Reading

• http://www.diveintopython.net/index.html

Language spec

• list of magic methods: http://www.rafekettler.com/magicmethods.html
• __get__, __getattr__, setattr: https://docs.python.org/2/howto/descriptor.html

Dependency management

• setup.py vs requirements.txt

ORM

• Mixin

Inheritance

• Multiple inheriance: order matters. first one determines which one is applied

Debugging

• Print complete error message when debugging in pdb

  import traceback; print "".join(traceback.format_exception_only(*__exception__))
  

Number format

• format number with 0 padding in the front

  'hello {0:03d} world {1:05d}'.format(11, 22)
  .zfill(3) will also work
  

Datetime

• Convert from UTC to other locales

  class Zone(tzinfo):
      def __init__(self,offset,isdst,name):
          self.offset = offset
          self.isdst = isdst
          self.name = name
      def utcoffset(self, dt):
          return timedelta(hours=self.offset) + self.dst(dt)
      def dst(self, dt):
              return timedelta(hours=1) if self.isdst else timedelta(0)
      def tzname(self,dt):
           return self.name
  PDT = Zone(-7,False,'PDT')
  print datetime.utcnow().strftime('%m/%d/%Y %H:%M:%S %Z')
  print 'PDT:',datetime.now(PDT).strftime('%m/%d/%Y %H:%M:%S %Z')
  

• Custom User Model: http://scottbarnham.com/blog/2008/08/21/extending-the-django-user-model-with-inheritance/

• .vimrc for Python: http://www.vex.net/~x/python_and_vim.html
• exec python script in vim: noremap :!python %

• __dict__: instance variables in a dictionary that belongs to the object. it contains all other attributes of the object. Each python object has a __dict__ atttribute which is a dictionary containing all other attributes. e.g. when you type self.attr python is actually doing self.__dict__['attr']. As you can imagine using a dictionary to store attribute takes some extra space & time for accessing it. However, when you use __slots__, any object created for that class won't have a __dict__ attribute. Instead, all attribute access is done directly via pointers.
• dir():"attributes, its class's attributes, and recursively the attributes of its class's base classes."
• Special methods such as __contains__ are only special when defined on the class, not on the instance (except in legacy classes in Python 2, which you should not use anyway). http://stackoverflow.com/questions/1022499/emulating-membership-test-in-python-delegating-contains-to-contained-object
• static methods vs. class methods: static methods are a func defined in a class body. class methods change with subclasses.
• decorators: syntax sugar. semantically equivalent to expanding it. http://www.artima.com/weblogs/viewpost.jsp?thread=240808
• install older version package: easy_install -m docutils==0.3.9
• profiling: http://stefaanlippens.net/python_profiling_with_pstats_interactive_mode
• encodings: http://docs.python.org/library/codecs.html#standard-encodings

• Decoding: interpret the string to unicode str.decode('utf8') from utf8 to unicode check http://farmdev.com/talks/unicode/ http://gomputor.wordpress.com/2008/09/22/convert-a-file-in-utf-8-or-any-encoding-with-python/
• Encoding(charset): encode string to charset chars str.encode('utf8') from unicode to utf8

    1 import sys
    2 
    3 s = 'abc123'
    4 print type(s)
    5 
    6 u = u'abc123'
    7 print type(u)
    8 
    9 print type(s.decode('ascii'))
   10 print type(s.encode('utf8'))
   11 
   12 print type(u.decode('ascii'))
   13 print type(u.encode('utf8'))
  
  output:
  < type 'str'>
  < type 'unicode'>
  < type 'unicode'>
  < type 'str'>
  < type 'unicode'>
  < type 'str'>
  

Web
• wsgi+web.py: template not found error. http://www.mail-archive.com/webpy@googlegroups.com/msg06797.html