Hi Khem, Paul I understand now.
Thank you both for your answers! - Davis On Tue, Oct 18, 2016 at 10:00 PM, Paul Eggleton < paul.eggle...@linux.intel.com> wrote: > Hi Davis, > > On Tue, 18 Oct 2016 18:37:50 Davis Roman wrote: > > I'm a yocto newbie and so I'm becoming familiar with the documentation. > > > > I came across a bitbake feature that is somewhat confusing to me > regarding > > the difference between optional/required inclusion versus inheritance. > > > > As far as optional/required inclusion is concerned, the documentation > > states quite clearly that the main difference is that the former will not > > issue an error message if the specified file is not found while the > latter > > will so there is no issue here. > > > > My issue has to do with the 'inherit' command. Sounds to me like > 'include' > > and 'require' already do the trick so I'm curious to know what value does > > 'inherit' bring ? > > The answer is that they are very similar - but tend to be used for slightly > different purposes. inherit is for where you have some functionality that > you > expect to be applicable across a number of recipes, so it should show up > in a > standard location in a reasonably standard format. The technical > differences > really stem from that: > > * Classes must appear in a classes subdirectory somewhere along BBPATH > * Classes must be named <something>.bbclass > * Classes can use EXPORT_FUNCTIONS so you can still call the original > function > from your overridden version > * It's easy to query from python code whether a recipe inherits a class > (and > it's something we do in quite a number of places); it's technically > possible > to do the same for include/require but more difficult > > include/require are much more generic and applicable for any other kind of > shared or encapsulated functionality or configuration that doesn't suit a > .bbclass. > > Note that not all classes are typically inherited from individual recipes > with > inherit - there are classes that are usually applied globally by adding > their > names to INHERIT (e.g. buildhistory). > > Hope that helps. > > Cheers, > Paul > > -- > > Paul Eggleton > Intel Open Source Technology Centre >
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