Microsoft Python Language Server
Microsoft Python Language Server implements the Language Server Protocol.
Feel free to file issues or ask questions on our issue tracker, and we welcome code contributions.
Build/contributing instructions
Troubleshooting and known issues
Linting options (diagnostics)
The language server implements diagnostics (or linting), which runs on user code.
The following diagnostics are supported:
Code
Description
inherit-non-class
Attempted to inherit something that is not a class.
too-many-function-arguments
Too many arguments have been provided to a function call.
too-many-positional-arguments-before-star
Too many arguments have been provided before a starred argument.
no-cls-argument
First parameter in a class method must be cls
no-method-argument
Method has no arguments
no-self-argument
First parameter in a method must be self
parameter-already-specified
A argument with this name has already been specified.
parameter-missing
A required positional argument is missing.
positional-argument-after-keyword
A positional argument has been provided after a keyword argument.
positional-only-named
A positional-only argument (3.8+) has been named in a function call.
return-in-init
Encountered an explicit return in __init__ function.
typing-generic-arguments
An error occurred while constructing Generic.
typing-newtype-arguments
An error occurred while constructing NewType.
typing-typevar-arguments
An error occurred while constructing TypeVar.
unknown-parameter-name
The keyword argument name provided is unknown.
unresolved-import
An import cannot be resolved, and may be missing.
undefined-variable
A variable has been used that has not yet been defined.
variable-not-defined-globally
A variable is not defined in the global scope.
variable-not-defined-nonlocal
A variable is not defined in non-local scopes.
Linting can be controlled via the user configuration. In VS Code, this is settings.json, but other
clients would send this via workspace/didChangeConfiguration.
If python.linting.enabled is set to false in the user configuration, then no diagnostics
will be collected other than syntax errors and unresolved imports.
To control the visibility and severity of the diagnotics, there are a number of lists
that can be set in the user configuration which make use of each diagnostic's error code.
Setting
Description
python.analysis.errors
Diagnostics which should be shown as errors.
python.analysis.warnings
Diagnostics which should be shown as warnings.
python.analysis.information
Diagnostics which should be shown as informational.
python.analysis.disabled
Diagnotics which should not be shown at all.
An example of a user configuration which sets these options:
{
"python.analysis.errors":["undefined-variable"],
"python.analysis.warnings":["unknown-parameter-name"],
"python.analysis.information":["unresolved-import"],
"python.analysis.disabled":["too-many-function-arguments","parameter-missing"],
}
Linting can also be controlled on an invidual line basis with a generalized #noqa. Lines with #noqa will have their diagnostic output suppressed.
An example usage:
from python import language_server # noqa will suppress the linting message for this line
Cache location
During analysis language server produces Python code from compiled modules and builtins which is similar to Python module stubs.
It may also produce database files holding module analysis for faster retrieval later. Cache location is at
Windows
"%LOCALAPPDATA%\Microsoft\Python Language Server" (which is Environment.SpecialFolder.LocalApplicationData). Typically "C:\Users\\%USER_NAME%\AppData\Local\Microsoft\Python Language Server"
Linux
"$XDG_CACHE_HOME/Microsoft/Python Language Server", or if XDG_CACHE_HOME is not set, "$HOME/.cache/Microsoft/Python Language Server"
macOS
"$HOME/Library/Caches/Microsoft/Python Language Server"