When you have more than one level of abstraction, your function is usually doing too

much. Splitting up functions leads to reusability and easier testing.

**Bad:**

def parse_better_js_alternative(code: str) -> None:

regexes = [

# ...

]

statements = regexes.split()

tokens = []

for regex in regexes:

for statement in statements:

# ...

ast = []

for token in tokens:

# Lex.

for node in ast:

# Parse.

**Good:**

def parse_better_js_alternative(code: str) -> None:

tokens = tokenize(code)

syntax_tree = parse(tokens)

for node in syntax_tree:

# Parse.

def tokenize(code: str) -> list:

REGEXES = [

# ...

]

statements = code.split()

tokens = []

for regex in REGEXES:

for statement in statements:

# Append the statement to tokens.

return tokens

def parse(tokens: list) -> list:

syntax_tree = []

for token in tokens:

# Append the parsed token to the syntax tree.

return syntax_tree

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

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:**

from pathlib import Path

def create_file(name: str, temp: bool) -> None:

if temp:

Path('./temp/' + name).touch()

else:

Path(name).touch()

**Good:**

from pathlib import Path

def create_file(name: str) -> None:

Path(name).touch()

def create_temp_file(name: str) -> None:

Path('./temp/' + name).touch()

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