Training, Open Source Programming Languages

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Our email: info@wellho.net • Phone: 01144 1225 708225

 
For 2021 - online Python 3 training - see ((here)).

Our plans were to retire in summer 2020 and see the world, but Coronavirus has lead us into a lot of lockdown programming in Python 3 and PHP 7.
We can now offer tailored online training - small groups, real tutors - works really well for groups of 4 to 14 delegates. Anywhere in the world; course language English.

Please ask about private 'maintenance' training for Python 2, Tcl, Perl, PHP, Lua, etc.
Command line parameter handling in Python via the argparse module

A new example from the Python course just completed - looking at command line parameters through the argparse module from the standard Python library (2.7 and 3.2 onwards), and XML handling through the xml.etree.ElementTree module (2.5 onwards)

Here's code setting up an argument parser:

  parser = argparse.ArgumentParser()
  parser.add_argument('-a', '--all', action='store_true', help='Show all elements')
  parser.add_argument('-r', '--root', action='store_true', help='Show elements at root level')
  parser.add_argument('-v', action='store_true', help='Verbose')
  parser.add_argument('sourcefile', nargs=1, help='File to parse')
  args = parser.parse_args()


And by default, -h and --help are provided:

  munchkin:cambx grahamellis$ ./xmlparserdemo -h 6_context.xml 
  usage: xmlparserdemo [-h] [-a] [-r] [-v] sourcefile
  
  positional arguments:
    sourcefile  File to parse
  
  optional arguments:
    -h, --help  show this help message and exit
    -a, --all   Show all elements
    -r, --root  Show elements at root level
    -v          Verbose
  


Parameters are named within the object returned by the parser, so:

  if args.v:
    print("Running in verbose mode on file %s " % args.sourcefile[0])


And usage lines generated if the program is run with incorrect arguments:

  munchkin:cambx grahamellis$ ./xmlparserdemo -v -all 6_context.xml 
  usage: xmlparserdemo [-h] [-a] [-r] [-v] sourcefile
  xmlparserdemo: error: argument -a/--all: ignored explicit argument 'll'


Complete program using this code [here] ... the program goes on to handle XML data - there's a sample XML file [here].
(written 2015-12-08, updated 2015-12-09)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
Y115 - Additional Python Facilities
  [183] The elegance of Python - (2005-01-19)
  [208] Examples - Gadfly, NI Number, and Tcl to C interface - (2005-02-10)
  [239] What and why for the epoch - (2005-03-08)
  [463] Splitting the difference - (2005-10-13)
  [663] Python to MySQL - (2006-03-31)
  [672] Keeping your regular expressions simple - (2006-04-05)
  [753] Python 3000 - the next generation - (2006-06-09)
  [901] Python - listing out the contents of all variables - (2006-10-21)
  [1043] Sending an email from Python - (2007-01-18)
  [1136] Buffering output - why it is done and issues raised in Tcl, Perl, Python and PHP - (2007-04-06)
  [1149] Turning objects into something you can store - Pickling (Python) - (2007-04-15)
  [1305] Regular expressions made easy - building from components - (2007-08-16)
  [1336] Ignore case in Regular Expression - (2007-09-08)
  [1337] A series of tyre damages - (2007-09-08)
  [1876] Python Regular Expressions - (2008-11-08)
  [2407] Testing code in Python - doctest, unittest and others - (2009-09-16)
  [2435] Serialization - storing and reloading objects - (2009-10-04)
  [2462] Python - how it saves on compile time - (2009-10-20)
  [2655] Python - what is going on around me? - (2010-02-28)
  [2721] Regular Expressions in Python - (2010-04-14)
  [2745] Connecting Python to sqlite and MySQL databases - (2010-04-28)
  [2746] Model - View - Controller demo, Sqlite - Python 3 - Qt4 - (2010-04-29)
  [2764] Python decorators - your own, staticmethod and classmethod - (2010-05-14)
  [2765] Running operating system commands from your Python program - (2010-05-14)
  [2786] Factory methods and SqLite in use in a Python teaching example - (2010-05-29)
  [2790] Joining a MySQL table from within a Python program - (2010-06-02)
  [3089] Python regular expressions - repeating, splitting, lookahead and lookbehind - (2010-12-17)
  [3442] A demonstration of how many Python facilities work together - (2011-09-16)
  [3469] Teaching dilemma - old tricks and techniques, or recent enhancements? - (2011-10-08)
  [4085] JSON from Python - first principles, easy example - (2013-05-13)
  [4211] Handling JSON in Python (and a csv, marshall and pickle comparison) - (2013-11-16)
  [4298] Python - an interesting application - (2014-09-18)
  [4439] Json is the new marshall, pickle and cPickle / Python - (2015-02-22)
  [4451] Running an operating system command from your Python program - the new way with the subprocess module - (2015-03-06)
  [4536] Json load from URL, recursive display, Python 3.4 - (2015-10-14)
  [4709] Some gems from Intermediate Python - (2016-10-30)

Y108 - Python - String Handling
  [324] The backtick operator in Python and Perl - (2005-05-25)
  [496] Python printf - (2005-11-15)
  [560] The fencepost problem - (2006-01-10)
  [773] Breaking bread - (2006-06-22)
  [903] Pieces of Python - (2006-10-23)
  [943] Matching within multiline strings, and ignoring case in regular expressions - (2006-11-25)
  [954] Splitting Pythons in Bradford - (2006-11-29)
  [970] String duplication - x in Perl, * in Python and Ruby - (2006-12-07)
  [1110] Python - two different splits - (2007-03-15)
  [1195] Regular Express Primer - (2007-05-20)
  [1517] Python - formatting objects - (2008-01-24)
  [1608] Underlining in Perl and Python - the x and * operator in use - (2008-04-12)
  [2284] Strings as collections in Python - (2009-07-12)
  [2406] Pound Sign in Python Program - (2009-09-15)
  [2692] Flexible search and replace in Python - (2010-03-25)
  [2780] Formatted Printing in Python - (2010-05-25)
  [2814] Python - splitting and joining strings - (2010-06-16)
  [3090] Matching to a string - what if it matches in many possible ways? - (2010-12-17)
  [3218] Matching a license plate or product code - Regular Expressions - (2011-03-28)
  [3349] Formatting output in Python through str.format - (2011-07-07)
  [3468] Python string formatting - the move from % to str.format - (2011-10-08)
  [3796] Backquote, backtic, str and repr in Python - conversion object to string - (2012-07-05)
  [3886] Formatting output - why we need to, and first Python example - (2012-10-09)
  [4027] Collections in Python - list tuple dict and string. - (2013-03-04)
  [4152] Why are bus fares so high? - (2013-08-18)
  [4213] Formatting options in Python - (2013-11-16)
  [4307] Identifying and clearing denial of service attacks on your Apache server - (2014-09-27)
  [4360] Python - comparison of old and new string formatters - (2014-12-22)
  [4595] Python formatting update - including named completions - (2015-12-10)
  [4659] Prining a pound sign from Python AND running from the command line at the same time - (2016-03-03)

Y110 - Python - File Handling
  [114] Relative or absolute milkman - (2004-11-10)
  [1442] Reading a file multiple times - file pointers - (2007-11-23)
  [2011] Conversion of OSI grid references to Eastings and Northings - (2009-01-28)
  [2282] Checking robots.txt from Python - (2009-07-12)
  [2870] Old prices - what would the equivalent price have been in 1966? - (2010-07-14)
  [3083] Python - fresh examples from recent courses - (2010-12-11)
  [3465] How can I do an FTP transfer in Python? - (2011-10-05)
  [3558] Python or Lua - which should I use / learn? - (2011-12-21)
  [3764] Shell, Awk, Perl of Python? - (2012-06-14)
  [4438] Loving programming in Python - and ready to teach YOU how - (2015-02-22)
  [4663] Easy data to object mapping (csv and Python) - (2016-03-24)
  [4708] Scons - a build system in Python - building hello world - (2016-10-29)
  [4717] with in Python - examples of use, and of defining your own context - (2016-11-02)


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XML handling in Python - a new teaching example using etree
Some other Articles
Not standing as your local councillor
Call for help counting passengers - TransWilts, 12th to 14th December
XML handling in Python - a new teaching example using etree
Command line parameter handling in Python via the argparse module
A comparison of the public transport alternatives to the Royal United Hospital, Bath - from Melksham.
From single block to structure and object oriented programming
Progress on moving from Python 2 to Python 3 - training for both versions
Principles or a GUI and their practical application using wxPthon
What teach you in a week stays with you for a decade
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This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

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