flit provides an install option. I just wonder what is the difference between flit install --symlink and pip install --editable ., or more generally, flit install and pip install? Unfortunately the documentation is currently not clear about this at all:
Install the package on your system.
By default, the package is installed to the same Python environment that Flit itself is installed in; use --python or FLIT_INSTALL_PYTHON to override this.
If you don’t have permission to modify the environment (e.g. the system Python on Linux), Flit may do a user install instead. Use the --user or --env flags to force this one way or the other, rather than letting Flit guess.
They both seem to be doing the same thing, when should I use pip and when flit?