From 0c4755935251c2231086fe6636ab2104b7a8edc6 Mon Sep 17 00:00:00 2001
From: Fred Drake <fdrake@acm.org>
Date: Thu, 7 Dec 2000 04:49:34 +0000
Subject: Added a note that objects which emulate built-in types should only
 implement as many of the relevant methods as make sense for the particular
 information being modelled.

---
 Doc/ref/ref3.tex | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Doc/ref/ref3.tex b/Doc/ref/ref3.tex
index 905a001..0222110 100644
--- a/Doc/ref/ref3.tex
+++ b/Doc/ref/ref3.tex
@@ -841,6 +841,13 @@ a list object, \code{x.__getitem__(i)} is not equivalent to
 operation raise an exception when no appropriate method is defined.
 \withsubitem{(mapping object method)}{\ttindex{__getitem__()}}
 
+When implementing a class that emulates any built-in type, it is
+important that the emulation only be implemented to the degree that it
+makes sense for the object being modelled.  For example, some
+sequences may work well with retrieval of individual elements, but
+extracting a slice may not make sense.  (One example of this is the
+\class{NodeList} interface in the W3C's Document Object Model.)
+
 
 \subsection{Basic customization\label{customization}}
 
-- 
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