Thanks for the reply, Grant. I am not doing things like that - I am just trying to clear up in my mind the Python concepts.
I understand it now. Grant Edwards wrote: > On 2006-09-13, John Henry <[EMAIL PROTECTED]> wrote: > > Thanks for the reply, both to Laszlo and Steve. > > > > Okay, I understand what you're saying. > > > > But what if I need to make a "pointer" to a simple variable. > > There's no such thing as a "simple variable". There are > mutable objects and immutable objects. Names are bound to > objects. > > x = 3 > > The name "x" is bound to an immutable integer object who's > value is 3. > > > For instance, in C: > > > > int i=1 > > int *j=&i > > > > *j = 2 > > print i > > > > and you get 2 printed. > > > > In Python, > > > > i=1 > > The name "i" is bound to an immutable integer object who's value is 1. > > > j=i > > The name "j" is bound to an immutable integer object who's > value is 1. That may or may not be the same object to which > "i" is bound. > > > j=2 > > Now the name "j" is bound to an immutable integer object who's > value is 2. Rebinding the name "j" to a different object has > no effect on the object to which "i" is bound. > > > print i > > > > and you get 1 printed. > > Because you've changed neither the object to which "i" is bound > nor the value of that object (you can't change the values of > integer objects). > > > So, if I understand you correctly, I must make the reference > > to a more elaborate representation. Like: > > > > i=[1,] > > j=i > > j[0]=2 > > print i > > > > in order to get 2 printed. > > > > Correct? > > I suppose, for some values of "correct". You've bound the > names "i" and "j" to the same mutable object, then mutated that > object. Afterwards "i" and "i" still refer to that mutated > object. > > That'll work as a rather clumsy imitation of the C code, but I > don't really see what it is you're trying to accomplish. Trying > to write C code using Python isn't going to be fun or productive[1]. > > When using Python, you should write Python code. ;) > > If you'll explain the actual problem you're trying solve for > which you think you need C-style "pointers", then somebody will > be happy to show you how that problem is solved using Python. > > [1] There are people here who probably think it fun, but only > as a brain-teaser. > > -- > Grant Edwards grante Yow! After THIS, let's go > at to PHILADELPHIA and have > visi.com TRIPLETS!! -- http://mail.python.org/mailman/listinfo/python-list
