Study Group: 巾凡哥出品 品質保證 python 06

List Comprehension

cities = ['Austin', 'Tacoma', 'Topeka', 'Sacramento', 'Charlotte']
{city: [0 for _ in range(7)] for city in cities}

function

• slash /
  • are positional-only

def fn(a, b, c, /):
    print(a, b, c)

fn(1, 2, 3) # <=== work
fn(1, 2, c=3) # <=== error
# ==========================

• Requiring argument to be named
  • In this situation, parameter age doesn’t have default value, so you must pass named parameter [age] to fn

def fn(*ages, age):
    pass

fn(age = 10) # <=== work
fn(123, 456, 789) # <=== error
fn(123, 456, age=789) # <=== work

• Keyword-only arguments without positional arguments
  • If you only accept keyword-only arguments, positional arguments are not allowed: using * without anything after it

def fn(*, name, age):
    pass

fn(name="Tim", age=20) # <=== work

• Ex