is impossible when users of the > >> > API need the compiler to know the struct size. > >> > >> There are cases where the structure of a data type should be > >> encapsulated, yet its size must be made known for performance (avoid > >> dynamic memory allocation and pointer chasing). > >> > >> Need for encapsulation correlates with complex algorithms and data > >> structures. The cost of dynamic allocation is often in the noise then. > > > > I don't know what we are talking about anymore. None of this > > applies to the QNum API, right? > > > > QNum/QNumValue are not complex data structures, and the reason we > > need the compiler to know the size of QNumValue is not related to > > performance at all. > > We started with the question whether to make QNumValue's members > private. We digressed to the question when to make members private. > So back to the original question. > > > We might still want to discourage users of the QNum API from > > accessing QNum.u/QNumValue.u directly. Documenting the field as > > private is a very easy way to do it. > > It's a complete non-issue. QNum has been around for years, and we > haven't had any issues that could've been plausibly avoided by asking > people to refrain from accessing its members. > > If there was an actual need to keep the members private, I'd move the > struct out of the header, so the compiler enforces privacy.
Understood. There's still a question I'd like to answer, to decide how the API documentation should look like: Is QNum.u/QNumValue.u required to be part of the API documentation? If accessing that field directly is not necessary for using the API, I don't think it should appear in the documentation (because it would be just noise). -- Eduardo