The cppyy module is a frontend that requires an intermediate (Python interpreter dependent) layer, and a backend (see Package Structure). Because of this layering and because it leverages several existing packages through reuse, the relevant codes are contained across a number of repositories.

The backend repo contains both the cppyy-cling (under “cling”) and cppyy-backend (under “clingwrapper”) packages.


Except for cppyy-cling, the structure in the repositories follows a normal PyPA package and they are thus are ready to build with setuptools: simply checkout the package and either run python, or use pip. It is highly recommended to follow the dependency chain when manually upgrading packages individually (i.e. cppyy-cling, cppyy-backend, CPyCppyy if on CPython, and then finally cppyy).

As an example, to upgrade CPyCppyy to the latest version in the repository, do:

$ git clone
$ pip install ./CPyCppyy --upgrade

Installation of the cppyy package works the same way (just replace “CPyCppyy” with “cppyy”). Please see the pip documentation for more options, such as developer mode.

For the clingwrapper part of the backend (package “cppyy-backend”), which lives in a subdirectory in the cppyy-backend repository, do:

$ git clone
$ pip install ./cppyy-backend/clingwrapper --upgrade

Finally, the cppyy-cling package (subdirectory “cling”) requires sources being pulled in from upstream, and thus takes a few extra steps:

$ git clone
$ cd cppyy-backend/cling
$ python egg_info
$ python
$ pip install . --upgrade

The egg_info command is needed for to find the right version. It in turn downloads the proper release from upstream, trims and patches it, and installs the result in the “src” directory. When done, the structure of cppyy-cling looks again like a PyPA package and can be used as expected.