Super-newbie syntax error question

[Cliff Wells]

On Sun, 28 Apr 2002 23:07:14 GMT
Charlie Wood wrote:

> I have some code that I've cobbled together, and have just introduced a
> syntax error. I've read through the docs, done lots of trial and error, and
> I'm left scratching my head. Any ideas?
> 
> Here's the code:
> 
>     def endElement(self, name):
>         if self._parent == "item":
>             if name == "title":
>                 self._title = self._text
>             elif name == "link":
>                 self._link = self._text
>             elif name == "description":
>                 self._descr = self._text
>             elif name == "category":
>                 self._category = self._text
>             elif name == "item":
>                 if not self._list_started:
>                     self._out.write("\n")
>                     self._list_started = 1
> 
>                 self._out.write('%s: %s\n%s\n%s\n\n' %
>                                 (self._category, self._title, self._descr,
> self._link))
> 
>     f = file("/article.txt", "w")
>     f.write('Category: %s\nTitle: %s\nDescription: %s\nLink: %s\n\n' %
>       (self._category, self._title, self._descr, self._link))
>     f.close()
> 
>                 self._title = None
>                 self._link = None
>                 self._descr = ""
>                 self._category = ""

Other people have addressed your syntax error, but I'd like to point out that
you may want to use a dictionary rather than assigning to attributes as this
could shorten your code quite a bit:

class SomeClass(...):
    def __init__(self, ...):
        self._initAttribs()
        ...

    def _initAttribs(self):
        """explicitly initialize dictionary since it isn't clear 
           whether all values will be set later"""
        self.attribs = {
            'category': '',
            'description': '',
            'title': None,
            'link': None
        }

    ...

    def endElement(self, name):
        if self._parent = "item":
            if name != "item":
                self.attribs[name] = self._text
            else:
                if not self._list_started:
                    self._out.write("\n")
                    self._list_started = 1
                self._out.write('%(category)s:'
                                '%(title)s\n'
                                '%(description)s\n'
                                '%(link)s\n\n' 
                                 % self.attribs)

                # unsure of the indentation level of this bit since it appears
                # to be incorrect in your original code (also note using "open"
                # rather than "file")
                f = open("/article.txt", "w")
                f.write('Category: %(category)s\n'
                        'Title: %(title)s\n'
                        'Description: %(description)s\n'
                        'Link: %(link)s\n\n'
                        % self.attribs)
                f.close()
                self._initAttribs()

Whether you can take this approach of course depends upon your particular
application, but whenever I see if/elif/else start to stretch out, I start
thinking "lookup table".  Not only does it eliminate long if/elif/else
constructs, but you can use it in format strings as well, which I find to be a
bit clearer.


-- 
Cliff Wells, Software Engineer
Logiplex Corporation (www.logiplex.net)
(503) 978-6726 x308  (800) 735-0555 x308