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.
What is a universal superclass? Java / Perl / Python / Other OO languages
In any object oriented language, all objects will ultimately inherit from a base class supplied with the language, whether it's explicitly stated or not. That's because every class that you write will need that basic facilities to set up members (objects), and it's also useful to provide you with a handful of standard methods that will work for each and every object - either in their default form, or overridden if you want your class to do something a bit differently.
, everything inherits from the base class Object
- directly if you define your class without an extends
clause, or indirectly through the heirarcy that you mayhave chosen to set up. Methods provided include finalize
(a default destructor), getClass
to find out about the type of an object [use with care!], toString
which defines how an object is converted to a String, and equal
which is used to test whether two objects are considered to be equal. The latter two of these are methods that you'll often want to override in your own classes, and there's a new example on our web site [here]
's UNIVERSAL class includes methods isa
to see if an object is of a particular type (literally "is a"), can
to test whether a particular method can be run on an object, and DOES
to check whether an object can perform a paricular role.
(new style classes) you always inherit from an object:
>>> class Snake(object):
>>> spit = Snake()
And you'll find that you get a whole wide range of things (other objects - in Python everything is an object) provided to you by the object class:
>>> dir(spit) (written 2010-11-13)
['__class__', '__delattr__', '__dict__', '__doc__', '__format__', '__getattribute__',
'__hash__', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__',
'__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__']
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articlesJ710 - Java - Extending Classes and More 
Think about your design even if you don't use full UML - (2006-03-24) 
Comparison of Object Oriented Philosophy - Python, Java, C++, Perl - (2006-08-13) 
Final, Finally and Finalize - three special words in Java - (2007-02-05) 
What are factory and singleton classes? - (2007-06-04) 
An example of Java Inheritance from scratch - (2007-08-00) 
Java - using super to call a method in the parent class - (2008-01-10) 
Teaching Object Oriented Java with Students and Ice Cream - (2008-02-12) 
Java - a demonstration of inheritance on just one page - (2008-02-26) 
Calling base class constructors - (2008-10-03) 
Abstract Classes - Java - (2009-05-16) 
Abstract classes, Interfaces, PHP and Java - (2009-10-03) 
Tips for writing a test program (Ruby / Python / Java) - (2010-01-29) 
What methods are available on this Java object? - (2010-07-08) 
Splitting out code into name blocks for clarity and reusability - (2014-11-30) 
Changing what operators do on objects - a comparison across different programming languages - (2014-12-26) 
Philosophy behind object design - and how I applied in to a Java example - (2015-01-14) 
Java Inheritance example - group of classes - step by step - (2015-02-08) 
Objects - from physical to virtual or abstract - Java - (2015-02-10)J709 - Java - Class Access 
Who can use which access door? - (2006-09-21) 
Where is my Java class? - (2009-09-24) 
When should I use Java, Perl, PHP, or Python? - (2009-12-13) 
Private and Public - and things between - (2011-01-22) 
Accessing variables across subroutine boundaries - Perl, Python, Java and Tcl - (2015-01-18)
Some other Articles
Positively reforming the system - could it be done?Views of Melksham - November 2010Computer Graphics is fun - even if Java Applets are Old HatString handling - from first steps to practical examplesWhat is a universal superclass? Java / Perl / Python / Other OO languagesJava Beans, tag libraries and JSPs - what and why.After Course Resources - do we publish sample answers. Example from Java Exceptions module.Changing a Servlet - more that just editing and compilingGathering information - logging - with log4j. First steps.Least Common Ancestor - what is it, and a Least Common Ancestor algorithm implemented in Perl
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Comment by Graham Ellis
|Comment: "Yes ... my error. I said "all" when I should not have done ..."|
Visitor Ranking 3.5 (5=excellent, 1=poor)
Yes ... my error. I said "all" when I should not have done so, as the interitance from a standard base class does not apply in C++. C++ is rather different to the other OO languages we run courses on, as it's what I would describe as a low level language with an OO layer added on top of it. [#3891]Comment by Anon
"In any object oriented language, all objects will ultimately inherit from a base class supplied with the language, whether it's explicitly stated or not."
Wrong. C++ does not do this. [#3871]
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