[Tutor] create 1000 000 variables

[Michael P. Reilly]

Good.  But one VERY important point to note is that that you are not working
with "variables" here.  You are working with members of a class instance.
This is a very different beast.  You could just use getattr(), setattr() and
delattr() for these.

But continuing... you might want to think about this in a step back.  Each
of the self.hN and self.in_hN have something in common and they all have the
same behavior.  That sounds a lot like a job for "object oriented
programming", no?  We can create a class that look and acts like a list
(like hN), but is only active if we have set it (if in_hN is True).

Actually, because of the structure of the SGML code, "BAD CODE1" isn't quite
the "bad code", the "handle_data" code is actually worse.  The reason "BAD
CODE1" looks bad is not because of your code, but because SGMLParser forces
you to create so many methods in the subclass.  There are no "start_hN" and
"end_hN" catch-all methods available.  For this reason, I made only a minor
change to the "start_hN" and "end_hN" methods, but changed the reset and
handle_data methods quite a bit.

class HeaderCapture:
    def __init__(self, contents=[]):
        self.contents = contents[:] # copy
        self.deactivate()
    def append(self, item):
        # could raise an exception, but for now, ignore
        if self.active:
            self.contents.append(item)
    def __len__(self):
        return len(self.contents)
    def __getitem__(self, idx):
        return self.contents[idx]
    def activate(self):
        self.active = True
    def deactivate(self):
        self.active = False
...
class Lister(SGMLParser):

    def reset(self):
        SGMLParser.reset(self)
        self.headers = {
            'h1': HeaderCapture(),
            'h2': HeaderCapture(),
            'h3': HeaderCapture(),
            'h4': HeaderCapture(),
            'h5': HeaderCapture(),
            'h6': HeaderCapture(),
        }

    def handle_data(self, text):
        # only one would be active, but legally, two could
        for hc in self.headers.values():
            hc.append(text)  # if not active, ignore

    def start_h1(self, attrs):
        self.headers['h1'].activate()
    def end_h1(self):
        self.headers['h1'].deactivate()
    def start_h2(self, attrs):
        self.headers['h2'].activate()
    def end_h2(self):
        self.headers['h2'].deactivate()
    def start_h3(self, attrs):
        self.headers['h3'].activate()
    def end_h3(self):
        self.headers['h3'].deactivate()
    def start_h4(self, attrs):
        self.headers['h4'].activate()
    def end_h4(self):
        self.headers['h4'].deactivate()
    def start_h5(self, attrs):
        self.headers['h5'].activate()
    def end_h5(self):
        self.headers['h5'].deactivate()
    def start_h6(self, attrs):
        self.headers['h6'].activate()
    def end_h6(self):
        self.headers['h6'].deactivate()

On 7/15/06, Сергій <kyxaxa at gmail.com> wrote:
>
>  But again, like others have suggested, you should rethink your problem
> > and your solution before starting down your path.  What are you really
> > capturing?
> >
>
> Rethink problem...
> I try to use sgmllib - get all info tagged in "h1"... "h6"
> I've created file lister.py:
>
> "from sgmllib import SGMLParser
>
> class Lister(SGMLParser):
>
>  def reset(self):
>   SGMLParser.reset(self)
>   self.h1 = []
>   self.h2 = []
>   self.h3 = []
>   self.h4 = []
>   self.h5 = []
>   self.h6 = []
>
>   self.in_h1 = False
>   self.in_h2 = False
>   self.in_h3 = False
>   self.in_h4 = False
>   self.in_h5 = False
>   self.in_h6 = False
>
>  def handle_data(self, text):
>   if self.in_h1 == True:
>    self.h1.append(text)
>   elif self.in_h2 == True:
>    self.h2.append(text)
>   elif self.in_h3 == True:
>    self.h3.append(text)
>   elif self.in_h4 == True:
>    self.h4.append(text)
>   elif self.in_h5 == True:
>    self.h5.append(text)
>   elif self.in_h6 == True:
>    self.h6.append(text)
>
> #AND NOW "BAD CODE1":
>
>  def start_h1(self, attrs):
>   self.in_h1 = True
>
>  def end_h1(self):
>   self.in_h1 = False
>
>  def start_h2(self, attrs):
>   self.in_h2 = True
>
>  def end_h2(self):
>   self.in_h2 = False
>
>  def start_h3(self, attrs):
>   self.in_h3 = True
>
>  def end_h3(self):
>   self.in_h3 = False
>
>  def start_h4(self, attrs):
>   self.in_h4 = True
>
>  def end_h4(self):
>   self.in_h4 = False
>
>  def start_h5(self, attrs):
>   self.in_h5 = True
>
>  def end_h5(self):
>   self.in_h5 = False
>
>  def start_h6(self, attrs):
>   self.in_h6 = True
>
>  def end_h6(self):
>   self.in_h6 = False
>
> "
>
> And now I want to print all text in this tags.
>
> file use_lister.py:
>
> "
>
> import urllib, lister
>
> f = open('_1.html', 'r')
> text = f.read()
> f.close()
>
> parser = urllister.Lister()
> parser.feed(text)
> parser.close()
>
> #AND NOW "BAD CODE2":
>
> Show_step('h1')
> for i in parser.h1:
>   print i
>
> Show_step('h2')
> for i in parser.h2:
>   print i
>
> Show_step('h3')
> for i in parser.h3:
>   print i
>
> Show_step('h4')
> for i in parser.h4:
>   print i
>
> Show_step('h5')
> for i in parser.h5:
>   print i
>
> Show_step('h6')
> for i in parser.h6:
>   print i
>
> "
>
>
>
> And I don't like this "BAD CODE1" and "BAD CODE2"
>
> How to rewrite bad codes???
>
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> http://mail.python.org/mailman/listinfo/tutor
>
>
>


-- 
There's so many different worlds,
So many different suns.
And we have just one world,
But we live in different ones.
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