fix: Replace mutable default parameters with None in feature flag methods

- Changed default parameters from {} to None for all feature flag methods
- Prevents potential bugs from shared mutable defaults across function calls
- Fully backwards compatible - callers see no change in behavior
- Follows Python best practices for function parameter defaults

Also:
- Removed exit() call from example.py that was preventing remaining examples from running
- Expanded get_feature_flag_result example to demonstrate all available fields

Addresses review feedback from PR #284

Author: haacked

example.py

@@ -60,15 +60,18 @@
 print(posthog.get_feature_flag_payload("beta-feature", "distinct_id"))
 print(posthog.get_all_flags_and_payloads("distinct_id"))
 
-# get feature flag result with all details (enabled, variant, payload)
+# get feature flag result with all details (enabled, variant, payload, key, reason)
 result = posthog.get_feature_flag_result("beta-feature", "distinct_id")
 if result:
+    print(f"Flag key: {result.key}")
     print(f"Flag enabled: {result.enabled}")
     print(f"Variant: {result.variant}")
     print(f"Payload: {result.payload}")
+    print(f"Reason: {result.reason}")
+    # get_value() returns the variant if it exists, otherwise the enabled value
+    print(f"Value (variant or enabled): {result.get_value()}")
 
-exit()
-# # Alias a previous distinct id with a new one
+# Alias a previous distinct id with a new one
 
 posthog.alias("distinct_id", "new_distinct_id")
 

posthog/__init__.py

@@ -245,9 +245,9 @@ def capture_exception(
 def feature_enabled(
     key,  # type: str
     distinct_id,  # type: str
-    groups={},  # type: dict
-    person_properties={},  # type: dict
-    group_properties={},  # type: dict
+    groups=None,  # type: Optional[dict]
+    person_properties=None,  # type: Optional[dict]
+    group_properties=None,  # type: Optional[dict]
     only_evaluate_locally=False,  # type: bool
     send_feature_flag_events=True,  # type: bool
     disable_geoip=None,  # type: Optional[bool]
@@ -270,9 +270,9 @@ def feature_enabled(
         "feature_enabled",
         key=key,
         distinct_id=distinct_id,
-        groups=groups,
-        person_properties=person_properties,
-        group_properties=group_properties,
+        groups=groups or {},
+        person_properties=person_properties or {},
+        group_properties=group_properties or {},
         only_evaluate_locally=only_evaluate_locally,
         send_feature_flag_events=send_feature_flag_events,
         disable_geoip=disable_geoip,
@@ -282,9 +282,9 @@ def feature_enabled(
 def get_feature_flag(
     key,  # type: str
     distinct_id,  # type: str
-    groups={},  # type: dict
-    person_properties={},  # type: dict
-    group_properties={},  # type: dict
+    groups=None,  # type: Optional[dict]
+    person_properties=None,  # type: Optional[dict]
+    group_properties=None,  # type: Optional[dict]
     only_evaluate_locally=False,  # type: bool
     send_feature_flag_events=True,  # type: bool
     disable_geoip=None,  # type: Optional[bool]
@@ -315,9 +315,9 @@ def get_feature_flag(
         "get_feature_flag",
         key=key,
         distinct_id=distinct_id,
-        groups=groups,
-        person_properties=person_properties,
-        group_properties=group_properties,
+        groups=groups or {},
+        person_properties=person_properties or {},
+        group_properties=group_properties or {},
         only_evaluate_locally=only_evaluate_locally,
         send_feature_flag_events=send_feature_flag_events,
         disable_geoip=disable_geoip,
@@ -326,9 +326,9 @@ def get_feature_flag(
 
 def get_all_flags(
     distinct_id,  # type: str
-    groups={},  # type: dict
-    person_properties={},  # type: dict
-    group_properties={},  # type: dict
+    groups=None,  # type: Optional[dict]
+    person_properties=None,  # type: Optional[dict]
+    group_properties=None,  # type: Optional[dict]
     only_evaluate_locally=False,  # type: bool
     disable_geoip=None,  # type: Optional[bool]
 ) -> Optional[dict[str, FeatureFlag]]:
@@ -344,9 +344,9 @@ def get_all_flags(
     return _proxy(
         "get_all_flags",
         distinct_id=distinct_id,
-        groups=groups,
-        person_properties=person_properties,
-        group_properties=group_properties,
+        groups=groups or {},
+        person_properties=person_properties or {},
+        group_properties=group_properties or {},
         only_evaluate_locally=only_evaluate_locally,
         disable_geoip=disable_geoip,
     )
@@ -355,23 +355,23 @@ def get_all_flags(
 def get_feature_flag_result(
     key,
     distinct_id,
-    groups={},
-    person_properties={},
-    group_properties={},
+    groups=None,  # type: Optional[dict]
+    person_properties=None,  # type: Optional[dict]
+    group_properties=None,  # type: Optional[dict]
     only_evaluate_locally=False,
     send_feature_flag_events=True,
     disable_geoip=None,  # type: Optional[bool]
 ) -> Optional[FeatureFlagResult]:  # type hint for feature flag result
     """
     Get a FeatureFlagResult object which contains the flag result and payload.
-    
+
     This method evaluates a feature flag and returns a FeatureFlagResult object containing:
     - enabled: Whether the flag is enabled
     - variant: The variant value if the flag has variants
     - payload: The payload associated with the flag (automatically deserialized from JSON)
     - key: The flag key
     - reason: Why the flag was enabled/disabled
-    
+
     Example:
     ```python
     result = posthog.get_feature_flag_result('beta-feature', 'distinct_id')
@@ -385,9 +385,9 @@ def get_feature_flag_result(
         "get_feature_flag_result",
         key=key,
         distinct_id=distinct_id,
-        groups=groups,
-        person_properties=person_properties,
-        group_properties=group_properties,
+        groups=groups or {},
+        person_properties=person_properties or {},
+        group_properties=group_properties or {},
         only_evaluate_locally=only_evaluate_locally,
         send_feature_flag_events=send_feature_flag_events,
         disable_geoip=disable_geoip,
@@ -398,9 +398,9 @@ def get_feature_flag_payload(
     key,
     distinct_id,
     match_value=None,
-    groups={},
-    person_properties={},
-    group_properties={},
+    groups=None,  # type: Optional[dict]
+    person_properties=None,  # type: Optional[dict]
+    group_properties=None,  # type: Optional[dict]
     only_evaluate_locally=False,
     send_feature_flag_events=True,
     disable_geoip=None,  # type: Optional[bool]
@@ -410,9 +410,9 @@ def get_feature_flag_payload(
         key=key,
         distinct_id=distinct_id,
         match_value=match_value,
-        groups=groups,
-        person_properties=person_properties,
-        group_properties=group_properties,
+        groups=groups or {},
+        person_properties=person_properties or {},
+        group_properties=group_properties or {},
         only_evaluate_locally=only_evaluate_locally,
         send_feature_flag_events=send_feature_flag_events,
         disable_geoip=disable_geoip,
@@ -441,18 +441,18 @@ def get_remote_config_payload(
 
 def get_all_flags_and_payloads(
     distinct_id,
-    groups={},
-    person_properties={},
-    group_properties={},
+    groups=None,  # type: Optional[dict]
+    person_properties=None,  # type: Optional[dict]
+    group_properties=None,  # type: Optional[dict]
     only_evaluate_locally=False,
     disable_geoip=None,  # type: Optional[bool]
 ) -> FlagsAndPayloads:
     return _proxy(
         "get_all_flags_and_payloads",
         distinct_id=distinct_id,
-        groups=groups,
-        person_properties=person_properties,
-        group_properties=group_properties,
+        groups=groups or {},
+        person_properties=person_properties or {},
+        group_properties=group_properties or {},
         only_evaluate_locally=only_evaluate_locally,
         disable_geoip=disable_geoip,
     )