@@ -10,7 +10,8 @@ \section{Built-in Exceptions}
1010converted to class objects, and users are encouraged to do the same.
1111The exceptions are defined in the module \module {exceptions}. This
1212module never needs to be imported explicitly: the exceptions are
13- provided in the built-in namespace.
13+ provided in the built-in namespace as well as the \module {exceptions}
14+ module.
1415
1516Two distinct string objects with the same value are considered different
1617exceptions. This is done to force programmers to use exception names
@@ -47,6 +48,13 @@ \section{Built-in Exceptions}
4748beware that there is nothing to prevent user code from raising an
4849inappropriate error.
4950
51+ The built-in exception classes can be sub-classed to define new
52+ exceptions; programmers are encouraged to at least derive new
53+ exceptions from the \exception {Exception} base class. More
54+ information on defining exceptions is available in the
55+ \citetitle [../tut/tut.html]{Python Tutorial } under the heading
56+ `` User-defined Exceptions.''
57+
5058\setindexsubitem {(built-in exception base class)}
5159
5260The following exceptions are only used as base classes for other
@@ -254,12 +262,10 @@ \section{Built-in Exceptions}
254262 when reading the initial script or standard input (also
255263 interactively).
256264
257- When class exceptions are used, instances of this class have
258- atttributes \member {filename}, \member {lineno}, \member {offset} and
259- \member {text} for easier access to the details; for string exceptions,
260- the associated value is usually a tuple of the form
261- \code {(message, (filename, lineno, offset, text))}.
262- For class exceptions, \function {str()} returns only the message.
265+ Instances of this class have atttributes \member {filename},
266+ \member {lineno}, \member {offset} and \member {text} for easier access
267+ to the details. \function {str()} of the exception instance returns
268+ only the message.
263269\end {excdesc }
264270
265271\begin {excdesc }{SystemError}
@@ -269,7 +275,7 @@ \section{Built-in Exceptions}
269275 low-level terms).
270276
271277 You should report this to the author or maintainer of your Python
272- interpreter. Be sure to report the version string of the Python
278+ interpreter. Be sure to report the version of the Python
273279 interpreter (\code {sys.version}; it is also printed at the start of an
274280 interactive Python session), the exact error message (the exception's
275281 associated value) and if possible the source of the program that
@@ -342,7 +348,7 @@ \section{Built-in Exceptions}
342348\end {excdesc }
343349
344350
345- \setindexsubitem {(built-in warning category )}
351+ \setindexsubitem {(built-in warning)}
346352
347353The following exceptions are used as warning categories; see the
348354\module {warnings} module for more information.
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