Switch from pylint to flake8 for linting

.flake8

@@ -0,0 +1,8 @@
+[flake8]
+max-line-length = 100
+max-doc-length = 100
+extend-ignore =
+    # something == None constructs are needed for SQLAlchemy
+    E711
+per-file-ignores =
+    __init__.py: F401

.github/workflows/ci-tests.yml

@@ -103,12 +103,12 @@ jobs:
             - name: Install Python webservers
               run: pip3 install falcon starlette asgi_lifespan
 
-            - name: Install latest pylint
-              run: pip3 install -U pylint
+            - name: Install latest flake8
+              run: pip3 install -U flake8
               if: matrix.flavour == 'ubuntu-22'
 
             - name: Python linting
-              run: python3 -m pylint src
+              run: python3 -m flake8 src
               working-directory: Nominatim
               if: matrix.flavour == 'ubuntu-22'
 

CONTRIBUTING.md

@@ -60,10 +60,10 @@ are in process of consolidating the style. The following rules apply:
    * leave out space between a function name and bracket
      but add one between control statement(if, while, etc.) and bracket
 
-The coding style is enforced with pylint. It can be tested with:
+The coding style is enforced with flake8. It can be tested with:
 
 ```
-pylint3 --extension-pkg-whitelist=osmium nominatim
+make lint
 ```
 
 ## Testing

Makefile

@@ -24,7 +24,7 @@ pytest:
 	pytest test/python
 
 lint:
-	pylint src
+	flake8 src
 
 bdd:
 	cd test/bdd; behave -DREMOVE_TEMPLATE=1

docs/develop/Development-Environment.md

@@ -29,7 +29,7 @@ The Nominatim test suite consists of behavioural tests (using behave) and
 unit tests (using pytest). It has the following additional requirements:
 
 * [behave test framework](https://behave.readthedocs.io) >= 1.2.6
-* [Pylint](https://pylint.org/) (CI always runs the latest version from pip)
+* [flake8](https://flake8.pycqa.org/en/stable/) (CI always runs the latest version from pip)
 * [mypy](http://mypy-lang.org/) (plus typing information for external libs)
 * [Python Typing Extensions](https://github.com/python/typing_extensions) (for Python < 3.9)
 * [pytest](https://pytest.org)
@@ -55,7 +55,6 @@ the vendored version of osm2pgsql, you need to set the PATH accordingly.
 ### Installing prerequisites on Ubuntu/Debian
 
 The Python tools should always be run with the most recent version.
-In particular, pylint tends to have a lot of breaking changes between versions.
 The easiest way, to handle these Python dependencies is to run your
 development from within a virtual environment.
 
@@ -70,7 +69,7 @@ virtualenv ~/nominatim-dev-venv
 ~/nominatim-dev-venv/bin/pip install\
     psutil psycopg[binary] PyICU SQLAlchemy \
     python-dotenv jinja2 pyYAML datrie behave \
-    mkdocs mkdocstrings mkdocs-gen-files pytest pytest-asyncio pylint \
+    mkdocs mkdocstrings mkdocs-gen-files pytest pytest-asyncio flake8 \
     types-jinja2 types-markupsafe types-psutil types-psycopg2 \
     types-pygments types-pyyaml types-requests types-ujson \
     types-urllib3 typing-extensions unicorn falcon starlette \

src/nominatim_api/__init__.py

@@ -11,9 +11,6 @@
 import from this file, not from the source files directly.
 """
 
-# See also https://github.com/PyCQA/pylint/issues/6006
-# pylint: disable=useless-import-alias
-
 from .errors import (UsageError as UsageError)
 from .config import (Configuration as Configuration)
 

src/nominatim_api/config.py

@@ -8,5 +8,5 @@
 # This file is just a placeholder to make the config module available
 # during development. It will be replaced by nominatim_db/config.py on
 # installation.
-# pylint: skip-file
+# flake8: noqa
 from nominatim_db.config import *

src/nominatim_api/connection.py

@@ -21,6 +21,7 @@
 
 T = TypeVar('T')
 
+
 class SearchConnection:
     """ An extended SQLAlchemy connection class, that also contains
         the table definitions. The underlying asynchronous SQLAlchemy
@@ -32,37 +33,32 @@ def __init__(self, conn: AsyncConnection,
                  tables: SearchTables,
                  properties: Dict[str, Any]) -> None:
         self.connection = conn
-        self.t = tables # pylint: disable=invalid-name
+        self.t = tables
         self._property_cache = properties
         self._classtables: Optional[Set[str]] = None
         self.query_timeout: Optional[int] = None
 
-
     def set_query_timeout(self, timeout: Optional[int]) -> None:
         """ Set the timeout after which a query over this connection
             is cancelled.
         """
         self.query_timeout = timeout
 
-
     async def scalar(self, sql: sa.sql.base.Executable,
-                     params: Union[Mapping[str, Any], None] = None
-                    ) -> Any:
+                     params: Union[Mapping[str, Any], None] = None) -> Any:
         """ Execute a 'scalar()' query on the connection.
         """
         log().sql(self.connection, sql, params)
         return await asyncio.wait_for(self.connection.scalar(sql, params), self.query_timeout)
 
-
     async def execute(self, sql: 'sa.Executable',
                       params: Union[Mapping[str, Any], Sequence[Mapping[str, Any]], None] = None
-                     ) -> 'sa.Result[Any]':
+                      ) -> 'sa.Result[Any]':
         """ Execute a 'execute()' query on the connection.
         """
         log().sql(self.connection, sql, params)
         return await asyncio.wait_for(self.connection.execute(sql, params), self.query_timeout)
 
-
     async def get_property(self, name: str, cached: bool = True) -> str:
         """ Get a property from Nominatim's property table.
 
@@ -89,7 +85,6 @@ async def get_property(self, name: str, cached: bool = True) -> str:
 
         return cast(str, value)
 
-
     async def get_db_property(self, name: str) -> Any:
         """ Get a setting from the database. At the moment, only
             'server_version', the version of the database software, can
@@ -102,7 +97,6 @@ async def get_db_property(self, name: str) -> Any:
 
         return self._property_cache['DB:server_version']
 
-
     async def get_cached_value(self, group: str, name: str,
                                factory: Callable[[], Awaitable[T]]) -> T:
         """ Access the cache for this Nominatim instance.
@@ -125,7 +119,6 @@ async def get_cached_value(self, group: str, name: str,
 
         return value
 
-
     async def get_class_table(self, cls: str, typ: str) -> Optional[SaFromClause]:
         """ Lookup up if there is a classtype table for the given category
             and return a SQLAlchemy table for it, if it exists.