From ca554f62c446c6cfa07b9bb56466992f5d7624be Mon Sep 17 00:00:00 2001
From: Jean-Paul Calderone <exarkun@twistedmatrix.com>
Date: Thu, 23 Sep 2021 09:41:41 -0400
Subject: [PATCH] Make a safer way to check if an interface has an attribute
---
src/_zkapauthorizer/foolscap.py | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/src/_zkapauthorizer/foolscap.py b/src/_zkapauthorizer/foolscap.py
index 701a5ea..1478d76 100644
--- a/src/_zkapauthorizer/foolscap.py
+++ b/src/_zkapauthorizer/foolscap.py
@@ -141,6 +141,20 @@ def add_arguments(schema, kwargs):
return modified_schema
+def remoteinterface_hasattr(ri, name):
+ """
+ :param InterfaceClass ri: A ``RemoteInterface`` to inspect.
+ :param str name: The name of an attribute.
+
+ :return bool: ``True`` if and only if ``ri`` has the attribute named by
+ ``name``, ``False`` otherwise.
+ """
+ try:
+ ri[name]
+ except KeyError:
+ return False
+ return True
+
class RIPrivacyPassAuthorizedStorageServer(RemoteInterface):
"""
@@ -162,7 +176,7 @@ class RIPrivacyPassAuthorizedStorageServer(RemoteInterface):
add_lease = add_passes(RIStorageServer["add_lease"])
- if "renew_lease" in RIStorageServer:
+ if remoteinterface_hasattr(RIStorageServer, "renew_lease"):
# Tahoe-LAFS 1.16.0 drops renew_lease from the interface. Do likewise
# here, if we discover we have a version of Tahoe that has done so.
# If Tahoe has dropped this method then nothing in Tahoe is going to
--
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