Pythonic Pure Functions with Static Methods

lessons_pure_functions_static_methods.py

"""
Background:
Pure functions are functions that have no side effects and always perform 
the same computation resulting in the same ouput, given a set inputs. These
functions should only ever have access to the function scope. (1)

Static Methods (using @staticmethod decorator) can conceptually be treated as
"pure" since they do not have access to the either `cls` or `self` and must in
turn rely soley on input parameters to compute output.
"""

class MyName:
    def __init__(self, name:str):
        # initialize name
        self._name = self.capitalize(name)
        
    @staticmethod
    def capitalize(name:str) -> str: # no access to self or cls
        # pure, since it only ever peforms the same computation and only has access to function scope (name parameter)
        return name.upper()
   	
    @property
    def name(self) -> str:
        return self._name
    
my_name:MyName = MyName(name='Berto')
print(my_name.name) # -> BERTO 

caps_name = my_name.capitalize('Ernesto')
print(caps_name) # -> ERNESTO

# NOTE: in practice, you may not choose to encapsulate something as generic as capitalization.

# Sources:
# 1. Becoming Functional - Joshua Backfield