From: Guido van Rossum <guido@python.org>
Date: Tue, 16 Jul 2002 19:53:39 +0000 (+0000)
Subject: Record the decision that StopIteration is a sink state (see recent
X-Git-Tag: v2.3c1~4992
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=9534e14033f26b32ed75c02a6a51bfe47c7f16a9;p=python

Record the decision that StopIteration is a sink state (see recent
discussion in python-dev with subject "Termination of two-arg iter()").

Implementation will follow.
---

diff --git a/Doc/lib/libstdtypes.tex b/Doc/lib/libstdtypes.tex
index 1a07d3c984..aabc9bfa48 100644
--- a/Doc/lib/libstdtypes.tex
+++ b/Doc/lib/libstdtypes.tex
@@ -377,6 +377,13 @@ general and specific sequence types, dictionaries, and other more
 specialized forms.  The specific types are not important beyond their
 implementation of the iterator protocol.
 
+The intention of the protocol is that once an iterator's
+\method{next()} method raises \exception{StopIteration}, it will
+continue to do so on subsequent calls.  Implementations that
+do not obey this property are deemed broken.  (This constraint
+was added in Python 2.3; in Python 2.2, various iterators are
+broken according to this rule.)
+
 
 \subsection{Sequence Types \label{typesseq}}