How do I check if a variable has gone up?

Question

here is some code. I want to make an if statement but only when a variable has increased

while True:
    a += 1

    if a ????               
        print('a has changed')


   

Answer 1

Here is an option.

while True:
    previous = a
    # do stuff
    a += 1

    if a != previous:               
        print('a has changed')

Answer 2

Here is a way you can do this:

while True:
    old_a = a #Create a variable for the old value of a 
    a += 1

    if a > old_a: #Check the condition if value of a has increased.              
        print('a has changed')

Answer 3

A more clever way using the python Observer pattern.

class observe_value_change():
   def __init__(self):
      self._initial = 1

   @property
   def position(self):
      return self._initial

   @position.setter
   def position(self, new_value):
      self._initial = new_value
      print("execute more code here!")
      print(self._initial)

To test

p = observe_value_change()
print(p.position)
p.position = 4

Explanation: When the value of position changes, it will call the position setter method otherwise it will not be called. So, the if block can be written inside the position setter method.