Dive Into Python by Mark Pilgrim

Author:Mark Pilgrim
Language: eng
Format: mobi, epub
Published: 2004-05-06T05:00:00+00:00

urllib2 is designed around URL handlers. Each handler is just a class that can define any number of methods. When something happens -- like an HTTP error, or even a 304 code -- urllib2 introspects into the list of defined handlers for a method that can handle it. You used a similar introspection in Chapter 9, XML Processing to define handlers for different node types, but urllib2 is more flexible, and introspects over as many handlers as are defined for the current request.

urllib2 searches through the defined handlers and calls the http_error_default method when it encounters a 304 status code from the server. By defining a custom error handler, you can prevent urllib2 from raising an exception. Instead, you create the HTTPError object, but return it instead of raising it.

This is the key part: before returning, you save the status code returned by the HTTP server. This will allow you easy access to it from the calling program.

Example 11.8. Using custom URL handlers

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.