Peterbe.com

If you're into Zope python product stuff, read on, otherwise don't bother.

Thanks to Brian Lloyd (Zope corp) and Florent Guillaume (Nuxeo) I now know how to set security declarations on a class outside the class. It doesn't work like a normal python class (new or old style) which was a bit of a surprise. This is how you do it in a "normal" python class:

class _Z:
  def __init__(self):
      self.z = "Z"
  def declareProtected(self, *a,**k):
      print "++declare something+"

def foo():
  print "I'm being called"
  return _Z()

class A:
  security=foo()
  def __init__(self):
      pass
A.security.declareProtected("foo")

Had a quick play with Yahoo!'s Inbound Links API today. You use their web services API to check which other URLs a URL is linked to from. This can come in handy if you want to know which other sites make a link to your article. Googleblog is using this (obviously not by using the Yahoo! API); look at this blog post for example and scroll to the end of the text.

The inspiration came from Fredrik Lundh's term extraction example that I'm actually now use in a production site. So I basically took Fredriks code and modified it for Inbound Links.

I need to create a Zope index for a ZCatalog that is KeywordIndex. A KeywordIndex is a list (array if you like) that is used to describe some data. For example, if the data is "Peter is a Swedish Londoner", the the keywords are ("peter", "swedish", "londoner"). What about if the data you want to create an index of is a filename like "NameLog.txt" or "holiday-00412-juli-05.jpg". I've now quickly written a little something that seems to do a decent job. It splits the filenames (these are filenames only and no paths) by caMel structure, dot (.), underscore (_), dash (-) and digits.

If you want to play with my little script, have a look at filenamesplitter.py If you open that script you'll see that it tests a whole bunch of filenames (taken from the Demo issuetracker) and if you want to see what this the result is, here it is:

Last night I wrote a little function that tries to show dates cleverly by comparing the date with todays date, it formats the date differently.

If the date is today is just says "Today 10:00" and for yesterday it says "Yesterday 10:00". If it's within a week it shows is like this "Thursday 10:00". If the date is older than about 30 days it skips the time part and just shows "13-May 2005" and if anything else (ie. > 7 and < 30 days) it shows the whole thing like this "13-Oct 2005 10:00".

What do you think about this? ...from a usability/accessability point of view. One counter argument I have against this is that if you print off a page where it says "Today 12:22" and leave that printed paper for a few days, what "Today" means will change.

To demonstrate it, I've put together a little demo page so that you can get a feel for how it works. Please let me know what you think.

Tonight I need a little function that let me define a list of whitelisted email address and a list of blacklisted email address. This is then "merged" in a function called acceptOriginatorEmail(emailaddress) which is used to see if a particular email address is acceptable.

I've never written something like this before so I had to reinvent the wheel and guess my way towards a solution. My assumptions are that you start with whitelist and return True on a match on the blacklist, then you check against the blacklist and return False on a match and default to True if no match is made.

This makes it possible to define which email addresses should be accepted and which ones should be rejected like this:

whitelist = ('*@peterbe.com', 'bill.gates@microsoft.com')
blacklist = ('*@microsoft.com')

To some Python users this is old-school old-news stuff but since I've never used it before I found it worth mentioning.

I have a script that scans a rather large tree of folders filled with files. None of the folders have the same name but they can mistakably contain the same files eg:

folder XYZ-2005-11-27/
   email1.bin
   email2.bin
folder CBA-2005-07-10/
   email1.bin
   email2.bin

Sometimes two different folders contain the same file names exactly. Sometimes, the file sizes as equal too. But in some of those cases, even though the file sizes and names are the same they are different files. But! If they are the same files just in different locations I want to find them. How to do that?

I've just uploaded my second Python Cookbook recipe. It's unfortunately not rocket science but it's application is potentially very useful. With this little function you can generate the next number in a string that contains at least one number.

The mini unittest is quite interesting perhaps:

$ python increment_strings.py
from 10dsc_0010.jpg to 10dsc_0011.jpg
from dsc_9.jpg to dsc_10.jpg
from 0000001.exe to 0000002.exe
from ref-04851 to ref-04852

I've been playing around with Reverend a bit on getting it to correctly guess appropriate "Sections" for issues on the Real issuetracker. What I did was that I downloaded all 140 issuetexts and their "Sections" attribute which is a list (that is often of length 1). From list dataset I did a loop over each text and the sections within it (skipped the default section General) so something like this:

data = ({'sections':['General','Installation'], 
         'text':"bla bla bla..."}
        {'sections':['Filter functions'], 
         'text':"Lorem ipsum foo bar..."}
        ...)
for item in data:
    secs = [each for each item['sections'] if each != 'General']
    for section in secs:
        guesser.train(section, item['text'])

At the moment I'm not running Squid for this site but if experimentation time permits I'll have it running again soon. One thing I feel uneasy about is how to "manually" purge cached pages that needs to be updated. For example, if you read this page (and it's cached for one hour) and post a comment, then I'd like to re-cache this page with a purge. Setting a HTTP header could be something but that I would only be able to do on the page where you have this in the URL:

?msg=Comment+added

which, because of the presence of a querystring, is not necessarily cached anyway. The effect is that as soon as the "?msg=Comment+added" is removed from the URL, the viewer will see the page as it was before she posted her comment. squidclient might be the solution. ...sort of.

Some Ruby (the programming language) blogger has tried to implement the Edit-Distance algorithm in three different ways in both Python and in Ruby. His conclusion is more steered towards the difference between the algorithms and not so much the language. I guess that's fair because the implementation might be done better in Python than it was in Ruby. But, please notice that this is a Ruby coder and yet his Python implementations are always faster.

A quick glance tells me that the Python programs run about 3 times as fast as the Ruby ones. See the benchmarks