Prevent creating empty .ropeproject with null conf

[karimbenbourenane]

When ropeFolder is defined in the configuration but set to null (as would happen with a default config generated by e.g. Zed editing a python file), avoid creating an empty and unused .ropeproject directory. This change completes what I think was the goal of https://github.com/python-lsp/python-lsp-server/pull/604/files, where "ropeFolder": null in the configuration still generates an empty and unused .ropeproject folder.

[ccordoba12]

Hey @karimbenbourenane, thanks for your contribution! I have a quick question for you: how is this different from #604?

Also, pinging @osiewicz about this (the author of #604). What do you think about this one?

[osiewicz]

I sketched up a quick example of playground, but I feel like that'd regress us to before #604 (where you wouldn't be able to pass in null?)?
https://www.online-python.com/Qg4WIZrYfk
I guess the bug might be in Zed and not in pylsp.

[karimbenbourenane]

Hey @karimbenbourenane, thanks for your contribution! I have a quick question for you: how is this different from #604?

Also, pinging @osiewicz about this (the author of #604). What do you think about this one?

It's different in that, the default configuration with zed will be "ropeFolder": null. In #604, this means that despite an explicitly stated null ropeFolder, it will generate an empty and unused .ropeproject directory any time the pylsp is used for example editing a python file. The change I submitted does not do that.

[karimbenbourenane]

@ccordoba12 see the case where rope_config = {"ropeFolder": None}

In #604 the condition passes and the .ropeproject ends up getting generated anyway because of Project(self._root_path, ropefolder=None) being executed. In this proposed change (#664) None does not get passed as a named argument for ropeFolder when "ropeFolder" is a key in the rope_config with value set to None.

[osiewicz]

We do want to pass in None as a ropefolder argument though, as that's what disables creation of a Rope cache.. Please see: https://github.com/python-rope/rope/blob/a32584f5742c093b10437f8da13bfefddb19c155/rope/base/project.py#L260 and the constructor:
https://github.com/python-rope/rope/blob/a32584f5742c093b10437f8da13bfefddb19c155/rope/base/project.py#L198C45-L198C55
https://github.com/python-rope/rope/blob/a32584f5742c093b10437f8da13bfefddb19c155/rope/base/project.py#L227
https://github.com/python-rope/rope/blob/a32584f5742c093b10437f8da13bfefddb19c155/rope/base/project.py#L259

[AdamOlczak]

@osiewicz I've done some digging into this issue and while I can confirm the issue exists here in pylsp, I don't agree with the proposed reason and solution for this issue by @karimbenbourenane.

As you mentioned and tested by you, it would probably regress to before #604.

I did test it and it seems that when the rope_config is being accessed in _rope_project_builder it doesn't have ropeFolder key at all, only the plugins

python-lsp-server/pylsp/workspace.py

Line 80 in 89265cd

rope_folder = rope_config.get("ropeFolder")

Tracing it back to where the settings are being updated I found that Config.settings method returns incorrect settings object.
Specifically this line:

python-lsp-server/pylsp/config/config.py

Lines 149 to 150 in 89265cd

	# LSP configuration
	settings = _utils.merge_dicts(settings, self._settings)

_settings dict contains correct configuration as requested by the LSP client, with ropeFolder: None, however call to _utils.merge_dicts returns the dict without ropeFolder causing an issue.

To confirm this, I've logged the value using this snippet:

        # LSP configuration
        log.debug(f"{settings=}")
        log.debug(f"{self._settings=}")
        settings = _utils.merge_dicts(settings, self._settings)
        log.debug(f"{settings=}")

giving me the following result:

2025-09-05 00:24:12,887 CEST - DEBUG - pylsp.config.config - settings={'plugins': {'flake8': {'enabled': False}, 'pylint': {'enabled': False, 'args': [], 'executable': None}, 'rope_autoimport': {'enabled': False, 'memory': False, 'completions': {'enabled': True}, 'code_actions': {'enabled': True}}, 'pydocstyle': {'enabled': False}, 'preload': {'modules': ['OpenGL', 'PIL', 'array', 'audioop', 'binascii', 'cPickle', 'cStringIO', 'cmath', 'collections', 'datetime', 'errno', 'exceptions', 'gc', 'imageop', 'imp', 'itertools', 'marshal', 'math', 'matplotlib', 'mmap', 'mpmath', 'msvcrt', 'networkx', 'nose', 'nt', 'numpy', 'operator', 'os', 'os.path', 'pandas', 'parser', 'rgbimg', 'scipy', 'signal', 'skimage', 'sklearn', 'statsmodels', 'strop', 'sympy', 'sys', 'thread', 'time', 'wx', 'xxsubtype', 'zipimport', 'zlib']}, 'pylsp_mypy': {}, 'rope_completion': {'enabled': False, 'eager': False}}, 'rope': {'extensionModules': ['OpenGL', 'PIL', 'array', 'audioop', 'binascii', 'cPickle', 'cStringIO', 'cmath', 'collections', 'datetime', 'errno', 'exceptions', 'gc', 'imageop', 'imp', 'itertools', 'marshal', 'math', 'matplotlib', 'mmap', 'mpmath', 'msvcrt', 'networkx', 'nose', 'nt', 'numpy', 'operator', 'os', 'os.path', 'pandas', 'parser', 'rgbimg', 'scipy', 'signal', 'skimage', 'sklearn', 'statsmodels', 'strop', 'sympy', 'sys', 'thread', 'time', 'wx', 'xxsubtype', 'zipimport', 'zlib']}}
2025-09-05 00:24:12,887 CEST - DEBUG - pylsp.config.config - self._settings={'plugins': {'pycodestyle': {'enabled': False}, 'rope_autoimport': {'enabled': True, 'memory': True}, 'pylsp_mypy': {'enabled': False, 'overrides': ['--python-executable', '/nix/store/v72ywdz0dd2d6sb3knymx9ww8r6pcqba-python3-3.13.5/bin/python', '--cache-dir=/dev/null', True]}, 'jedi': {'environment': '/nix/store/v72ywdz0dd2d6sb3knymx9ww8r6pcqba-python3-3.13.5/bin/python'}}, 'rope': {'ropeFolder': None}}
2025-09-05 00:24:12,887 CEST - DEBUG - pylsp.config.config - settings={'plugins': {'flake8': {'enabled': False}, 'pycodestyle': {'enabled': False}, 'pylint': {'enabled': False, 'args': [], 'executable': None}, 'jedi': {'environment': '/nix/store/v72ywdz0dd2d6sb3knymx9ww8r6pcqba-python3-3.13.5/bin/python'}, 'rope_completion': {'enabled': False, 'eager': False}, 'rope_autoimport': {'memory': True, 'code_actions': {'enabled': True}, 'enabled': True, 'completions': {'enabled': True}}, 'pydocstyle': {'enabled': False}, 'preload': {'modules': ['OpenGL', 'PIL', 'array', 'audioop', 'binascii', 'cPickle', 'cStringIO', 'cmath', 'collections', 'datetime', 'errno', 'exceptions', 'gc', 'imageop', 'imp', 'itertools', 'marshal', 'math', 'matplotlib', 'mmap', 'mpmath', 'msvcrt', 'networkx', 'nose', 'nt', 'numpy', 'operator', 'os', 'os.path', 'pandas', 'parser', 'rgbimg', 'scipy', 'signal', 'skimage', 'sklearn', 'statsmodels', 'strop', 'sympy', 'sys', 'thread', 'time', 'wx', 'xxsubtype', 'zipimport', 'zlib']}, 'pylsp_mypy': {'overrides': ['--python-executable', '/nix/store/v72ywdz0dd2d6sb3knymx9ww8r6pcqba-python3-3.13.5/bin/python', '--cache-dir=/dev/null', True], 'enabled': False}}, 'rope': {'extensionModules': ['OpenGL', 'PIL', 'array', 'audioop', 'binascii', 'cPickle', 'cStringIO', 'cmath', 'collections', 'datetime', 'errno', 'exceptions', 'gc', 'imageop', 'imp', 'itertools', 'marshal', 'math', 'matplotlib', 'mmap', 'mpmath', 'msvcrt', 'networkx', 'nose', 'nt', 'numpy', 'operator', 'os', 'os.path', 'pandas', 'parser', 'rgbimg', 'scipy', 'signal', 'skimage', 'sklearn', 'statsmodels', 'strop', 'sympy', 'sys', 'thread', 'time', 'wx', 'xxsubtype', 'zipimport', 'zlib']}}

I didn't investigate, as of now, why merge_dicts is returning the new dict as it is. It's too late for me to do that today.