Re: working with pointers

[Chris Cioffi]

Nope, numbers too.  When you do:

 

a = 4

 

You are storing a reference to the literal 4 in a. 
 

>>> a = 4
>>> dir(a)
['__abs__', '__add__', '__and__', '__class__', '__cmp__', '__coerce__', '__delattr__', '__
div__', '__divmod__', '__doc__', '__float__', '__floordiv__', '__getattribute__', '__getne
wargs__', '__hash__', '__hex__', '__init__', '__int__', '__invert__', '__long__', '__lshif
t__', '__mod__', '__mul__', '__neg__', '__new__', '__nonzero__', '__oct__', '__or__', '__p
os__', '__pow__', '__radd__', '__rand__', '__rdiv__', '__rdivmod__', '__reduce__', '__redu
ce_ex__', '__repr__', '__rfloordiv__', '__rlshift__', '__rmod__', '__rmul__', '__ror__', '
__rpow__', '__rrshift__', '__rshift__', '__rsub__', '__rtruediv__', '__rxor__', '__setattr
__', '__str__', '__sub__', '__truediv__', '__xor__']
>>>

 

Unlike a list, there is no way to alter the interger value of 4.

 

If we go further, and then do something like:

>>> b = a
>>> b
4
>>>

 

Both a and b refer to the same object, in this case the 4 object.

 

If you want a copy of the object check out the copy module.

 

Chris
 

On 31/05/05, Michael <[EMAIL PROTECTED]> wrote:

except numbers??

"Dave Brueck" <[EMAIL PROTECTED] > wrote in message
news:[EMAIL PROTECTED]
> Michael wrote:
> > sorry, I'm used to working in c++ :-p
> >
> > if i do
> > a=2
> > b=a
> > b=0
> > then a is still 2!?
> >
> > so when do = mean a reference to the same object
>
> Always.
>
> > and when does it mean make a copy of the object??
>
> Never.
>
> -Dave


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