S4Py is a tool and library for working with Sims 4 content. Right now it's fairly limited, but it will eventually do everything from low-level inspection of Sims4 data files to compiling a high-level description of what you want your mod to do from a single user-friendly input file into a package complete with automatically-generated string tables and SimData files (and checking to make sure that the tunables that you use are valid).

Because I've been developing software for a while now, I have fairly strong opinions about how builds should work. For example, the build tools should NEVER modify a file that you as a user directly edit; in fact, the output of a build step should never depend whether the output file existed before the build step executed, much less depend on its prior contents. This means that for the low-level build tool, if you maintain your assets as loose files in a directory and then run

s4py package assemble -o mymod.package sourcedir

mymod.package will contain ONLY the resources that were in sourcedir. (NOTE: the "package assemble" command doesn't exist yet)

Right now s4py is not going to be useful to you unless you want to do significant development work; it's in the very early stages of development. You can expect that there will be an XML-to-SimData compiler fairly soon; the assemble tool will follow fairly shortly after that. If there are any specific tools that you need, don't hesitate to let me know by filing a feature request.

All that s4py can do right now is list and extract the contents of a package.

First, make sure that you have Python 3.3 or above installed. Then, run

python setup.py install

If you want to work on s4py, I recommend instead running

python setup.py develop

Either way, you will then have the s4py binary available for use. Run it for further instructions.