Move check_* utils to own file

lib/streamlit/elements/form.py

@@ -194,7 +194,7 @@ def form(
 
         """
         # Import this here to avoid circular imports.
-        from streamlit.elements.utils import (
+        from streamlit.elements.policies import (
             check_cache_replay_rules,
             check_session_state_rules,
         )

lib/streamlit/elements/plotly_chart.py

@@ -452,7 +452,7 @@ def plotly_chart(
             # Run some checks that are only relevant when selections are activated
 
             # Import here to avoid circular imports
-            from streamlit.elements.utils import (
+            from streamlit.elements.policies import (
                 check_cache_replay_rules,
                 check_callback_rules,
                 check_session_state_rules,

lib/streamlit/elements/policies.py

@@ -0,0 +1,102 @@
+# Copyright (c) Streamlit Inc. (2018-2022) Snowflake Inc. (2022-2024)
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# 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
+
+from typing import TYPE_CHECKING, Any
+
+import streamlit
+from streamlit import config, runtime
+from streamlit.elements.form import is_in_form
+from streamlit.errors import StreamlitAPIException, StreamlitAPIWarning
+from streamlit.runtime.scriptrunner.script_run_context import get_script_run_ctx
+from streamlit.runtime.state import WidgetCallback, get_session_state
+
+if TYPE_CHECKING:
+    from streamlit.delta_generator import DeltaGenerator
+
+
+def check_callback_rules(dg: DeltaGenerator, on_change: WidgetCallback | None) -> None:
+    if runtime.exists() and is_in_form(dg) and on_change is not None:
+        raise StreamlitAPIException(
+            "With forms, callbacks can only be defined on the `st.form_submit_button`."
+            " Defining callbacks on other widgets inside a form is not allowed."
+        )
+
+
+_shown_default_value_warning: bool = False
+
+
+def check_session_state_rules(
+    default_value: Any, key: str | None, writes_allowed: bool = True
+) -> None:
+    global _shown_default_value_warning
+
+    if key is None or not runtime.exists():
+        return
+
+    session_state = get_session_state()
+    if not session_state.is_new_state_value(key):
+        return
+
+    if not writes_allowed:
+        raise StreamlitAPIException(
+            f'Values for the widget with key "{key}" cannot be set using `st.session_state`.'
+        )
+
+    if (
+        default_value is not None
+        and not _shown_default_value_warning
+        and not config.get_option("global.disableWidgetStateDuplicationWarning")
+    ):
+        streamlit.warning(
+            f'The widget with key "{key}" was created with a default value but'
+            " also had its value set via the Session State API."
+        )
+        _shown_default_value_warning = True
+
+
+class CachedWidgetWarning(StreamlitAPIWarning):
+    def __init__(self):
+        super().__init__(
+            """
+Your script uses a widget command in a cached function
+(function decorated with `@st.cache_data` or `@st.cache_resource`).
+This code will only be called when we detect a cache "miss",
+which can lead to unexpected results.
+
+How to fix this:
+* Move all widget commands outside the cached function.
+* Or, if you know what you're doing, use `experimental_allow_widgets=True`
+in the cache decorator to enable widget replay and suppress this warning.
+"""
+        )
+
+
+def check_cache_replay_rules() -> None:
+    """Check if a widget is allowed to be used in the current context.
+    More specifically, this checks if the current context is inside a
+    cached function that disallows widget usage. If so, it raises a warning.
+
+    If there are other similar checks in the future, we could extend this
+    function to check for those as well. And rename it to check_widget_usage_rules.
+    """
+    if runtime.exists():
+        from streamlit.runtime.scriptrunner.script_run_context import get_script_run_ctx
+
+        ctx = get_script_run_ctx()
+        if ctx and ctx.disallow_cached_widget_usage:
+            # We use an exception here to show a proper stack trace
+            # that indicates to the user where the issue is.
+            streamlit.exception(CachedWidgetWarning())

lib/streamlit/elements/utils.py

@@ -15,95 +15,13 @@
 from __future__ import annotations
 
 from enum import Enum, EnumMeta
-from typing import TYPE_CHECKING, Any, Iterable, Sequence, overload
+from typing import Any, Iterable, Sequence, overload
 
-import streamlit
-from streamlit import config, runtime, type_util
-from streamlit.elements.form import is_in_form
-from streamlit.errors import StreamlitAPIException, StreamlitAPIWarning
+from streamlit import type_util
 from streamlit.proto.LabelVisibilityMessage_pb2 import LabelVisibilityMessage
-from streamlit.runtime.state import WidgetCallback, get_session_state
 from streamlit.runtime.state.common import RegisterWidgetResult
 from streamlit.type_util import T
 
-if TYPE_CHECKING:
-    from streamlit.delta_generator import DeltaGenerator
-
-
-def check_callback_rules(dg: DeltaGenerator, on_change: WidgetCallback | None) -> None:
-    if runtime.exists() and is_in_form(dg) and on_change is not None:
-        raise StreamlitAPIException(
-            "With forms, callbacks can only be defined on the `st.form_submit_button`."
-            " Defining callbacks on other widgets inside a form is not allowed."
-        )
-
-
-_shown_default_value_warning: bool = False
-
-
-def check_session_state_rules(
-    default_value: Any, key: str | None, writes_allowed: bool = True
-) -> None:
-    global _shown_default_value_warning
-
-    if key is None or not runtime.exists():
-        return
-
-    session_state = get_session_state()
-    if not session_state.is_new_state_value(key):
-        return
-
-    if not writes_allowed:
-        raise StreamlitAPIException(
-            f'Values for the widget with key "{key}" cannot be set using `st.session_state`.'
-        )
-
-    if (
-        default_value is not None
-        and not _shown_default_value_warning
-        and not config.get_option("global.disableWidgetStateDuplicationWarning")
-    ):
-        streamlit.warning(
-            f'The widget with key "{key}" was created with a default value but'
-            " also had its value set via the Session State API."
-        )
-        _shown_default_value_warning = True
-
-
-class CachedWidgetWarning(StreamlitAPIWarning):
-    def __init__(self):
-        super().__init__(
-            """
-Your script uses a widget command in a cached function
-(function decorated with `@st.cache_data` or `@st.cache_resource`).
-This code will only be called when we detect a cache "miss",
-which can lead to unexpected results.
-
-How to fix this:
-* Move all widget commands outside the cached function.
-* Or, if you know what you're doing, use `experimental_allow_widgets=True`
-in the cache decorator to enable widget replay and suppress this warning.
-"""
-        )
-
-
-def check_cache_replay_rules() -> None:
-    """Check if a widget is allowed to be used in the current context.
-    More specifically, this checks if the current context is inside a
-    cached function that disallows widget usage. If so, it raises a warning.
-
-    If there are other similar checks in the future, we could extend this
-    function to check for those as well. And rename it to check_widget_usage_rules.
-    """
-    if runtime.exists():
-        from streamlit.runtime.scriptrunner.script_run_context import get_script_run_ctx
-
-        ctx = get_script_run_ctx()
-        if ctx and ctx.disallow_cached_widget_usage:
-            # We use an exception here to show a proper stack trace
-            # that indicates to the user where the issue is.
-            streamlit.exception(CachedWidgetWarning())
-
 
 def get_label_visibility_proto_value(
     label_visibility_string: type_util.LabelVisibility,
@@ -125,17 +43,15 @@ def maybe_coerce_enum(
     register_widget_result: RegisterWidgetResult[Enum],
     options: type[Enum],
     opt_sequence: Sequence[Any],
-) -> RegisterWidgetResult[Enum]:
-    ...
+) -> RegisterWidgetResult[Enum]: ...
 
 
 @overload
 def maybe_coerce_enum(
     register_widget_result: RegisterWidgetResult[T],
     options: type_util.OptionSequence[T],
     opt_sequence: Sequence[T],
-) -> RegisterWidgetResult[T]:
-    ...
+) -> RegisterWidgetResult[T]: ...
 
 
 def maybe_coerce_enum(register_widget_result, options, opt_sequence):
@@ -168,17 +84,15 @@ def maybe_coerce_enum_sequence(
     register_widget_result: RegisterWidgetResult[list[T]],
     options: type_util.OptionSequence[T],
     opt_sequence: Sequence[T],
-) -> RegisterWidgetResult[list[T]]:
-    ...
+) -> RegisterWidgetResult[list[T]]: ...
 
 
 @overload
 def maybe_coerce_enum_sequence(
     register_widget_result: RegisterWidgetResult[tuple[T, T]],
     options: type_util.OptionSequence[T],
     opt_sequence: Sequence[T],
-) -> RegisterWidgetResult[tuple[T, T]]:
-    ...
+) -> RegisterWidgetResult[tuple[T, T]]: ...
 
 
 def maybe_coerce_enum_sequence(register_widget_result, options, opt_sequence):

lib/streamlit/elements/vega_charts.py

@@ -1652,7 +1652,7 @@ def _vega_lite_chart(
             # Run some checks that are only relevant when selections are activated
 
             # Import here to avoid circular imports
-            from streamlit.elements.utils import (
+            from streamlit.elements.policies import (
                 check_cache_replay_rules,
                 check_callback_rules,
                 check_session_state_rules,

lib/streamlit/elements/widgets/button.py

@@ -575,7 +575,7 @@ def _download_button(
         key = to_key(key)
 
         # Importing these functions here to avoid circular imports
-        from streamlit.elements.utils import (
+        from streamlit.elements.policies import (
             check_cache_replay_rules,
             check_callback_rules,
             check_session_state_rules,
@@ -739,7 +739,7 @@ def _button(
         key = to_key(key)
 
         # Importing these functions here to avoid circular imports
-        from streamlit.elements.utils import (
+        from streamlit.elements.policies import (
             check_cache_replay_rules,
             check_callback_rules,
             check_session_state_rules,

lib/streamlit/elements/widgets/camera_input.py

@@ -21,12 +21,12 @@
 from typing_extensions import TypeAlias
 
 from streamlit.elements.form import current_form_id
-from streamlit.elements.utils import (
+from streamlit.elements.policies import (
     check_cache_replay_rules,
     check_callback_rules,
     check_session_state_rules,
-    get_label_visibility_proto_value,
 )
+from streamlit.elements.utils import get_label_visibility_proto_value
 from streamlit.elements.widgets.file_uploader import _get_upload_files
 from streamlit.proto.CameraInput_pb2 import CameraInput as CameraInputProto
 from streamlit.proto.Common_pb2 import FileUploaderState as FileUploaderStateProto

lib/streamlit/elements/widgets/chat.py

@@ -311,7 +311,7 @@ def chat_input(
         default = ""
         key = to_key(key)
 
-        from streamlit.elements.utils import (
+        from streamlit.elements.policies import (
             check_cache_replay_rules,
             check_callback_rules,
             check_session_state_rules,

lib/streamlit/elements/widgets/checkbox.py

@@ -19,12 +19,12 @@
 from typing import TYPE_CHECKING, cast
 
 from streamlit.elements.form import current_form_id
-from streamlit.elements.utils import (
+from streamlit.elements.policies import (
     check_cache_replay_rules,
     check_callback_rules,
     check_session_state_rules,
-    get_label_visibility_proto_value,
 )
+from streamlit.elements.utils import get_label_visibility_proto_value
 from streamlit.proto.Checkbox_pb2 import Checkbox as CheckboxProto
 from streamlit.runtime.metrics_util import gather_metrics
 from streamlit.runtime.scriptrunner import ScriptRunContext, get_script_run_ctx

lib/streamlit/elements/widgets/color_picker.py

@@ -21,12 +21,12 @@
 
 import streamlit
 from streamlit.elements.form import current_form_id
-from streamlit.elements.utils import (
+from streamlit.elements.policies import (
     check_cache_replay_rules,
     check_callback_rules,
     check_session_state_rules,
-    get_label_visibility_proto_value,
 )
+from streamlit.elements.utils import get_label_visibility_proto_value
 from streamlit.errors import StreamlitAPIException
 from streamlit.proto.ColorPicker_pb2 import ColorPicker as ColorPickerProto
 from streamlit.runtime.metrics_util import gather_metrics

lib/streamlit/elements/widgets/file_uploader.py

@@ -22,12 +22,12 @@
 
 from streamlit import config
 from streamlit.elements.form import current_form_id
-from streamlit.elements.utils import (
+from streamlit.elements.policies import (
     check_cache_replay_rules,
     check_callback_rules,
     check_session_state_rules,
-    get_label_visibility_proto_value,
 )
+from streamlit.elements.utils import get_label_visibility_proto_value
 from streamlit.proto.Common_pb2 import FileUploaderState as FileUploaderStateProto
 from streamlit.proto.Common_pb2 import UploadedFileInfo as UploadedFileInfoProto
 from streamlit.proto.FileUploader_pb2 import FileUploader as FileUploaderProto

lib/streamlit/elements/widgets/multiselect.py

@@ -19,10 +19,12 @@
 from typing import TYPE_CHECKING, Any, Callable, Generic, Sequence, cast, overload
 
 from streamlit.elements.form import current_form_id
-from streamlit.elements.utils import (
+from streamlit.elements.policies import (
     check_cache_replay_rules,
     check_callback_rules,
     check_session_state_rules,
+)
+from streamlit.elements.utils import (
     get_label_visibility_proto_value,
     maybe_coerce_enum_sequence,
 )

lib/streamlit/elements/widgets/number_input.py

@@ -22,12 +22,12 @@
 from typing_extensions import TypeAlias
 
 from streamlit.elements.form import current_form_id
-from streamlit.elements.utils import (
+from streamlit.elements.policies import (
     check_cache_replay_rules,
     check_callback_rules,
     check_session_state_rules,
-    get_label_visibility_proto_value,
 )
+from streamlit.elements.utils import get_label_visibility_proto_value
 from streamlit.errors import StreamlitAPIException
 from streamlit.js_number import JSNumber, JSNumberBoundsException
 from streamlit.proto.NumberInput_pb2 import NumberInput as NumberInputProto

lib/streamlit/elements/widgets/radio.py

@@ -19,13 +19,12 @@
 from typing import TYPE_CHECKING, Any, Callable, Generic, Sequence, cast
 
 from streamlit.elements.form import current_form_id
-from streamlit.elements.utils import (
+from streamlit.elements.policies import (
     check_cache_replay_rules,
     check_callback_rules,
     check_session_state_rules,
-    get_label_visibility_proto_value,
-    maybe_coerce_enum,
 )
+from streamlit.elements.utils import get_label_visibility_proto_value, maybe_coerce_enum
 from streamlit.errors import StreamlitAPIException
 from streamlit.proto.Radio_pb2 import Radio as RadioProto
 from streamlit.runtime.metrics_util import gather_metrics