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authorBerker Peksag <berker.peksag@gmail.com>2016-11-06 18:15:48 (GMT)
committerBerker Peksag <berker.peksag@gmail.com>2016-11-06 18:15:48 (GMT)
commit87170d672afea720f7f05c2a7c55d4cbed2e1fe4 (patch)
tree1c9480027b55e7903b636ca543b23b79391c79a9 /Doc/tutorial
parent60e49aa7560ca70bc5de461abc68eb72d8739e17 (diff)
parentcea632ece5f127f10f6b831fc8dfc72acab181d7 (diff)
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Issue #21864: Merge from 3.5
Diffstat (limited to 'Doc/tutorial')
-rw-r--r--Doc/tutorial/classes.rst49
-rw-r--r--Doc/tutorial/errors.rst32
2 files changed, 31 insertions, 50 deletions
diff --git a/Doc/tutorial/classes.rst b/Doc/tutorial/classes.rst
index 03b77e0..75c79d2 100644
--- a/Doc/tutorial/classes.rst
+++ b/Doc/tutorial/classes.rst
@@ -744,55 +744,6 @@ object with the method :meth:`m`, and ``m.__func__`` is the function object
corresponding to the method.
-.. _tut-exceptionclasses:
-
-Exceptions Are Classes Too
-==========================
-
-User-defined exceptions are identified by classes as well. Using this mechanism
-it is possible to create extensible hierarchies of exceptions.
-
-There are two new valid (semantic) forms for the :keyword:`raise` statement::
-
- raise Class
-
- raise Instance
-
-In the first form, ``Class`` must be an instance of :class:`type` or of a
-class derived from it. The first form is a shorthand for::
-
- raise Class()
-
-A class in an :keyword:`except` clause is compatible with an exception if it is
-the same class or a base class thereof (but not the other way around --- an
-except clause listing a derived class is not compatible with a base class). For
-example, the following code will print B, C, D in that order::
-
- class B(Exception):
- pass
- class C(B):
- pass
- class D(C):
- pass
-
- for cls in [B, C, D]:
- try:
- raise cls()
- except D:
- print("D")
- except C:
- print("C")
- except B:
- print("B")
-
-Note that if the except clauses were reversed (with ``except B`` first), it
-would have printed B, B, B --- the first matching except clause is triggered.
-
-When an error message is printed for an unhandled exception, the exception's
-class name is printed, then a colon and a space, and finally the instance
-converted to a string using the built-in function :func:`str`.
-
-
.. _tut-iterators:
Iterators
diff --git a/Doc/tutorial/errors.rst b/Doc/tutorial/errors.rst
index 291fb4d..759588f 100644
--- a/Doc/tutorial/errors.rst
+++ b/Doc/tutorial/errors.rst
@@ -120,6 +120,33 @@ name multiple exceptions as a parenthesized tuple, for example::
... except (RuntimeError, TypeError, NameError):
... pass
+A class in an :keyword:`except` clause is compatible with an exception if it is
+the same class or a base class thereof (but not the other way around --- an
+except clause listing a derived class is not compatible with a base class). For
+example, the following code will print B, C, D in that order::
+
+ class B(Exception):
+ pass
+
+ class C(B):
+ pass
+
+ class D(C):
+ pass
+
+ for cls in [B, C, D]:
+ try:
+ raise cls()
+ except D:
+ print("D")
+ except C:
+ print("C")
+ except B:
+ print("B")
+
+Note that if the except clauses were reversed (with ``except B`` first), it
+would have printed B, B, B --- the first matching except clause is triggered.
+
The last except clause may omit the exception name(s), to serve as a wildcard.
Use this with extreme caution, since it is easy to mask a real programming error
in this way! It can also be used to print an error message and then re-raise
@@ -219,7 +246,10 @@ exception to occur. For example::
The sole argument to :keyword:`raise` indicates the exception to be raised.
This must be either an exception instance or an exception class (a class that
-derives from :class:`Exception`).
+derives from :class:`Exception`). If an exception class is passed, it will
+be implicitly instantiated by calling its constructor with no arguments::
+
+ raise ValueError # shorthand for 'raise ValueError()'
If you need to determine whether an exception was raised but don't intend to
handle it, a simpler form of the :keyword:`raise` statement allows you to