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authorFred Drake <fdrake@acm.org>2000-09-19 18:10:05 (GMT)
committerFred Drake <fdrake@acm.org>2000-09-19 18:10:05 (GMT)
commit1156f623483b1c49c1262b8e28a7ac1279e5ba4e (patch)
treeb37954a53edd8b29736e1f0348392b889587f5ab /Doc
parentb96e0e5e65e957235f2b4e4aeaf3041f590af014 (diff)
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Many small clarifications, including many suggested by email.
Diffstat (limited to 'Doc')
-rw-r--r--Doc/ref/ref5.tex35
1 files changed, 18 insertions, 17 deletions
diff --git a/Doc/ref/ref5.tex b/Doc/ref/ref5.tex
index 1d2f6fe..46fdd6d 100644
--- a/Doc/ref/ref5.tex
+++ b/Doc/ref/ref5.tex
@@ -676,11 +676,10 @@ converted to a common type.
\section{Comparisons\label{comparisons}}
\index{comparison}
-Contrary to \C, all comparison operations in Python have the same
-priority, which is lower than that of any arithmetic, shifting or
-bitwise operation. Also contrary to \C, expressions like
-\code{a < b < c} have the interpretation that is conventional in
-mathematics:
+Unlike C, all comparison operations in Python have the same priority,
+which is lower than that of any arithmetic, shifting or bitwise
+operation. Also unlike C, expressions like \code{a < b < c} have the
+interpretation that is conventional in mathematics:
\indexii{C}{language}
\begin{verbatim}
@@ -708,11 +707,12 @@ perfectly legal (though perhaps not pretty).
The forms \code{<>} and \code{!=} are equivalent; for consistency with
C, \code{!=} is preferred; where \code{!=} is mentioned below
-\code{<>} is also acceptable. At some point in the (far) future,
-\code{<>} may become obsolete.
+\code{<>} is also accepted. The \code{<>} spelling is considered
+obsolescent.
-The operators \texttt{"<", ">", "==", ">=", "<="}, and \texttt{"!="} compare
-the values of two objects. The objects needn't have the same type.
+The operators \code{<}, \code{>}, \code{==}, \code{>=}, \code{<=}, and
+\code{!=} compare
+the values of two objects. The objects need not have the same type.
If both are numbers, they are coverted to a common type. Otherwise,
objects of different types \emph{always} compare unequal, and are
ordered consistently but arbitrarily.
@@ -732,7 +732,8 @@ Numbers are compared arithmetically.
\item
Strings are compared lexicographically using the numeric equivalents
(the result of the built-in function \function{ord()}) of their
-characters.
+characters. Unicode and 8-bit strings are fully interoperable in this
+behavior.
\item
Tuples and lists are compared lexicographically using comparison of
@@ -765,19 +766,19 @@ For the list, tuple types, \code{\var{x} in \var{y}} is true if and only
if there exists such an index \var{i} such that
\code{var{x} == \var{y}[\var{i}]} is true.
-For the Unicode and string types, \code{\var{x} in \var{y}} is true if and only
-if there exists such an index \var{i} such that
-\code{var{x} == \var{y}[\var{i}]} is true. If \code{\var{x}} is not
-a string of length \code{1} or a unicode object of length \code{1},
-a \exception{TypeError} exception is raised.
+For the Unicode and string types, \code{\var{x} in \var{y}} is true if
+and only if there exists an index \var{i} such that \code{\var{x} ==
+\var{y}[\var{i}]} is true. If \code{\var{x}} is not a string or
+Unicode object of length \code{1}, a \exception{TypeError} exception
+is raised.
For user-defined classes which define the \method{__contains__()} method,
\code{\var{x} in \var{y}} is true if and only if
\code{\var{y}.__contains__(\var{x})} is true.
For user-defined classes which do not define \method{__contains__()} and
-do define \var{__getitem__}, \code{\var{x} in \var{y}} is true if and only
-if there is a non-negative integer index \var{i} such that
+do define \method{__getitem__()}, \code{\var{x} in \var{y}} is true if
+and only if there is a non-negative integer index \var{i} such that
\code{\var{x} == \var{y}[\var{i}]}, and all lower integer indices
do not raise \exception{IndexError} exception. (If any other exception
is raised, it is as if \keyword{in} raised that exception).