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nested classes

Stefan Seefeld seefeld at sympatico.ca
Mon Jun 18 14:23:33 EDT 2001 
gbreed at cix.compulink.co.uk wrote:

> > What am I doing wrong ? The above is possibly a bit driven
> > by my C++ programming style. What is the python way of doing
> > this ?
> 
> You can get that to work in C++?  It looks strange to me, I'm
> sure you can't be trying to do what you think you're trying to
> do.  This is the nearest I can think of that works:

uh, what do *you* think that I'm trying to do, then ? :)

What I'm arguing about is a matter of name resolution. I sure
can open a scope 'A' in C++, insert a new scope 'B' into it,
and from within that access other symbols declared in scope 'A'.
In fact, I don't need to qualify them (i.e. 'foo' instead of 'A::foo'
for any symbol 'foo' in the scope 'A' is just fine) if I'm inside
that scope, no matter how deeply nested (of course, as long as there
are no ambiguities).



> 
> >>> class A:
> ...     prefix = 'usr/local'
> ...
> >>> class B(A):
> ...     datadir = A.prefix+'/share'
> ...
> >>> A.prefix
> 'usr/local'
> >>> B.datadir
> 'usr/local/share'

ok, that works because B derives from A, i.e. the definition of 'A'
is complete at the point where B's definition starts.

> >>> class A:
> ...     prefix = os.path.join('usr','local')
> ...
> >>> class B(A):
> ...     datadir = os.path.join(A.prefix, 'share')

good idea, thanks. the original 'prefix' stems from 'configure', i.e.
my python file 'foo.py' is generated from 'foo.py.in' by means of the
autotools (autoconf, configure, ...)

Thanks,
		Stefan
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