Examples of __call__ usages in Python _python

This example describes the use of __call__ in Python and shares it for your reference. The specific methods are as follows:

Let's take a look at the following sample code:

#call. py A class is loaded in the case.
class Next:
  List = []
  
  def __init__ (Self,low,high): for
    Num in range (Low,high):
      self. List.append (Num * * 2)
  
  def __call__ (self,nu): Return
    self. LIST[NU]

If you use this:

b = Next (1,7)
print b.list
print B (2)

Then feedback is normal:

[1, 4, 9, +]
9

But if you use this:

b = Next
B (1,7)
print b.list
print B (2)
$python./call.py
[1, 4, 9,,,]

traceback ( Most recent called last):
 File "cal.py", line <module>
  print B (2) 
TypeError: __init__ () takes ex actly 3 Arguments (2 given)

__INIT__ is an initialization function that is executed when an instance of the class is generated.

And __call__ is an impersonation () call that needs to be applied on an instance, so this instance is naturally already executed __init__.

The following example that you have raised:

b = Next

This is not to create an instance, but to assign the class to a variable. So the next operation with B is the operation of the following class, which is actually:

Next (1,7)
print next.list
print next (2)

I hope this article will help you with your Python programming.