Hi,

I'm a great scripter, but just learning programming (using Python).

I'm very much a newbie at this, so please be patient as I'm sure these will seem so basic a questions and may seem stupid to those experienced.

I'm reading a python book right now that has me thinking about variables.

As the title says, what does "x=5" really mean?

What is the "5" being assigned to? Is "x" considered an "instance" of "int?"

If I do this:

Code:

>>> class test(int):
    pass

>>> x=test(5)
>>> x
5
>>>

Then x here is an instance of class test(), a subclass of int.

But with int, you can do x=5.

If I do that after the above code, then x is no longer an instance of test() but is a variable of type int().

In the above, what is the 5 actually being assigned to in the instance of test()?

I have accessed it by defining a class and doing this just messing around:

Code:

>>> class test2(int):
    def value(self):
        print self
        self += 1
        print self

        
>>> x=test2(5)
>>> x
5
>>> x.value()
5
6
>>> x
5

Why doesn't the value of x change to 6 in the above example? I'm I "redefining" self in the value() method to no longer reflect what is self in the instance?

Also, can I "hijack" what x=5 means to to add my own methods, but it still behave like x=5. What I mean might be explained by this code:

Code:

#do whatever code here to "hijack" int()

>>> x=5
>>> x
5
>>> x.make_negative
>>> x
-5
>>> x=-2
>>> x
-2
>>> x.make_negative
>>> x
2

Or something like that?

If there is no way to do that and we go back to my original subclass definition, how do I change the value of the instance of the class to another value?

In:

Code:

>>> x=5
>>> x += 1
>>> x
6

How does the value of x become incremented internally? What magic is happening behind the scenes?

Say I want to do what is verboten in Python. Make in C-like incrementor like this.

Code:

>>> class Incrementor(int):
    def incAfter (self): # equivalent of x++
        #do whatever to access the value of instance
        return VALUE_OF_INSTANCE # as in x=Incrementor(5)
        VALUE_OF_INSTANCE += 1 # not quite sure how to do this to make it increment after returning the value (perhaps it is imporssible). Help here would be appreciated, too.
    def incBefore(self): # equivalent of ++x
        VALUE_OF_INSTANCE += 1
        return VALUE_OF_INSTANCE # as in x=Incrementor(5)

So that I could do something like this:

Code:

>>> x = Incrementor(5)
>>> x
5
>>> print x.incAfter()
5
>>> x
6
>>> print x.incBefore()
7
>>> x
7

Helping me with the concepts would really go a long way for me. Any help would be greatly appreciated.

Thankfully,
Narnie