Naming and Binding
A name is a piece of text that is bound to an object. They are a reference to an object. Examples are function names, class names, module names, variables, etc.
Note: Names cannot reference other names, and assignment never creates a copy.
x = 1 # x is bound to 1
y = x # y is bound to VALUE of x
x = 2 # x is bound to 2
print(x, y) # 2 1y = x, the name y is being bound to the value of x which is 1. Neither x nor y are the 'real' name. The object 1 simply has multiple names. They are the exact same object.
>>> x = 1
x ━━ 1
>>> y = x
x ━━ 1
y ━━━┛
>>> x = 2
x ━━ 2
y ━━ 1You might think that the only way to bind a name to an object is by using assignment, but that isn't the case. All of the following work exactly the same as assignment:
•
import statements•
class and def•
for loop headers•
as keyword when used with except, import, and with• formal parameters in function headers
There is also del which has the purpose of unbinding a name.
More info
• Please watch Ned Batchelder's talk on names in python for a detailed explanation with examples
• Official documentation