[Tutor] OOP and Python.. a gentle remark

[Asrarahmed Kadri]

Chris, you are right.
He (Alan) hits the bull's eye, always !!

Cheers...

Asrarahmed


On 10/25/06, Chris Hengge <pyro9219 at gmail.com> wrote:
>
> I dont know about the rest of you, but this thread posting from Alan
> cleared up some fuzzyness I've had about classes. /me is happier using this.
> instead of self. =D
>
> Great post!
>
> On 10/25/06, Alan Gauld <alan.gauld at btinternet.com> wrote:
> >
> >
> > "Asrarahmed Kadri" <ajkadri at googlemail.com> wrote
> > > Why is it necessary to explicity use self argument in the class
> > > functions
> >
> > Because Guido made it that way. :-)
> > But he did it for good reasons which others have pointed out already.
> >
> > Although languages like C++ and Java use implicit object references,
> > you can make them explicit with the 'this' keyword and most industrial
> > coding standards mandate that 'this' be used when referencing class
> > level variables inside methods. As in so many things Python simply
> > takes best practice and makes it mandatory.
> >
> > > the function? Isnt it ? (the use of 'self' keyword really confuses
> > > me. and
> >
> > If its the actual term 'self' then you can change it to anything
> > you prefer. C++/Java programmers might prefer 'this', some
> > others have used 'my':
> >
> > class C:
> >   def __init__(my, aValue):
> >      my.value = aValue
> >
> > is perfectly valid Python.
> >
> > > to make matter worse the variables can be accessed from outside teh
> > > class.
> > > Isnt it a violation of the OOP principle of ENCAPSULATION)
> >
> > The original OOP concept of encapsulation refers to the ability
> > to bind functions and data together in a single unit - a class or
> > object - and had nothing to do with data hiding which is the ability
> > to conceal the implementation details behind an API.
> >
> > It was only after C++ came out with its gazillion access
> > controls (public, private, protected, friend etc) that people started
> > to confuse data hiding and encapsulation. Many early OOP
> > languages (most Lisps included) do not offer explicit or strict
> > data hiding.
> >
> > > Also please let me know hwo can we declare
> > > PRIVATE VARIABLES in Python...??
> >
> > Why do you think you need them?
> > Do you frequently hit bugs because you couldn't resist the
> > urge to access members directly? While there can be problems
> > with badly behaved programmers on large projects, in the
> > things Python is typically used for its very rarely a problem.
> >
> > And it can add significantly to the complexity of the code
> > when you try to derive a class from one with private data.
> > Very few designers are sufficiently ppsychic to predict
> > exactly how all future users will want to modify their class!
> > The result is they supply get/set methods for all data which
> > are simply pass through methods. In doing so they
> > completely annull any benefit of private members and
> > introduce potential performance problems.
> >
> > HTH,
> > --
> > Alan Gauld
> > Author of the Learn to Program web site
> > http://www.freenetpages.co.uk/hp/alan.gauld
> >
> >
> > _______________________________________________
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> >
>
>
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>


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