Pieces of Python

From a most interesting Saturday which was spent doing a one on one session on thread, wxPython, etc - some Python snippets that provide unusual demos and hard-to-find answers:

The Backtic operator evaluates an expression and returns the result as a string

val1 = 16

val2 = 18

result = "The result is "+`val1 + val2`

print result

If you want to have various bits of code running at the same time you can use piping, or you can use threads, or you can use a client / server system via TCP/IP.

We have an example of Python threading and a python tcp/ip client and a simple python server all available on this web site. Piping is especially useful if you're containing / running an outside process on your machine, threads are useful where you're processing the same type of data in parallel many times over, and a client / server architecture is ideally suited to a logger and display application, with a server logging and one or more client, perhaps on remote computers, displaying.

The wxPython module provides an excellent GUI - in other words an excellent way to provide a user interface on the front of your Python code. However, there's a lack of good worked learning examples. I've just added more source code examples - linkable from our wxPython training course module. These examples were originally based on other published code, but have been extensively rearranged for clarity and commented.

The super call only works on new style classes!.

If you try to use "super" on old syle classes, you'll be told "TypeError: super() argument 1 must be type, not instance".

Old style classes ...

# old style classes



class thing:

   def __init__(self):

      pass



class specialthing(thing):

   def __init__(self):

      thing.__init__(self)



this = specialthing()

New style classes ...

# new style classes



class thing(object):

   def __init__(self):

      pass



class specialthing(thing):

   def __init__(self):

      super(specialthing,self).__init__()



this = specialthing()

What are new style classes? .... they're classes that are derived, directly or indirectly, from built in classes and they've been around since Python 2.2. As well as super, other new features include the ability to define static and class methods, rather than just a method in the same namespace. more details (external link)

We offer Python training courses. If you've just one or two people to be trained, our public courses which run every 2 or 3 months are going to be best value. For slightly larger groups, we'll run a private course at our centre. With 6 or more delegates all wanting to learn the same material at the same time, we'll come to you - you just provide a room and the students, we do the rest!
(written 2006-10-23, updated 2006-11-01) 2fe1

Associated topics are indexed under

Y108 - Python - String Handling
  [4027] Collections in Python - list tuple dict and string. - (2013-03-04)
  [3886] Formatting output - why we need to, and first Python example - (2012-10-09)
  [3796] Backquote, backtic, str and repr in Python - conversion object to string - (2012-07-05)
  [3469] Teaching dilemma - old tricks and techniques, or recent enhancements? - (2011-10-08)
  [3468] Python string formatting - the move from % to str.format - (2011-10-08)
  [3349] Formatting output in Python through str.format - (2011-07-07)
  [3218] Matching a license plate or product code - Regular Expressions - (2011-03-28)
  [3090] Matching to a string - what if it matches in many possible ways? - (2010-12-17)
  [2814] Python - splitting and joining strings - (2010-06-16)
  [2780] Formatted Printing in Python - (2010-05-25)
  [2765] Running operating system commands from your Python program - (2010-05-14)
  [2721] Regular Expressions in Python - (2010-04-14)
  [2692] Flexible search and replace in Python - (2010-03-25)
  [2406] Pound Sign in Python Program - (2009-09-15)
  [2284] Strings as collections in Python - (2009-07-12)
  [1876] Python Regular Expressions - (2008-11-08)
  [1608] Underlining in Perl and Python - the x and * operator in use - (2008-04-12)
  [1517] Python - formatting objects - (2008-01-24)
  [1195] Regular Express Primer - (2007-05-20)
  [1110] Python - two different splits - (2007-03-15)
  [970] String duplication - x in Perl, * in Python and Ruby - (2006-12-07)
  [954] Splitting Pythons in Bradford - (2006-11-29)
  [943] Matching within multiline strings, and ignoring case in regular expressions - (2006-11-25)
  [773] Breaking bread - (2006-06-22)
  [560] The fencepost problem - (2006-01-10)
  [496] Python printf - (2005-11-15)
  [463] Splitting the difference - (2005-10-13)
  [324] The backtick operator in Python and Perl - (2005-05-25)

Y112 - Python - Objects - Intermediate
  [4094] Python Properties - how and why - (2013-05-18)
  [4028] Really Simple Class and Inheritance example in Python - (2013-03-04)
  [3887] Inheritance, Composition and Associated objects - when to use which - Python example - (2012-10-10)
  [3524] Metaclasses (Python) and Metatables (Lua) - (2011-11-17)
  [3472] Static variables in functions - and better ways using objects - (2011-10-10)
  [3442] A demonstration of how many Python facilities work together - (2011-09-16)
  [3002] A list of special method and attribute names in Python - (2010-10-17)
  [2994] Python - some common questions answered in code examples - (2010-10-10)
  [2905] Defining static methods in Python - (2010-08-05)
  [2889] Should Python classes each be in their own file? - (2010-07-27)
  [2785] The Light bulb moment when people see how Object Orientation works in real use - (2010-05-28)
  [2764] Python decorators - your own, staticmethod and classmethod - (2010-05-14)
  [2722] Mixins example in Python - (2010-04-14)
  [2720] Multiple inheritance in Python - complete working example - (2010-04-14)
  [2717] The Multiple Inheritance Conundrum, interfaces and mixins - (2010-04-11)
  [2693] Methods that run on classes (static methods) in Python - (2010-03-25)
  [2485] How do I set up a constant in Python? - (2009-10-31)
  [2409] TypeError: super() argument 1 must be type, not classobj (Python) - (2009-09-18)
  [2368] Python - fresh examples of all the fundamentals - (2009-08-20)
  [1819] Calling base class constructors - (2008-10-03)
  [1661] Equality, sameness and identity - Python - (2008-05-31)
  [1644] Using a utility method to construct objects of different types - Python - (2008-05-17)
  [1217] What are factory and singleton classes? - (2007-06-04)
  [1146] __new__ v __init__ - python constructor alternatives? - (2007-04-14)
  [964] Practical polymorphism in action - (2006-12-04)
  [831] Comparison of Object Oriented Philosophy - Python, Java, C++, Perl - (2006-08-13)
  [656] Think about your design even if you don't use full UML - (2006-03-24)
  [477] Class, static and unbound variables - (2005-10-25)
  [383] Overloading of operators on standard objects in Python - (2005-07-19)
  [296] Using a Python dictionary as a holder of object attributes - (2005-04-30)

Y202 - Python on the Web
  [4089] Quick and easy - showing Python data hander output via a browser - (2013-05-15)
  [2365] Counting Words in Python via the web - (2009-08-18)
  [2238] Handling nasty characters - Perl, PHP, Python, Tcl, Lua - (2009-06-14)
  [1745] Moodle, Drupal, Django (and Rails) - (2008-08-08)
  [433] FTP - how to make the right transfers - (2005-09-01)
  [426] Robust checking of data entered by users - (2005-08-27)
  [237] Crossfertilisation, PHP to Python - (2005-03-06)

Y207 - wxPython
  [3139] Steering our Python courses towards wxPython, SQLite and Django - (2011-01-19)
  [3092] wxPython geometry - BoxSizer example - (2010-12-17)
  [3086] Sizers (geometry control) in a wxPython GUI - a first example - (2010-12-15)
  [3081] wxPython - simple example to add GUI to a server log file analysis - (2010-12-08)
  [2887] Snow Leopard and Python (that is OS X 10.6 and wxPython) - (2010-07-26)
  [2744] PyQt (Python and Qt) and wxPython - GUI comparison - (2010-04-28)
  [2013] wxPython - Introduction and sample - (2009-01-29)

Y302 - Python - Threads - What why and how
  [2489] Parallel Pinging, using Python Threads or Expect spawn lists - (2009-11-02)

5671

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