From 4e4a925f0b63de1a45905447be043ef30b86adcb Mon Sep 17 00:00:00 2001
From: Dominic Kempf <dominic.kempf@iwr.uni-heidelberg.de>
Date: Thu, 28 Feb 2019 04:41:28 +0100
Subject: [PATCH] Cache hash value of ImmutableRecord
Due to the data structure to being intended immutable, the hash value
cannot change during object lifetime. This commit caches the value
upon first evaluation.
---
pytools/__init__.py | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/pytools/__init__.py b/pytools/__init__.py
index 57e3378..c096e99 100644
--- a/pytools/__init__.py
+++ b/pytools/__init__.py
@@ -315,12 +315,18 @@ class Record(RecordWithoutPickling):
class ImmutableRecordWithoutPickling(RecordWithoutPickling):
"Hashable record. Does not explicitly enforce immutability."
+ def __init__(self, *args, **kwargs):
+ RecordWithoutPickling.__init__(self, *args, **kwargs)
+ self._cached_hash = None
def __hash__(self):
- return hash(
+ if self._cached_hash is None:
+ self._cached_hash = hash(
(type(self),) + tuple(getattr(self, field)
for field in self.__class__.fields))
+ return self._cached_hash
+
class ImmutableRecord(ImmutableRecordWithoutPickling, Record):
pass
--
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