>>> a = 2 >>> print('id(2) =', id(2)) id(2) = 1735878800 >>> print('id(a) =', id(a)) id(a) = 1735878800 >>>
A namespace containing all the built-in names is created when we start the Python interpreter and exists as long we don't exit. A name in Python is roughly analogous to a variable in just about any other language, but with a few extras. First of, because of Python’s dynamic nature, you can apply a name to just about anything.
Different namespaces can co-exist at a given time but are completely isolated.
This is the reason that built-in functions like id(), print() etc. are always available to us from any part of the program. Each module creates its own global namespace. You can of course give names to values.
>>> x = 9 >>> x = 'FTL' >>> x = [1,2,3,4,5,6,7]
Three different types of object at different instances. Functions are objects too, so a name can refer to them as well.
def func(): print ('This is a sample function') f = func
Although there are various unique namespaces defined, we may not be able to access all of them from every part of the program.
At any given moment, there are at least three nested scopes.
For example, the following code is perfectly legal in Python :
>>> var = 18 >>> var = "This is a sample string" >>> var = [2, 4, 6, 8, 10, 12, 14]
Here, the variable
a is in the global namespace. Variable
b is in the local namespace of
c is in the nested local namespace of
When we are in
c is local to us,
b is nonlocal and
a is global. We can read as well as assign new values to
c but can only read
>>> def outer_function(): global a a = 20 def inner_function(): global a a = 30 print('a =',a) inner_function() print('a =',a) a = 10 outer_function() >>> print('a =',a) a = 2 >>>