FFM-11776 Add decorator context (#104)

Author: erdirowlands

examples/decorator_example/decorator_context.py

@@ -0,0 +1,102 @@
+import functools
+from contextlib import contextmanager
+from featureflags.client import CfClient, FeatureFlagType
+from featureflags.evaluations.auth_target import Target
+
+# Global context to store the ff_client and eval_target
+context = {}
+
+
+@contextmanager
+def feature_flag_context(client: CfClient, target: Target):
+    context['ff_client'] = client
+    context['eval_target'] = target
+    try:
+        yield
+    finally:
+        context.clear()
+
+
+def is_flag_enabled(flag_identifier: str, default_value, expected_value,
+                    fallback_func=None):
+    def decorator_check_flag(func):
+        @functools.wraps(func)
+        def wrapper_check_flag(*args, **kwargs):
+            ff_client = context.get('ff_client')
+            eval_target = context.get('eval_target')
+
+            if ff_client is None or eval_target is None:
+                raise ValueError(
+                    "ff_client and eval_target must be set in context")
+
+            flag_type = ff_client.get_flag_type(flag_identifier)
+
+            variation_methods = {
+                FeatureFlagType.BOOLEAN: lambda: ff_client.bool_variation(
+                    flag_identifier, eval_target, default_value),
+
+                FeatureFlagType.STRING: lambda: ff_client.string_variation(
+                    flag_identifier, eval_target, default_value),
+
+                FeatureFlagType.INT_OR_FLOAT: lambda:
+                ff_client.int_or_float_variation(
+                    flag_identifier, eval_target, default_value),
+
+                FeatureFlagType.JSON: lambda: ff_client.json_variation(
+                    flag_identifier, eval_target, default_value),
+
+                FeatureFlagType.FLAG_NOT_FOUND: lambda: default_value
+            }
+
+            is_enabled = variation_methods[flag_type]()
+            if is_enabled == expected_value:
+                return func(*args, **kwargs)
+            else:
+                if fallback_func:
+                    return fallback_func(*args, **kwargs)
+                return None  # or some default behavior when the flag is not
+                # enabled
+
+        return wrapper_check_flag
+
+    return decorator_check_flag
+
+
+def my_fallback_function(eval_target: Target):
+    print(
+        f"Flag is disabled for target with identifier '"
+        f"{eval_target.identifier}'")
+
+
+# This example is using a string flag. But you can use the annotation
+# with any flag type and the decorator will use the correct variation method.
+# Ensure the expected and default values match the flag
+# type you are evaluating.
+@is_flag_enabled(flag_identifier="stringflag", default_value="default",
+                 expected_value="var12", fallback_func=my_fallback_function)
+def my_string_feature_function(eval_target: Target):
+    print(
+        f"stringflag is enabled for target with identifier '"
+        f"{eval_target.identifier}'")
+
+
+@is_flag_enabled(flag_identifier="boolflag", default_value=False,
+                 expected_value=True, fallback_func=my_fallback_function)
+def my_bool_feature_function(eval_target: Target):
+    print(
+        f"boolflag is enabled for target with identifier '"
+        f"{eval_target.identifier}'")
+
+
+def main():
+    target = Target(identifier='harness')
+    client = CfClient("")
+    client.wait_for_initialization()
+
+    with feature_flag_context(client, target):
+        my_bool_feature_function(target)
+        my_string_feature_function(target)
+
+
+if __name__ == "__main__":
+    main()