**Good**:

defcreate_micro_brewery(name:str="Hipster Brew Co."):

defcreate_micro_brewery(name:str="Hipster Brew Co."):

slug= hashlib.sha1(name.encode()).hexdigest()

Flags tell your user that this function does more than one thing. Functions should do one thing. Split your functions if they are following different code paths based on a boolean.

Flags tell your user that this function does more than one thing. Functions

should do one thing. Split your functions if they are following different code

paths based on a boolean.

**Bad:**

**[⬆ back to top](#table-of-contents)**

A function produces a side effect if it does anything other than take a value in

and return another value or values. A side effect could be writing to a file,

modifying some global variable, or accidentally wiring all your money to a

stranger.

Now, you do need to have side effects in a program on occasion - for example, like

in the previous example, you might need to write to a file. In these cases, you

should centralize and indicate where you are incorporating side effects. Don't have

several functions and classes that write to a particular file - rather, have one

(and only one) service that does it.

The main point is to avoid common pitfalls like sharing state between objects

without any structure, using mutable data types that can be written to by anything,

and not centralizing where your side effects occur. If you can do this, you will be

happier than the vast majority of other programmers.

**Bad:**

name='Ryan McDermott'

defsplit_into_first_and_last_name() ->None:

global name

name= name.split()

split_into_first_and_last_name()

print(name)# ['Ryan', 'McDermott']

**Good:**

defsplit_into_first_and_last_name(name:str) ->None:

return name.split()

name='Ryan McDermott'

new_name= split_into_first_and_last_name(name)

print(name)# 'Ryan McDermott'

print(new_name)# ['Ryan', 'McDermott']

**[⬆ back to top](#table-of-contents)**