SF #904720: dict.update should take a 2-tuple sequence like dict.__init_

(Championed by Bob Ippolito.)

The update() method for mappings now accepts all the same argument forms
as the dict() constructor.  This includes item lists and/or keyword
arguments.

2 files changed, 14 insertions, 3 deletions

diff --git a/Doc/lib/libstdtypes.tex b/Doc/lib/libstdtypes.tex
index 7c5cba0dc9..c39be284b1 100644
--- a/Doc/lib/libstdtypes.tex
+++ b/Doc/lib/libstdtypes.tex
@@ -1266,9 +1266,9 @@ arbitrary objects):
           {a copy of \var{a}'s list of (\var{key}, \var{value}) pairs}
           {(3)}
   \lineiii{\var{a}.keys()}{a copy of \var{a}'s list of keys}{(3)}
-  \lineiii{\var{a}.update(\var{b})}
-          {\code{for \var{k} in \var{b}.keys(): \var{a}[\var{k}] = \var{b}[\var{k}]}}
-          {}
+  \lineiii{\var{a}.update(\optional{\var{b}})}
+          {updates (and overwrites) key/value pairs from \var{b}}
+          {(9)}
   \lineiii{\var{a}.fromkeys(\var{seq}\optional{, \var{value}})}
           {Creates a new dictionary with keys from \var{seq} and values set to \var{value}}
           {(7)}			   
@@ -1338,6 +1338,13 @@ new dictionary. \var{value} defaults to \code{None}.  \versionadded{2.3}
 value is given and the key is not found.  \versionadded{2.3}
 \end{description}
 
+\item[(9)] \function{update()} accepts either another mapping object
+or an iterable of key/value pairs (as a tuple or other iterable of
+length two).  If keyword arguments are specified, the mapping is
+then is updated with those key/value pairs:
+\samp{d.update(red=1, blue=2)}.
+\versionchanged[Allowed the argument to be an iterable of key/value
+                pairs and allowed keyword arguments]{2.4}
 
 \subsection{File Objects
             \label{bltin-file-objects}}
diff --git a/Doc/whatsnew/whatsnew24.tex b/Doc/whatsnew/whatsnew24.tex
index eb377bec68..24650fa5bc 100644
--- a/Doc/whatsnew/whatsnew24.tex
+++ b/Doc/whatsnew/whatsnew24.tex
@@ -134,6 +134,10 @@ language.
 
 \begin{itemize}
 
+\item The \method{dict.update()} method now accepts the same
+argument forms as the \class{dict} constructor.  This includes any
+mapping, any iterable of key/value pairs, and/or keyword arguments.       
+
 \item The string methods, \method{ljust()}, \method{rjust()}, and
 \method{center()} now take an optional argument for specifying a
 fill character other than a space.