Improve imports to avoid them inside functions

falcon/asgi_spec.py

@@ -11,9 +11,9 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from __future__ import annotations
 
 """Constants, etc. defined by the ASGI specification."""
+from __future__ import annotations
 
 
 class EventType:

falcon/errors.py

@@ -11,7 +11,6 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from __future__ import annotations
 
 """HTTP error classes and other Falcon-specific errors.
 
@@ -34,19 +33,22 @@ def on_get(self, req, resp):
 
             # -- snip --
 """
+from __future__ import annotations
 
 from datetime import datetime
 from typing import Iterable
 from typing import Optional
+from typing import TYPE_CHECKING
 from typing import Union
 
+from falcon.http_error import HTTPError
 import falcon.status_codes as status
-from falcon.typing import NormalizedHeaders
-from falcon.typing import RawHeaders
 from falcon.util.deprecation import deprecated_args
 from falcon.util.misc import dt_to_http
 
-from .http_error import HTTPError
+if TYPE_CHECKING:
+    from falcon.typing import NormalizedHeaders
+    from falcon.typing import RawHeaders
 
 
 __all__ = (

falcon/hooks.py

@@ -25,15 +25,16 @@
 from typing import Dict
 from typing import List
 from typing import Tuple
+from typing import TYPE_CHECKING
 from typing import Union
 
-from falcon import asgi
 from falcon.constants import COMBINED_METHODS
-from falcon.request import Request
-from falcon.response import Response
 from falcon.util.misc import get_argnames
 from falcon.util.sync import _wrap_non_coroutine_unsafe
 
+if TYPE_CHECKING:
+    import falcon as wsgi
+    from falcon import asgi
 
 _DECORABLE_METHOD_NAME = re.compile(
     r'^on_({})(_\w+)?$'.format('|'.join(method.lower() for method in COMBINED_METHODS))
@@ -246,8 +247,8 @@ async def do_after(
         @wraps(responder)
         def do_after(
             self: Resource,
-            req: Request,
-            resp: Response,
+            req: wsgi.Request,
+            resp: wsgi.Response,
             *args: Any,
             **kwargs: Any,
         ) -> None:
@@ -312,7 +313,11 @@ async def do_before(
 
         @wraps(responder)
         def do_before(
-            self: Resource, req: Request, resp: Response, *args: Any, **kwargs: Any
+            self: Resource,
+            req: wsgi.Request,
+            resp: wsgi.Response,
+            *args: Any,
+            **kwargs: Any,
         ) -> None:
             if args:
                 _merge_responder_args(args, kwargs, extra_argnames)

falcon/http_error.py

@@ -11,24 +11,29 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+"""HTTPError exception class."""
 from __future__ import annotations
 
-"""HTTPError exception class."""
 from collections import OrderedDict
 from typing import MutableMapping
 from typing import Optional
 from typing import Type
+from typing import TYPE_CHECKING
 from typing import Union
 import xml.etree.ElementTree as et
 
 from falcon.constants import MEDIA_JSON
-from falcon.typing import Link
-from falcon.typing import RawHeaders
-from falcon.typing import Serializer
-from falcon.typing import Status
-from falcon.util import code_to_http_status, http_status_to_code, uri
+from falcon.util import code_to_http_status
+from falcon.util import http_status_to_code
+from falcon.util import uri
 from falcon.util.deprecation import deprecated_args
 
+if TYPE_CHECKING:
+    from falcon.typing import Link
+    from falcon.typing import RawHeaders
+    from falcon.typing import Serializer
+    from falcon.typing import Status
+
 
 class HTTPError(Exception):
     """Represents a generic HTTP error.
@@ -205,7 +210,6 @@ def to_json(self, handler: Optional[Serializer] = None) -> bytes:
         obj = self.to_dict(OrderedDict)
         if handler is None:
             handler = _DEFAULT_JSON_HANDLER
-        assert handler
         return handler.serialize(obj, MEDIA_JSON)
 
     def to_xml(self) -> bytes:
@@ -239,4 +243,7 @@ def to_xml(self) -> bytes:
 
 # NOTE: initialized in falcon.media.json, that is always imported since Request/Response
 # are imported by falcon init.
-_DEFAULT_JSON_HANDLER = None
+if TYPE_CHECKING:
+    _DEFAULT_JSON_HANDLER: Serializer
+else:
+    _DEFAULT_JSON_HANDLER = None

falcon/http_status.py

@@ -11,16 +11,19 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+"""HTTPStatus exception class."""
 from __future__ import annotations
 
-"""HTTPStatus exception class."""
 from typing import Optional
+from typing import TYPE_CHECKING
 
-from falcon.typing import RawHeaders
-from falcon.typing import Status
 from falcon.util import http_status_to_code
 from falcon.util.deprecation import AttributeRemovedError
 
+if TYPE_CHECKING:
+    from falcon.typing import RawHeaders
+    from falcon.typing import Status
+
 
 class HTTPStatus(Exception):
     """Represents a generic HTTP status.

falcon/redirects.py

@@ -11,14 +11,17 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+"""HTTPStatus specializations for 3xx redirects."""
 from __future__ import annotations
 
-"""HTTPStatus specializations for 3xx redirects."""
 from typing import Optional
+from typing import TYPE_CHECKING
 
 import falcon
 from falcon.http_status import HTTPStatus
-from falcon.typing import NormalizedHeaders
+
+if TYPE_CHECKING:
+    from falcon.typing import NormalizedHeaders
 
 
 class HTTPMovedPermanently(HTTPStatus):

falcon/request.py

@@ -11,6 +11,8 @@
 # limitations under the License.
 
 """Request class."""
+from __future__ import annotations
+
 from collections import UserDict
 from datetime import datetime
 from io import BytesIO
@@ -26,6 +28,8 @@
 
 # TODO: remove import in falcon 4
 from falcon.forwarded import Forwarded  # NOQA
+from falcon.media import Handlers
+from falcon.media.json import _DEFAULT_JSON_HANDLER
 from falcon.stream import BoundedStream
 from falcon.util import structures
 from falcon.util.misc import isascii
@@ -1887,10 +1891,6 @@ def get_param_as_json(self, name, required=False, store=None, default=None):
             MEDIA_JSON, MEDIA_JSON, raise_not_found=False
         )
         if handler is None:
-            from falcon.media.json import (
-                _DEFAULT_JSON_HANDLER,
-            )  # import here to avoid circular imports
-
             handler = _DEFAULT_JSON_HANDLER
 
         try:
@@ -2104,8 +2104,6 @@ class RequestOptions:
     )
 
     def __init__(self):
-        from falcon.media.handlers import Handlers
-
         self.keep_blank_qs_values = True
         self.auto_parse_form_urlencoded = False
         self.auto_parse_qs_csv = False

falcon/response.py

@@ -13,21 +13,24 @@
 # limitations under the License.
 
 """Response class."""
+from __future__ import annotations
 
 import functools
 import mimetypes
 from typing import Optional
+from typing import TYPE_CHECKING
 
 from falcon.constants import _DEFAULT_STATIC_MEDIA_TYPES
 from falcon.constants import _UNSET
 from falcon.constants import DEFAULT_MEDIA_TYPE
+from falcon.errors import HeaderNotSupported
+from falcon.media import Handlers
 from falcon.response_helpers import format_content_disposition
 from falcon.response_helpers import format_etag_header
 from falcon.response_helpers import format_header_value_list
 from falcon.response_helpers import format_range
 from falcon.response_helpers import header_property
 from falcon.response_helpers import is_ascii_encodable
-from falcon.typing import MediaHandlers
 from falcon.util import dt_to_http
 from falcon.util import http_cookies
 from falcon.util import http_status_to_code
@@ -37,6 +40,8 @@
 from falcon.util.uri import encode_check_escaped as uri_encode
 from falcon.util.uri import encode_value_check_escaped as uri_encode_value
 
+if TYPE_CHECKING:
+    from falcon.typing import MediaHandlers
 
 GMT_TIMEZONE = TimezoneGMT()
 
@@ -198,9 +203,6 @@ def __init__(self, options=None):
         self._media_rendered = _UNSET
 
         self.context = self.context_type()
-        from falcon.errors import HeaderNotSupported
-
-        self._header_not_supported = HeaderNotSupported
 
     @property
     def status_code(self) -> int:
@@ -634,9 +636,7 @@ def get_header(self, name, default=None):
         name = name.lower()
 
         if name == 'set-cookie':
-            raise self._header_not_supported(
-                'Getting Set-Cookie is not currently supported.'
-            )
+            raise HeaderNotSupported('Getting Set-Cookie is not currently supported.')
 
         return self._headers.get(name, default)
 
@@ -672,9 +672,7 @@ def set_header(self, name, value):
         name = name.lower()
 
         if name == 'set-cookie':
-            raise self._header_not_supported(
-                'This method cannot be used to set cookies'
-            )
+            raise HeaderNotSupported('This method cannot be used to set cookies')
 
         self._headers[name] = value
 
@@ -708,9 +706,7 @@ def delete_header(self, name):
         name = name.lower()
 
         if name == 'set-cookie':
-            raise self._header_not_supported(
-                'This method cannot be used to remove cookies'
-            )
+            raise HeaderNotSupported('This method cannot be used to remove ookies')
 
         self._headers.pop(name, None)
 
@@ -804,9 +800,7 @@ def set_headers(self, headers):
 
             name = name.lower()
             if name == 'set-cookie':
-                raise self._header_not_supported(
-                    'This method cannot be used to set cookies'
-                )
+                raise HeaderNotSupported('This method cannot be used to set cookies')
 
             _headers[name] = value
 
@@ -1259,8 +1253,6 @@ class ResponseOptions:
     def __init__(self):
         self.secure_cookies_by_default = True
         self.default_media_type = DEFAULT_MEDIA_TYPE
-        from falcon.media import Handlers
-
         self.media_handlers = Handlers()
 
         if not mimetypes.inited:

falcon/typing.py

@@ -11,9 +11,9 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+"""Shorthand definitions for more complex types."""
 from __future__ import annotations
 
-"""Shorthand definitions for more complex types."""
 import http
 from typing import Any
 from typing import Callable
@@ -23,8 +23,12 @@
 from typing import Optional
 from typing import Pattern
 from typing import Tuple
+from typing import TYPE_CHECKING
 from typing import Union
 
+if TYPE_CHECKING:
+    from falcon.request import Request
+    from falcon.response import Response
 
 Link = Dict[str, str]
 
@@ -43,15 +47,11 @@ def _resolve(
         raise NotImplementedError()
 
 
-from falcon.request import Request  # noqa: E402
-from falcon.response import Response  # noqa: E402
-
-
 # Error handlers
-ErrorHandler = Callable[[Request, Response, BaseException, dict], Any]
+ErrorHandler = Callable[['Request', 'Response', BaseException, dict], Any]
 
 # Error serializers
-ErrorSerializer = Callable[[Request, Response, BaseException], Any]
+ErrorSerializer = Callable[['Request', 'Response', BaseException], Any]
 
 # Sinks
 SinkPrefix = Union[str, Pattern]