multiple package source

[asmodehn]

When a package depends on another package for which the version is available in the same workspace, catkin_pure_python should do something to avoid pip errors (local version/remote version conflicts)...

[asmodehn]

This is already possible leveraging the requirements.txt file of your package.
requirements are installed with different option than the package.

So your requirements file could contain :

# To divert/prevent uninstalling attempt from a dependencies' dependency
# since pip requirements install is ignoring already installed packages for catkin_pure_python
# and these will be seen before by the installer for your dependency
futures
tornado

# adds dependency packages for development only
-e git+https://github.com/asmodehn/pyros-setup.git@config_refactor#egg=pyros_setup
-e git+https://github.com/asmodehn/pyros.git@config_refactor#egg=pyros

One can now realize that part of its workspace is defined by requirements, and part by wstools.
It s up to him to not have these collide.

TODO : Document that...

[asmodehn]

Note that pip may have his own issues around this feature.

Currently we are relying on pip feature to download dependencies when installing the package (via setup.py) if necessary. Since pip will write into the same prefix, it should deal with already installed depedencies properly.

We should be aware of the --ignore-installed option used in many places however, since it is used to avoid problems with the system packages (using prefix might cause some) and the packages installed in the workspace.

Things might change when we move to use --target instead of --prefix because of #58, since the --target option doesn't deal with PYTHONPATH in the same way then --prefix