f-strings everywhere (#334)

* f-strings everywhere

starlette/authentication.py

@@ -28,7 +28,7 @@ def requires(
             if parameter.name == "request":
                 break
         else:
-            raise Exception('No "request" argument on function "%s"' % func)
+            raise Exception(f'No "request" argument on function "{func}"')
 
         if asyncio.iscoroutinefunction(func):
 

starlette/config.py

@@ -23,16 +23,14 @@ class Environ(MutableMapping):
     def __setitem__(self, key: typing.Any, value: typing.Any) -> None:
         if key in self._has_been_read:
             raise EnvironError(
-                "Attempting to set environ['%s'], but the value has already be read."
-                % key
+                f"Attempting to set environ['{key}'], but the value has already be read."
             )
         self._environ.__setitem__(key, value)
 
     def __delitem__(self, key: typing.Any) -> None:
         if key in self._has_been_read:
             raise EnvironError(
-                "Attempting to delete environ['%s'], but the value has already be read."
-                % key
+                f"Attempting to delete environ['{key}'], but the value has already be read."
             )
         self._environ.__delitem__(key)
 
@@ -71,7 +69,7 @@ class Config:
             return self._perform_cast(key, value, cast)
         if default is not undefined:
             return self._perform_cast(key, default, cast)
-        raise KeyError("Config '%s' is missing, and has no default." % key)
+        raise KeyError(f"Config '{key}' is missing, and has no default.")
 
     def _read_file(self, file_name: str) -> typing.Dict[str, str]:
         file_values = {}  # type: typing.Dict[str, str]
@@ -95,13 +93,12 @@ class Config:
             value = value.lower()
             if value not in mapping:
                 raise ValueError(
-                    "Config '%s' has value '%s'. Not a valid bool." % (key, value)
+                    f"Config '{key}' has value '{value}'. Not a valid bool."
                 )
             return mapping[value]
         try:
             return cast(value)
         except (TypeError, ValueError) as exc:
             raise ValueError(
-                "Config '%s' has value '%s'. Not a valid %s."
-                % (key, value, cast.__name__)
+                f"Config '{key}' has value '{value}'. Not a valid {cast.__name__}."
             )

starlette/datastructures.py

@@ -28,16 +28,16 @@ class URL:
                     break
 
             if host_header is not None:
-                url = "%s://%s%s" % (scheme, host_header, path)
+                url = f"{scheme}://{host_header}{path}"
             elif server is None:
                 url = path
             else:
                 host, port = server
                 default_port = {"http": 80, "https": 443, "ws": 80, "wss": 443}[scheme]
                 if port == default_port:
-                    url = "%s://%s%s" % (scheme, host, path)
+                    url = f"{scheme}://{host}{path}"
                 else:
-                    url = "%s://%s:%s%s" % (scheme, host, port, path)
+                    url = f"{scheme}://{host}:{port}{path}"
 
             if query_string:
                 url += "?" + query_string.decode()
@@ -111,12 +111,12 @@ class URL:
 
             netloc = hostname
             if port is not None:
-                netloc += ":%d" % port
+                netloc += f":{port}"
             if username is not None:
                 userpass = username
                 if password is not None:
-                    userpass += ":%s" % password
-                netloc = "%s@%s" % (userpass, netloc)
+                    userpass += f":{password}"
+                netloc = f"{userpass}@{netloc}"
 
             kwargs["netloc"] = netloc
 
@@ -133,7 +133,7 @@ class URL:
         url = str(self)
         if self.password:
             url = str(self.replace(password="********"))
-        return "%s(%s)" % (self.__class__.__name__, repr(url))
+        return f"{self.__class__.__name__}({repr(url)})"
 
 
 class DatabaseURL(URL):
@@ -191,7 +191,7 @@ class Secret:
         self._value = value
 
     def __repr__(self) -> str:
-        return "%s('**********')" % self.__class__.__name__
+        return f"{self.__class__.__name__}('**********')"
 
     def __str__(self) -> str:
         return self._value
@@ -218,7 +218,7 @@ class CommaSeparatedStrings(Sequence):
 
     def __repr__(self) -> str:
         list_repr = repr([item for item in self])
-        return "%s(%s)" % (self.__class__.__name__, list_repr)
+        return f"{self.__class__.__name__}({list_repr})"
 
     def __str__(self) -> str:
         return ", ".join([repr(item) for item in self])
@@ -294,7 +294,7 @@ class QueryParams(typing.Mapping[str, str]):
         return urlencode(self._list)
 
     def __repr__(self) -> str:
-        return "%s(query_string=%s)" % (self.__class__.__name__, repr(str(self)))
+        return f"{self.__class__.__name__}(query_string={repr(str(self))})"
 
 
 class Headers(typing.Mapping[str, str]):
@@ -383,8 +383,8 @@ class Headers(typing.Mapping[str, str]):
     def __repr__(self) -> str:
         as_dict = dict(self.items())
         if len(as_dict) == len(self):
-            return "%s(%s)" % (self.__class__.__name__, repr(as_dict))
-        return "%s(raw=%s)" % (self.__class__.__name__, repr(self.raw))
+            return f"{self.__class__.__name__}({repr(as_dict)})"
+        return f"{self.__class__.__name__}(raw={repr(self.raw)})"
 
 
 class MutableHeaders(Headers):

starlette/middleware/wsgi.py

@@ -16,7 +16,7 @@ def build_environ(scope: Scope, body: bytes) -> dict:
         "SCRIPT_NAME": "",
         "PATH_INFO": scope["path"],
         "QUERY_STRING": scope["query_string"].decode("ascii"),
-        "SERVER_PROTOCOL": "HTTP/%s" % scope["http_version"],
+        "SERVER_PROTOCOL": f"HTTP/{scope['http_version']}",
         "wsgi.version": (1, 0),
         "wsgi.url_scheme": scope.get("scheme", "http"),
         "wsgi.input": io.BytesIO(body),
@@ -43,7 +43,7 @@ def build_environ(scope: Scope, body: bytes) -> dict:
         elif name == "content-type":
             corrected_name = "CONTENT_TYPE"
         else:
-            corrected_name = "HTTP_%s" % name.upper().replace("-", "_")
+            corrected_name = f"HTTP_{name}".upper().replace("-", "_")
         # HTTPbis say only ASCII chars are allowed in headers, but we latin1 just in case
         value = value.decode("latin1")
         if corrected_name in environ:

starlette/routing.py

@@ -103,13 +103,13 @@ def compile_path(
     for match in PARAM_REGEX.finditer(path):
         param_name, convertor_type = match.groups("str")
         convertor_type = convertor_type.lstrip(":")
-        assert convertor_type in CONVERTOR_TYPES, (
-            "Unknown path convertor '%s'" % convertor_type
-        )
+        assert (
+            convertor_type in CONVERTOR_TYPES
+        ), f"Unknown path convertor '{convertor_type}'"
         convertor = CONVERTOR_TYPES[convertor_type]
 
         path_regex += path[idx : match.start()]
-        path_regex += "(?P<%s>%s)" % (param_name, convertor.regex)
+        path_regex += f"(?P<{param_name}>{convertor.regex})"
 
         path_format += path[idx : match.start()]
         path_format += "{%s}" % param_name
@@ -146,7 +146,7 @@ class Route(BaseRoute):
         *,
         methods: typing.List[str] = None,
         name: str = None,
-        include_in_schema: bool = True
+        include_in_schema: bool = True,
     ) -> None:
         assert path.startswith("/"), "Routed paths must start with '/'"
         self.path = path

starlette/staticfiles.py

@@ -22,7 +22,7 @@ NOT_MODIFIED_HEADERS = (
 class StaticFiles:
     def __init__(self, *, directory: str, check_dir: bool = True) -> None:
         if check_dir and not os.path.isdir(directory):
-            raise RuntimeError("Directory '%s' does not exist" % directory)
+            raise RuntimeError(f"Directory '{directory}' does not exist")
         self.directory = directory
         self.config_checked = False
 
@@ -58,9 +58,9 @@ class _StaticFilesResponder:
         try:
             stat_result = await aio_stat(directory)
         except FileNotFoundError:
-            raise RuntimeError("StaticFiles directory '%s' does not exist." % directory)
+            raise RuntimeError(f"StaticFiles directory '{directory}' does not exist.")
         if not (stat.S_ISDIR(stat_result.st_mode) or stat.S_ISLNK(stat_result.st_mode)):
-            raise RuntimeError("StaticFiles path '%s' is not a directory." % directory)
+            raise RuntimeError(f"StaticFiles path '{directory}' is not a directory.")
 
     def is_not_modified(self, stat_headers: typing.Dict[str, str]) -> bool:
         etag = stat_headers["etag"]

starlette/testclient.py

@@ -86,7 +86,7 @@ class _ASGIAdapter(requests.adapters.HTTPAdapter):
         elif port == default_port:
             headers = [(b"host", host.encode())]
         else:
-            headers = [(b"host", ("%s:%d" % (host, port)).encode())]
+            headers = [(b"host", (f"{host}:{port}").encode())]
 
         # Include other request headers.
         headers += [

tests/test_applications.py

@@ -70,7 +70,7 @@ def all_users_page(request):
 @users.route("/{username}")
 def user_page(request):
     username = request.path_params["username"]
-    return PlainTextResponse("Hello, %s!" % username)
+    return PlainTextResponse(f"Hello, {username}!")
 
 
 app.mount("/users", users)

tests/test_responses.py

@@ -255,7 +255,7 @@ def test_template_response():
                 self.name = name
 
             def render(self, context):
-                return "username: %s" % context["username"]
+                return f"username: {context['username']}"
 
         async def asgi(receive, send):
             template = Template("index.html")

tests/test_routing.py

@@ -90,7 +90,7 @@ async def websocket_endpoint(session):
 @app.websocket_route("/ws/{room}")
 async def websocket_params(session):
     await session.accept()
-    await session.send_text("Hello, %s!" % session.path_params["room"])
+    await session.send_text(f"Hello, {session.path_params['room']}!")
     await session.close()
 
 
@@ -208,7 +208,7 @@ def test_router_add_websocket_route():
 
 def http_endpoint(request):
     url = request.url_for("http_endpoint")
-    return Response("URL: %s" % url, media_type="text/plain")
+    return Response(f"URL: {url}", media_type="text/plain")
 
 
 class WebsocketEndpoint: