Add a developer mode

Briefcase installs the platform requirements defined in the setup.py file.

For someone using briefcase-template, for example, this means that it will pip install into the $PLATFORM/app_packages directory the packages defined in the setup.py.

It would be nice to have a “platform developer mode”, which would use a local version of those packages (specially useful for someone working on Toga).

One idea to implement this would be to provide a way of configuring alternative local versions for the requirements there, e.g.:

python setup.py TARGET --overrides package-overrides.json

And then, package-overrides.json could have something like:

{
    "toga": "/home/elias/src/toga/src/core/",
    "toga-android": "/home/elias/src/toga/src/android/"
}

This information would then be used by the install_platform_requirements function to feed pip the package names with the overrides applied.

[freakboy3742]

Or… even better… don’t symlink - pass in the local directory to the pip install process.

[freakboy3742]

The 0.3 branch now includes a developer mode.