How does one write a function that increments a number?

[Brian van den Broek]

anonymousnerd at gmail.com said unto the world upon 25/06/2005 01:41:
> Wait... so this means it is impossible to write a function that
> increments an integer without turning the integer into a list?
> 

Well, one of these options will probably suit:

 >>> def increment_counter(data):
... 	data += 1
... 	return data
...
 >>> counter = 0
 >>> counter = increment_counter(counter)
 >>> counter
1

Or, if you only care about one counter, don't like the 
return/assignment form, and don't mind all the cool kids frowning on 
the use of global:


 >>> counter = 0
 >>> def increment_counter():
... 	global counter
... 	counter += 1
... 	
 >>> counter
0
 >>> increment_counter()
 >>> counter
1
 >>>


Nicest might be using a class, where you keep a clean namespace, and 
don't have the return/assignment form:

 >>> class My_class(object):
... 	def __init__(self):
... 		self.counter = 0
... 	def increment_counter(self):
... 		self.counter += 1
... 		
 >>> my_object = My_class()
 >>> my_object.counter
0
 >>> my_object.increment_counter()
 >>> my_object.counter
1
 >>>

This also lets you have multiple independent counters:

 >>> my_other_object = My_class()
 >>> my_other_object.counter
0
 >>> my_other_object.increment_counter()
 >>> my_other_object.increment_counter()
 >>> my_other_object.counter
2
 >>> my_object.counter
1
 >>>

Best,

Brian vdB