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Python Error Classes


exception DeprecationWarning¶ Base class for warnings about deprecated features. The os._exit() function can be used if it is absolutely positively necessary to exit immediately (for example, in the child process after a call to os.fork()). StandardErrorBase class for all built-in exceptions except StopIteration and SystemExit. exception SyntaxWarning¶ Base class for warnings about dubious syntax. http://vealcine.com/python-exception/python-default-error-classes.php

exception UnicodeTranslateError¶ Raised when a Unicode-related error occurs during translating. This can be raised directly by codecs.lookup(). 5.2. Exception hierarchy Previous topic 4. for line in open("myfile.txt"): print line, The problem with this code is that it leaves the file open for an indeterminate amount of time after the code has finished executing. https://docs.python.org/2/library/exceptions.html

Python Custom Exception

So make sure that you call it properly: Let's assume that you saved this program as "exception_test.py". ImportWarning Warn about problems importing a module. New in version 2.5.

When an exception occurs, it may have an associated value, also known as the exception's argument. The errno attribute is then an approximate translation, in POSIX terms, of that native error code. with open("myfile.txt") as f: for line in f: print(line, end="") After the statement is executed, the file f is always closed, even if a problem was encountered while processing the lines. Python Filenotfounderror Page Contents exceptions - Built-in error classes Description Base Classes BaseException Exception StandardError ArithmeticError LookupError EnvironmentError Raised Exceptions AssertionError AttributeError EOFError FloatingPointError GeneratorExit IOError ImportError IndexError KeyError KeyboardInterrupt MemoryError NameError NotImplementedError

For example: >>> try: ... Python Exception Message exception TimeoutError¶ Raised when a system function timed out at the system level. For example, when trying to reference an attribute that does not exist: class NoAttributes(object): pass o = NoAttributes() print o.attribute $ python exceptions_AttributeError.py Traceback (most recent call last): File "exceptions_AttributeError.py", line https://docs.python.org/2.7/tutorial/errors.html Good parallels with the talk linked in the comment on the OP's question: stackoverflow.com/questions/1319615/… –Bodhi Apr 9 '15 at 0:16 "That's an interesting constraint that future users may not

print "dealing with IndexError" ... Python Errno exception GeneratorExit¶ Raised when a generator or coroutine is closed; see generator.close() and coroutine.close(). Handlers only handle exceptions that occur in the corresponding try clause, not in other handlers of the same try statement. Concrete exceptions 5.2.1.

  1. However, for historical reasons, OverflowError is sometimes raised for integers that are outside a required range.
  2. share|improve this answer edited Jun 13 '14 at 23:39 Jim Ferrans 17.7k74167 answered Apr 22 '12 at 18:18 frnknstn 2,3321912 4 It looks like you shouldn't inherit from base exception.
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  5. Base classes¶ The following exceptions are used mostly as base classes for other exceptions.
  6. This must be either an exception instance or an exception class (a class that derives from Exception).

Python Exception Message

has the same meaning: assert , The line above can be "read" as: If evaluates to False, an exception is raised and will be output. http://stackoverflow.com/questions/1319615/proper-way-to-declare-custom-exceptions-in-modern-python except Exception as inst: ... Python Custom Exception The errno and strerror attributes are also None when the instance was created with other than 2 or 3 arguments. Python Raise Valueerror Look at the following example, which asks the user for input until a valid integer has been entered, but allows the user to interrupt the program (using Control-C or whatever

The Python Software Foundation is a non-profit corporation. http://vealcine.com/python-exception/python-io-error.php print "division by zero!" ... If an exception occurs which does not match the exception named in the except clause, it is passed on to outer try statements; if no handler is found, it is [email protected]:~/tmp$ python finally2.py Your number: 0 Infinity There may or may not have been an exception. Python Exception Class Methods

The following exceptions are used as warning categories; see the warnings module for more information. import module_does_not_exist $ python exceptions_ImportError_nomodule.py Traceback (most recent call last): File "exceptions_ImportError_nomodule.py", line 12, in import module_does_not_exist ImportError: No module named module_does_not_exist 2. All user-defined exceptions should also be derived from this class. this contact form Corresponds to errno EISDIR.

exception StandardError¶ The base class for all built-in exceptions except StopIteration, GeneratorExit, KeyboardInterrupt and SystemExit. StandardError itself is derived from Exception. Python Exception Stack Trace If the exception class is derived from the standard root class BaseException, the associated value is present as the exception instance's args attribute. When it is not handled, the Python interpreter exits; no stack traceback is printed.

That is the general rule.

Under Windows, if the winerror constructor argument is an integer, the errno attribute is determined from the Windows error code, and the errno argument is ignored. See also exceptions The standard library documentation for this module. In real world applications, the finally clause is useful for releasing external resources (such as files or network connections), regardless of whether the use of the resource was successful. 8.7. Python Attributeerror Object Has No Attribute This program will ask the user to enter a number until they guess a stored number correctly.

exception UnicodeError¶ Raised when a Unicode-related encoding or decoding error occurs. The default str() and repr() methods in Exception seem to do a good job of printing out any arguments passed into the MyException() constructor. Starting with Python 2.5, string exceptions result in a DeprecationWarning, and support for string exceptions will be removed in the future. navigate here Exception hierarchy¶ The class hierarchy for built-in exceptions is: BaseException +-- SystemExit +-- KeyboardInterrupt +-- GeneratorExit +-- Exception +-- StopIteration +-- StopAsyncIteration +-- ArithmeticError | +-- FloatingPointError | +-- OverflowError |

This exception is always defined, but can only be raised when Python is configured with the --with-fpectl option, or the WANT_SIGFPE_HANDLER symbol is defined in the pyconfig.h file. print type(inst) # the exception instance ... encoding¶ The name of the encoding that raised the error. reason¶ A string describing the specific codec error.

EOFErrorRaised when there is no input from either the raw_input() or input() function and the end of file is reached. Errors detected during execution are called exceptions and are not unconditionally fatal: you will soon learn how to handle them in Python programs.