From f558da0f905d8598b05bed0a5046ca72efe1f5af Mon Sep 17 00:00:00 2001 From: Tim Peters Date: Tue, 28 Jan 2003 02:09:55 +0000 Subject: [PATCH] save_tuple(): Minor rewriting, and added a comment about the subtlety created by recursive tuples. --- Lib/pickle.py | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) diff --git a/Lib/pickle.py b/Lib/pickle.py index 62f7a5849a..25a5a55626 100644 --- a/Lib/pickle.py +++ b/Lib/pickle.py @@ -454,21 +454,26 @@ class Pickler: save = self.save memo = self.memo - d = id(object) - write(MARK) - for element in object: save(element) - if len(object) and d in memo: + if object and id(object) in memo: + # Subtle. d was not in memo when we entered save_tuple(), so + # the process of saving the tuple's elements must have saved + # the tuple itself: the tuple is recursive. The proper action + # now is to throw away everything we put on the stack, and + # simply GET the tuple (it's already constructed). This check + # could have been done in the "for element" loop instead, but + # recursive tuples are a rare thing. + get = self.get(memo[id(object)][0]) if self.bin: - write(POP_MARK + self.get(memo[d][0])) - return - - write(POP * (len(object) + 1) + self.get(memo[d][0])) + write(POP_MARK + get) + else: # proto 0 -- POP_MARK not available + write(POP * (len(object) + 1) + get) return + # No recursion (including the empty-tuple case). self.write(TUPLE) self.memoize(object) -- 2.50.1