Beginning Python - From Novice to Professional

428 CHAPTER 22 ■ PROJECT 3: XML FOR ALL OCCASIONS
Creating HTML Pages
Now you’re ready to make the prototype. For now, let’s ignore the directories and concentrate
on creating HTML pages. You have to create a slightly embellished event handler that does
the following:
• At the start of each page element, opens a new file with the given name, and writes a suitable
HTML header to it, including the given title
• At the end of each page element, writes a suitable HTML footer to the file, and closes it
• While inside the page element, passes through all tags and characters without modifying
them (writes them to the file as they are)
• While not inside a page element, ignores all tags (such as website and directory
Most of this is pretty straightforward (at least if you know a bit about how HTML documents
are constructed). There are two problems, however, which may not be completely obvious.
First, you can’t simply “pass through” tags (write them directly to the HTML file you’re
building) because you are given their names only (and possibly some attributes). You have to
reconstruct the tags (with angle brackets and so forth) yourself.
Second, SAX itself gives you no way of knowing whether you are currently “inside” a page
element. You have to keep track of that sort of thing yourself (as we did in the HeadlineHandler
example). For this project, we’re only interested in whether or not to pass through tags and
characters, so we’ll use a Boolean variable called passthrough, which we’ll update as we enter
and leave the pages.
See Listing 22-2 for the code for the simple program.
Listing 22-2. A Simple Page Maker Script (pagemaker.py)
from xml.sax.handler import ContentHandler
from xml.sax import parse
class PageMaker(ContentHandler):
passthrough = False
def startElement(self, name, attrs):
if name == 'page':
self.passthrough = True
self.out = open(attrs['name'] + '.html', 'w')
self.out.write('\n')
self.out.write('%s\n' % attrs['title'])
self.out.write('\n')
elif self.passthrough:
self.out.write('')