Restructured library documentation
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+\section{Built-in Exceptions}
+
+Exceptions are string objects. Two distinct string objects with the
+same value are different exceptions. This is done to force programmers
+to use exception names rather than their string value when specifying
+exception handlers. The string value of all built-in exceptions is
+their name, but this is not a requirement for user-defined exceptions
+or exceptions defined by library modules.
+
+The following exceptions can be generated by the interpreter or
+built-in functions. Except where mentioned, they have an `associated
+value' indicating the detailed cause of the error. This may be a
+string or a tuple containing several items of information (e.g., an
+error code and a string explaining the code).
+
+User code can raise built-in exceptions. This can be used to test an
+exception handler or to report an error condition `just like' the
+situation in which the interpreter raises the same exception; but
+beware that there is nothing to prevent user code from raising an
+inappropriate error.
+
+\renewcommand{\indexsubitem}{(built-in exception)}
+
+\begin{excdesc}{AttributeError}
+% xref to attribute reference?
+ Raised when an attribute reference or assignment fails. (When an
+ object does not support attributes references or attribute assignments
+ at all, \code{TypeError} is raised.)
+\end{excdesc}
+
+\begin{excdesc}{EOFError}
+% XXXJH xrefs here
+ Raised when one of the built-in functions (\code{input()} or
+ \code{raw_input()}) hits an end-of-file condition (\EOF{}) without
+ reading any data.
+% XXXJH xrefs here
+ (N.B.: the \code{read()} and \code{readline()} methods of file
+ objects return an empty string when they hit \EOF{}.) No associated value.
+\end{excdesc}
+
+\begin{excdesc}{IOError}
+% XXXJH xrefs here
+ Raised when an I/O operation (such as a \code{print} statement, the
+ built-in \code{open()} function or a method of a file object) fails
+ for an I/O-related reason, e.g., `file not found', `disk full'.
+\end{excdesc}
+
+\begin{excdesc}{ImportError}
+% XXXJH xref to import statement?
+ Raised when an \code{import} statement fails to find the module
+ definition or when a \code{from {\rm \ldots} import} fails to find a
+ name that is to be imported.
+\end{excdesc}
+
+\begin{excdesc}{IndexError}
+% XXXJH xref to sequences
+ Raised when a sequence subscript is out of range. (Slice indices are
+ silently truncated to fall in the allowed range; if an index is not a
+ plain integer, \code{TypeError} is raised.)
+\end{excdesc}
+
+\begin{excdesc}{KeyError}
+% XXXJH xref to mapping objects?
+ Raised when a mapping (dictionary) key is not found in the set of
+ existing keys.
+\end{excdesc}
+
+\begin{excdesc}{KeyboardInterrupt}
+ Raised when the user hits the interrupt key (normally
+ \kbd{Control-C} or
+\key{DEL}). During execution, a check for interrupts is made regularly.
+% XXXJH xrefs here
+ Interrupts typed when a built-in function \code{input()} or
+ \code{raw_input()}) is waiting for input also raise this exception. No
+ associated value.
+\end{excdesc}
+
+\begin{excdesc}{MemoryError}
+ Raised when an operation runs out of memory but the situation may
+ still be rescued (by deleting some objects). The associated value is
+ a string indicating what kind of (internal) operation ran out of memory.
+ Note that because of the underlying memory management architecture
+ (\C{}'s \code{malloc()} function), the interpreter may not always be able
+ to completely recover from this situation; it nevertheless raises an
+ exception so that a stack traceback can be printed, in case a run-away
+ program was the cause.
+\end{excdesc}
+
+\begin{excdesc}{NameError}
+ Raised when a local or global name is not found. This applies only
+ to unqualified names. The associated value is the name that could
+ not be found.
+\end{excdesc}
+
+\begin{excdesc}{OverflowError}
+% XXXJH reference to long's and/or int's?
+ Raised when the result of an arithmetic operation is too large to be
+ represented. This cannot occur for long integers (which would rather
+ raise \code{MemoryError} than give up). Because of the lack of
+ standardization of floating point exception handling in \C{}, most
+ floating point operations also aren't checked. For plain integers,
+ all operations that can overflow are checked except left shift, where
+ typical applications prefer to drop bits than raise an exception.
+\end{excdesc}
+
+\begin{excdesc}{RuntimeError}
+ Raised when an error is detected that doesn't fall in any of the
+ other categories. The associated value is a string indicating what
+ precisely went wrong. (This exception is a relic from a previous
+ version of the interpreter; it is not used any more except by some
+ extension modules that haven't been converted to define their own
+ exceptions yet.)
+\end{excdesc}
+
+\begin{excdesc}{SyntaxError}
+% XXXJH xref to these functions?
+ Raised when the parser encounters a syntax error. This may occur in
+ an \code{import} statement, in an \code{exec} statement, in a call
+ to the built-in function \code{eval()} or \code{input()}, or
+ when reading the initial script or standard input (also
+ interactively).
+\end{excdesc}
+
+\begin{excdesc}{SystemError}
+ Raised when the interpreter finds an internal error, but the
+ situation does not look so serious to cause it to abandon all hope.
+ The associated value is a string indicating what went wrong (in
+ low-level terms).
+
+ You should report this to the author or maintainer of your Python
+ interpreter. Be sure to report the version string of the Python
+ interpreter (\code{sys.version}; it is also printed at the start of an
+ interactive Python session), the exact error message (the exception's
+ associated value) and if possible the source of the program that
+ triggered the error.
+\end{excdesc}
+
+\begin{excdesc}{SystemExit}
+% XXXJH xref to module sys?
+ This exception is raised by the \code{sys.exit()} function. When it
+ is not handled, the Python interpreter exits; no stack traceback is
+ printed. If the associated value is a plain integer, it specifies the
+ system exit status (passed to \C{}'s \code{exit()} function); if it is
+ \code{None}, the exit status is zero; if it has another type (such as
+ a string), the object's value is printed and the exit status is one.
+
+ A call to \code{sys.exit} is translated into an exception so that
+ clean-up handlers (\code{finally} clauses of \code{try} statements)
+ can be executed, and so that a debugger can execute a script without
+ running the risk of losing control. The \code{posix._exit()} function
+ can be used if it is absolutely positively necessary to exit
+ immediately (e.g., after a \code{fork()} in the child process).
+\end{excdesc}
+
+\begin{excdesc}{TypeError}
+ Raised when a built-in operation or function is applied to an object
+ of inappropriate type. The associated value is a string giving
+ details about the type mismatch.
+\end{excdesc}
+
+\begin{excdesc}{ValueError}
+ Raised when a built-in operation or function receives an argument
+ that has the right type but an inappropriate value, and the
+ situation is not described by a more precise exception such as
+ \code{IndexError}.
+\end{excdesc}
+
+\begin{excdesc}{ZeroDivisionError}
+ Raised when the second argument of a division or modulo operation is
+ zero. The associated value is a string indicating the type of the
+ operands and the operation.
+\end{excdesc}