mypy: Centralize ViewFuncT definition into new file zerver/lib/types.py.

Originally was going to centralize this in zerver/lib/request.pyi, but this
file is not visible at run-time, being only a stub. The matching request.py
file seemed inappropriate, as it doesn't actually use ViewFuncT.

zerver/decorator.py

@@ -16,6 +16,7 @@ from zerver.lib.subdomains import get_subdomain, user_matches_subdomain
 from zerver.lib.timestamp import datetime_to_timestamp, timestamp_to_datetime
 from zerver.lib.utils import statsd, is_remote_server
 from zerver.lib.exceptions import RateLimited, JsonableError, ErrorCode
+from zerver.lib.types import ViewFuncT
 
 from zerver.lib.rate_limiter import incr_ratelimit, is_ratelimited, \
     api_calls_left, RateLimitedUser
@@ -42,7 +43,6 @@ else:
     get_remote_server_by_uuid = Mock()
     RemoteZulipServer = Mock()  # type: ignore # https://github.com/JukkaL/mypy/issues/1188
 
-ViewFuncT = TypeVar('ViewFuncT', bound=Callable[..., HttpResponse])
 ReturnT = TypeVar('ReturnT')
 
 webhook_logger = logging.getLogger("zulip.zerver.webhooks")

zerver/lib/request.pyi

@@ -7,14 +7,13 @@
 # types.
 
 from typing import Any, Callable, Text, TypeVar, Optional, Union, Type
-from django.http import HttpResponse
+from zerver.lib.types import ViewFuncT
 
 from zerver.lib.exceptions import JsonableError as JsonableError
 
 Validator = Callable[[str, Any], Optional[str]]
 
 ResultT = TypeVar('ResultT')
-ViewFuncT = TypeVar('ViewFuncT', bound=Callable[..., HttpResponse])
 
 class RequestVariableMissingError(JsonableError): ...
 class RequestVariableConversionError(JsonableError): ...

zerver/lib/types.py

@@ -0,0 +1,4 @@
+from typing import TypeVar, Callable
+from django.http import HttpResponse
+
+ViewFuncT = TypeVar('ViewFuncT', bound=Callable[..., HttpResponse])

zerver/webhooks/beanstalk/view.py

@@ -8,14 +8,13 @@ from django.http import HttpRequest, HttpResponse
 
 from zerver.decorator import authenticated_rest_api_view
 from zerver.lib.actions import check_send_stream_message
+from zerver.lib.types import ViewFuncT
 from zerver.lib.request import REQ, has_request_variables
 from zerver.lib.response import json_success
 from zerver.lib.validator import check_dict
 from zerver.models import UserProfile, get_client
 from zerver.webhooks.github.view import build_message_from_gitlog
 
-ViewFuncT = TypeVar('ViewFuncT', bound=Callable[..., HttpResponse])
-
 # Beanstalk's web hook UI rejects url with a @ in the username section of a url
 # So we ask the user to replace them with %40
 # We manually fix the username here before passing it along to @authenticated_rest_api_view