Warnings¶ The following exceptions are used as warning categories; see the warnings module for more information. exception UnicodeError¶ Raised when a Unicode-related encoding or decoding error occurs. Note that because of the underlying memory management architecture (C's malloc() function), the interpreter may not always be able to completely recover from this situation; it nevertheless raises an exception For functions that involve two file system paths (such as os.rename()), filename2 corresponds to the second file name passed to the function. http://caribtechsxm.com/python-exception/python-io-error-exception.php
The built-in exception classes can be sub-classed to define new exceptions; programmers are encouraged to at least derive new exceptions from the Exception class and not BaseException. If you are looking for examples that work under Python 3, please refer to the PyMOTW-3 section of the site. Built-in Exceptions¶ Exceptions should be class objects. exception ImportWarning¶ Base class for warnings about probable mistakes in module imports. view publisher site
The try statement can be followed by a finally clause. import unittest class AssertionExample(unittest.TestCase): def test(self): self.failUnless(False) unittest.main() $ python exceptions_AssertionError_unittest.py F ====================================================================== FAIL: test (__main__.AssertionExample) ---------------------------------------------------------------------- Traceback (most recent call last): File "exceptions_AssertionError_unittest.py", line 17, in test self.failUnless(False) AssertionError: False In user defined base classes, abstract methods should raise this exception when they require derived classes to override the method. This attribute is available when using the buffered I/O classes from the io module. exception ChildProcessError¶ Raised when an operation on a child process failed.
exception BufferError¶ Raised when a buffer related operation cannot be performed. Look at the following example, which tries to open a file and print its contents to the screen. Our next example shows a try clause, in which we open a file for reading, read a line from this file and convert this line into an integer. Python Filenotfounderror Base classes¶ The following exceptions are used mostly as base classes for other exceptions.
Because of the lack of standardization of floating point exception handling in C, most floating point operations also aren't checked. Python Custom Exception socket) set for non-blocking operation. The associated value is a string indicating the type of the operands and the operation. https://docs.python.org/3/tutorial/errors.html New in version 2.2: Previously known as the weakref.ReferenceError exception.
User code can raise built-in exceptions. Python Exception Class Methods DeprecationWarning Used for features no longer being maintained. Please enter an integer: 42.0 No valid integer! So make sure that you call it properly: Let's assume that you saved this program as "exception_test.py".
Exception hierarchy Previous topic 5. The built-in exception classes can be subclassed to define new exceptions; programmers are encouraged to derive new exceptions from the Exception class or one of its subclasses, and not from Python Exceptions List For example: for arg in sys.argv[1:]: try: f = open(arg, 'r') except IOError: print('cannot open', arg) else: print(arg, 'has', len(f.readlines()), 'lines') f.close() The use of the else clause is better Python Exception Message After having printed the text of the print statement, the execution does another loop.
The previous example is nearly the same as: import sys file_name = sys.argv text =  try: fh = open(file_name, 'r') except IOError: print('cannot open', file_name) else: text = fh.readlines() fh.close() http://caribtechsxm.com/python-exception/python-name-error-exception.php If a generator function defined in the presence of a from __future__ import generator_stop directive raises StopIteration, it will be converted into a RuntimeError (retaining In this case, you have to call it with python exception_test.py integers.txt If you don't want this behaviour, just change the line "file_name = sys.argv" to "file_name = 'integers.txt'". except statement has an optional else clause. Python Raise Valueerror
exception OSError¶ This exception is raised when a system function returns a system-related error, including I/O failures such as "file not found" or "disk full" (not for illegal argument types or exception SyntaxError¶ Raised when the parser encounters a syntax error. converting KeyError to AttributeError, while leaving the old exception available in __context__ for introspection when debugging. this content The associated value is an error message that includes the name that could not be found.
exception IsADirectoryError¶ Raised when a file operation (such as os.remove()) is requested on a directory. Python Errno except ValueError: ... Here are the changes between Python 2.7, 3.2, 3.3 and 3.4 (dev)  I enclosed 3.4 because its documentation of OSError says "Changed in version 3.4.", but I cannot see the
OS exceptions¶ The following exceptions are subclasses of OSError, they get raised depending on the system error code. Raising Exceptions¶ The raise statement allows the programmer to force a specified exception to occur. Python Course HomePython 2 TutorialPython 3 TutorialAdvanced TopicsNumerical PythonTkinter TutorialContact Python 3 Tutorial The Origins of PythonStarting with Python: The Interactive ShellExecuting a ScriptIndentationData Types and VariablesOperatorsSequential Data Types: Lists and Python Attributeerror Object Has No Attribute The errno attribute is then an approximate translation, in POSIX terms, of that native error code.
exception UnicodeTranslateError¶ Raised when a Unicode-related error occurs during translating. Starting with Python 2.5, string exceptions result in a DeprecationWarning, and support for string exceptions will be removed in the future. It directly inherits from BaseException instead of Exception since it is technically not an error. have a peek at these guys This attribute is available when using the buffered I/O classes from the io module. exception ChildProcessError¶ Raised when an operation on a child process failed.
with_traceback(tb)¶ This method sets tb as the new traceback for the exception and returns the exception object. But there is another way to use it as well. This is a subclass of SyntaxError. Instances of this class have attributes filename, lineno, offset and text for easier access to the details.
This allows the exception to properly propagate up and cause the interpreter to exit. exception NotImplementedError¶ This exception is derived from RuntimeError. The associated value is a string indicating the type of the operands and the operation. This is a subclass of SyntaxError.
exception ImportWarning¶ Base class for warnings about probable mistakes in module imports. print(type(inst)) # the exception instance ... See PEP 3151 - Reworking the OS and IO exception hierarchy: While some of these distinctions can be explained by implementation considerations, they are often not very logical at a higher Built-in Exceptions lists the built-in exceptions and their meanings. 8.3.
Under Windows, the winerror attribute gives you the native Windows error code. Hot Network Questions Differentiation of sine in Fourier domain Prove sets equality. exception TabError¶ Raised when indentation contains an inconsistent use of tabs and spaces. In addition to those of OSError, BlockingIOError can have one more attribute: characters_written¶ An integer containing the number of characters written to the stream before it blocked.
Navigation index modules | next | previous | Python v3.1.5 documentation » The Python Standard Library » 6. exception UnicodeEncodeError¶ Raised when a Unicode-related error occurs during encoding. python exception python-2.x share|improve this question edited Mar 30 '15 at 13:44 asked Mar 30 '15 at 13:42 Niklas R 4,6771042105 4 Changed in version 3.3: EnvironmentError, IOError, WindowsError, VMSError,