- mongocxx (v3)
- API and ABI versioning
API and ABI versioning
- We use semantic versioning.
- bsoncxx and mongocxx both define corresponding CMake variables for MAJOR, MINOR, and PATCH.
- Both bsoncxx and mongocxx both have a single scalar ABI version.
- Only bump ABI version on incompatible ABI change (not for ABI additions).
- We stay on ABI version _noabi (without bumping for incompatible changes) until ABI is stable.
Parallel Header Installation
- For mongocxx, install all headers to
- For bsoncxx, install all headers to
- We install a pkg-config file to shield consumers from this complexity.
Sonames and symlinks
Note that below examples are given for libmongocxx, but also apply to libbsoncxx
DSO = Dynamic Shared Object, to use Ulrich Drepper’s terminology
- Physical filename for a DSO is
Note that the physical filename is disconnected from ABI version/soname. This looks a bit strange, but allows multiple versions of the library with the same ABI version to be installed on the same system.
- soname for a DSO is
We provide a soname symlink that links to the physical DSO. We also provide a dev symlink that links to the soname symlink of the highest ABI version of the library installed.
- We provide inline namespace macros for both mongocxx and bsoncxx.
- This allows multiple, ABI incompatible versions of the library to be linked into the same application.
- The name of the namespace is
v$ABI. We create them from ABI version to maintain forwards compatibibility.
Occasionally we will phase features out of use in the driver. In the release that marks a feature as deprecated we offer several transition options:
- The original method, marked with
MONGOCXX_DEPRECATED. This will raise deprecation warnings when compiled.
- A variant of the feature suffixed with
_deprecated. This will require only small code changes and will not raise deprecation warnings.
- A new feature that provides alternate functionality. The new feature may not be a drop-in replacement for the deprecated feature and switching to it may require code changes. In the rare case where we remove a feature without replacing it, this third option will not be available.
In the following release, the original feature marked with
MONGOCXX_DEPRECATED and its
_deprecated equivalent will be removed.
// release 1 with a supported feature void do_thing(); // release 2 where the feature is deprecated in favor of a new feature MONGOCXX_DEPRECATED void do_thing(); void do_thing_deprecated(); void do_new_thing(); // release 3 where the original feature is removed void do_new_thing();
In the case of a feature rename we do not offer a suffixed
as one can simply switch to using the new name with the same amount of effort.
// release 1 with a supported feature void do_thing(); // release 2 where the feature name is renamed MONGOCXX_DEPRECATED void do_thing(); void do_stuff(); // release 3 where the original feature name is removed void do_stuff();