[Tutor] Const on Python

Alan Gauld alan.gauld at btinternet.com
Fri Mar 7 00:42:39 CET 2008

> Now coming back to your question, that you want a non-changeable 
> name,
> well, one can create such a beast, e.g.:
> def constant(value):
> ...
>class Test(object):
>     const_a = constant(123)
> This creates a member that can only be fetched, but not set or 
> deleted.

Only within constant. the member const_a can be changed
via simple assignment.

> But in practice, I personally never have seen a need for something 
> like
> this. You can always overcome the above constant. Btw, you can do 
> that
> in C++ privates too, worst case by casting around and ending up with 
> a
> pointer that points to the private element ;)

I've seen an even more mundane trick to bypass private(rather than 

#define private public
#define protected public
#include "someclass.h"

SomeClass c = new SomeClass;

c->someVar = 42;


I suppose you could avoid that by prefixing every classs definition 

#define private private
#define protected protected
class SomeClass{....};

But it illustrates the relative fragility of C++ apparently tight 
of names and visibility. And with a pointr to the right memory
location and a cast you can do just about anything...

In that respect I prefer the blatant openness of Python to the
perceived protection of C++

Alan G. 

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