Re: Unclear On Class Variables

[harold fellermann]

Hi Tim,
If you have
class Foo(object) :
        x = 0
        y = 1
foo = Foo()
foo.x # reads either instance or class attribute (class in this case)
foo.x = val # sets an instance attribute (because foo is instance not  
class)

Foo.x = val           # sets a class attribute
foo.__class.__x = val # does the same
this might be sometimes confusing. IMHO, the following is especially  
nasty:

>>> foo = Foo()
>>> foo.x += 1
>>>
>>> print foo.x
1
>>> print Foo.x
0
although the += operator looks like an inplace add it isn't.
it is just syntactic sugar for foo.x = foo.x + 1.
- harold -
On 13.01.2005, at 07:18, Tim Daneliuk wrote:
I am a bit confused.  I was under the impression that:
class foo(object):
        x = 0
        y = 1
means that x and y are variables shared by all instances of a class.
But when I run this against two instances of foo, and set the values
of x and y, they are indeed unique to the *instance* rather than the
class.
It is late and I am probably missing the obvious.  Enlightenment  
appreciated ...
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