except ZeroDivisionError: ... finally: ... That's an interesting constraint that future users may not appreciate. Life on Smooth World How much are taxes for a postdoc in the United States? check over here
So what have we learned? If it is not a TypeError, then Python checks if it is an IndexError (B), etc. 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 Continuations are a powerful functional-programming tool and it can be useful to learn them. http://stackoverflow.com/questions/1319615/proper-way-to-declare-custom-exceptions-in-modern-python
Also, note that we're explicitly checking for TypeError, which is what would be raised if the coercion failed. Update: two answers have suggested overriding __init__, and __str__/__unicode__/__repr__. This is more easily and neatly achieved by just constructing a suitable exception beforehand and raising it when you need to: >>> oh_my_goodness = Exception("well, that rather badly didnt it?") >>>
Objects which, like files, provide predefined clean-up actions will indicate this in their documentation. return l[i] ... Visit this page to learn in detail about how you can handle exceptions in Python. ❮ Previous Page Next Page ❯ Want to learn more Python for Data Science? Python Error Vs Exception The Python community's approach to exceptions leads to cleaner code that's easier to read.
Sometimes you want an Exception that is very much like one of the built-in exceptions in every way, but it has some pre-determined message. Python Exception Class File name and line number are printed so you know where to look in case the input came from a script. 8.2. This seems like a pretty reasonable reaction. https://docs.python.org/2.7/tutorial/errors.html print("executing finally clause") ... >>> divide(2, 1) result is 2.0 executing finally clause >>> divide(2, 0) division by zero!
If such a function raises an Exception, then the traceback will help you find exactly what line of what file raised the error. >>> f3(1) Traceback (most recent call last): File Syntax For Generic Except Clause In Python comments powered by Disqus Copyright © 2014 - Jeff Knupp- Powered by Blug