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| -rw-r--r-- | Doc/library/exceptions.rst | 26 |
1 files changed, 13 insertions, 13 deletions
diff --git a/Doc/library/exceptions.rst b/Doc/library/exceptions.rst index 5892154..271a5c8 100644 --- a/Doc/library/exceptions.rst +++ b/Doc/library/exceptions.rst @@ -353,18 +353,17 @@ The following exceptions are the exceptions that are usually raised. .. exception:: SystemExit - This exception is raised by the :func:`sys.exit` function. When it is not - handled, the Python interpreter exits; no stack traceback is printed. If the - associated value is an integer, it specifies the system exit status (passed - to C's :c:func:`exit` function); if it is ``None``, the exit status is zero; - if it has another type (such as a string), the object's value is printed and + This exception is raised by the :func:`sys.exit` function. It inherits from + :exc:`BaseException` instead of :exc:`Exception` so that it is not accidentally + caught by code that catches :exc:`Exception`. This allows the exception to + properly propagate up and cause the interpreter to exit. When it is not + handled, the Python interpreter exits; no stack traceback is printed. The + constructor accepts the same optional argument passed to :func:`sys.exit`. + If the value is an integer, it specifies the system exit status (passed to + C's :c:func:`exit` function); if it is ``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. - Instances have an attribute :attr:`!code` which is set to the proposed exit - status or error message (defaulting to ``None``). Also, this exception derives - directly from :exc:`BaseException` and not :exc:`Exception`, since it is not - technically an error. - A call to :func:`sys.exit` is translated into an exception so that clean-up handlers (:keyword:`finally` clauses of :keyword:`try` statements) can be executed, and so that a debugger can execute a script without running the risk @@ -372,9 +371,10 @@ The following exceptions are the exceptions that are usually raised. absolutely positively necessary to exit immediately (for example, in the child process after a call to :func:`os.fork`). - The exception inherits from :exc:`BaseException` instead of :exc:`Exception` so - that it is not accidentally caught by code that catches :exc:`Exception`. This - allows the exception to properly propagate up and cause the interpreter to exit. + .. attribute:: code + + The exit status or error message that is passed to the constructor. + (Defaults to ``None``.) .. exception:: TypeError |