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author | Thomas Wouters <thomas@python.org> | 2006-04-21 10:40:58 (GMT) |
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committer | Thomas Wouters <thomas@python.org> | 2006-04-21 10:40:58 (GMT) |
commit | 49fd7fa4431da299196d74087df4a04f99f9c46f (patch) | |
tree | 35ace5fe78d3d52c7a9ab356ab9f6dbf8d4b71f4 /Doc/lib/libdecimal.tex | |
parent | 9ada3d6e29d5165dadacbe6be07bcd35cfbef59d (diff) | |
download | cpython-49fd7fa4431da299196d74087df4a04f99f9c46f.zip cpython-49fd7fa4431da299196d74087df4a04f99f9c46f.tar.gz cpython-49fd7fa4431da299196d74087df4a04f99f9c46f.tar.bz2 |
Merge p3yk branch with the trunk up to revision 45595. This breaks a fair
number of tests, all because of the codecs/_multibytecodecs issue described
here (it's not a Py3K issue, just something Py3K discovers):
http://mail.python.org/pipermail/python-dev/2006-April/064051.html
Hye-Shik Chang promised to look for a fix, so no need to fix it here. The
tests that are expected to break are:
test_codecencodings_cn
test_codecencodings_hk
test_codecencodings_jp
test_codecencodings_kr
test_codecencodings_tw
test_codecs
test_multibytecodec
This merge fixes an actual test failure (test_weakref) in this branch,
though, so I believe merging is the right thing to do anyway.
Diffstat (limited to 'Doc/lib/libdecimal.tex')
-rw-r--r-- | Doc/lib/libdecimal.tex | 28 |
1 files changed, 26 insertions, 2 deletions
diff --git a/Doc/lib/libdecimal.tex b/Doc/lib/libdecimal.tex index 092f038..ffc3363 100644 --- a/Doc/lib/libdecimal.tex +++ b/Doc/lib/libdecimal.tex @@ -442,9 +442,33 @@ the \function{getcontext()} and \function{setcontext()} functions: Set the current context for the active thread to \var{c}. \end{funcdesc} -New contexts can formed using the \class{Context} constructor described below. -In addition, the module provides three pre-made contexts: +Beginning with Python 2.5, you can also use the \keyword{with} statement +to temporarily change the active context. For example the following code +increases the current decimal precision by 2 places, performs a +calculation, and then automatically restores the previous context: +\begin{verbatim} +from __future__ import with_statement +import decimal + +with decimal.getcontext() as ctx: + ctx.prec += 2 # add 2 more digits of precision + calculate_something() +\end{verbatim} + +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. + +New contexts can also be created using the \class{Context} constructor +described below. In addition, the module provides three pre-made +contexts: \begin{classdesc*}{BasicContext} This is a standard context defined by the General Decimal Arithmetic |