[Python-checkins] r51686 - python/trunk/Doc/lib/libdecimal.tex

Sat Sep 2 06:04:18 CEST 2006

Author: nick.coghlan
Date: Sat Sep 2 06:04:18 2006
New Revision: 51686
Modified:
 python/trunk/Doc/lib/libdecimal.tex
Log:
Further corrections to the decimal module context management documentation
Modified: python/trunk/Doc/lib/libdecimal.tex
==============================================================================

--- python/trunk/Doc/lib/libdecimal.tex	(original)
+++ python/trunk/Doc/lib/libdecimal.tex	Sat Sep 2 06:04:18 2006
@@ -443,36 +443,33 @@
 \end{funcdesc} 
 
 Beginning with Python 2.5, you can also use the \keyword{with} statement
-to temporarily change the active context.
+and the \function{localcontext()} function to temporarily change the
+active context.
 
 \begin{funcdesc}{localcontext}{\optional{c}}
 Return a context manager that will set the current context for
 the active thread to a copy of \var{c} on entry to the with statement
- and restore the previous context when exiting the with statement.
+ and restore the previous context when exiting the with statement. If
+ no context is specified, a copy of the current context is used.
 
 For example the following code increases the current decimal precision
- by 2 places, performs a calculation, and then automatically restores
+ by 42 places, performs a calculation, and then automatically restores
 the previous context:
 \begin{verbatim}
 from __future__ import with_statement
 import decimal
 
 with decimal.localcontext() as ctx:
- ctx.prec += 2 # add 2 more digits of precision
+ ctx.prec = 42 # Perform a high precision calculation
 s = calculate_something()
 s = +s # Round the final result back to the default precision
 \end{verbatim}
-\end{funcdesc}
 
-The context that's active in the body of the \keyword{with} statement is
-a \emph{copy} of the context you provided to the \keyword{with}
-statement, so modifying its attributes doesn't affect anything except
-that temporary copy.
-
-You can use any decimal context in a \keyword{with} statement, but if
-you just want to make a temporary change to some aspect of the current
-context, it's easiest to just use \function{getcontext()} as shown
-above.
+ The context that is held by the context manager and made active in the
+ body of the \keyword{with} statement is a \emph{copy} of the context
+ you provide to this function, so modifying its attributes doesn't
+ affect anything except that temporary copy.
+\end{funcdesc}
 
 New contexts can also be created using the \class{Context} constructor
 described below. In addition, the module provides three pre-made
