Python 函数

1. 函数

def describe_pet(animal_type, pet_name):
    print("\nI have a " + animal_type + ".")
    print("My " + animal_type + "'s name is " + pet_name.title() + ".")


describe_pet('hamster', 'harry')
describe_pet('dog', 'willie')

2. 关键字实参

def describe_pet(animal_type, pet_name):
    print("\nI have a " + animal_type + ".")
    print("My " + animal_type + "'s name is " + pet_name.title() + ".")


describe_pet(pet_name='harry', animal_type='hamster')

3. 默认值

def describe_pet(pet_name, animal_type="dog"):
    print("\nI have a " + animal_type + ".")
    print("My " + animal_type + "'s name is " + pet_name.title() + ".")


describe_pet(animal_type='hamster', pet_name='harry')
describe_pet(pet_name='jim')

实例输出：

默认值

4. 返回简单值

def get_formatted_name(first_name, last_name):
    full_name = first_name + ' ' + last_name
    return full_name.title()


musician = get_formatted_name('jim', 'hendrix')
print(musician)

5. 让实参变成可选的

def get_formatted_name(first_name, last_name, middle_name=""):
    if middle_name:
        full_name = first_name + ' ' + middle_name + ' ' + last_name
    else:
        full_name = first_name + ' ' + last_name
    return full_name.title()


musician = get_formatted_name('john', 'hooker')
print(musician)

musician = get_formatted_name('john', 'hooker', "lee")
print(musician)

6. 传递列表

def greet_users(names):
    for name in names:
        print("Hello, " + name.title() + "!")


user_names = ["toby", "tina", "john"]
greet_users(user_names)

7. 在函数中修改列表

def print_models(designs, models):
    while designs:
        current_design = designs.pop()
        print("Printing model: " + current_design)
        models.append(current_design)


def show_completed_models(models):
    print("\nThe following models have been printed:")
    for completed_model in models:
        print(completed_model)


unprinted_designs = ['iphone case', 'robot pendant', 'dodecahedron']
completed_models = []

print_models(unprinted_designs, completed_models)
show_completed_models(completed_models)

8. 禁止函数修改列表

def print_models(designs, models):
    while designs:
        current_design = designs.pop()
        print("Printing model: " + current_design)
        models.append(current_design)


def show_models(models):
    print("\nThe following models have been printed:")
    for completed_model in models:
        print(completed_model)


unprinted_designs = ['iphone case', 'robot pendant', 'dodecahedron']
completed_models = []

print_models(unprinted_designs[:], completed_models)  # 使用切片将副本传入
show_models(completed_models)
print(unprinted_designs)

9. 传递任意数量的实参

def make_pizza(*toppings):
    print("\nMaking a pizza with the following toppings:")
    for topping in toppings:
        print("- " + topping)


make_pizza('pepperoni')
make_pizza('mushrooms', 'green peppers', 'extra cheese')

10. 结合使用位置实参和任意数量实参

def make_pizza(size, *toppings):
    print("\nMaking a " + str(size) + "-inch pizza with the following toppings:")
    for topping in toppings:
        print("- " + topping)


make_pizza(16, 'pepperoni')
make_pizza(12, 'mushrooms', 'green peppers', 'extra cheese')

11. 使用任意数量的关键字实参

def build_profile(first, last, **user_info):
    profile = {"first_name": first, "last_name": last}
    for key, value in user_info.items():
        profile[key] = value
    return profile


user_profile = build_profile('albert', 'einstein',
                             location='princeton',
                             field='physics')
print("User Profile:")
print(user_profile)

输出结果：

使用任意数量的关键字实参

12. 导入整个模块

定义 pizza.py 文件：

pizza.py 文件

使用整个模块：

使用整个模块

13. 导入特定的函数

from pizza import make_pizza

make_pizza(16, 'pepperoni')
make_pizza(12, 'mushrooms', 'green peppers', 'extra cheese')

14. 使用 as 给函数指定别名

from pizza import make_pizza as mp

mp(16, 'pepperoni')
mp(12, 'mushrooms', 'green peppers', 'extra cheese')

15. 使用 as 给模块指定别名

import pizza as mp

mp.make_pizza(16, 'pepperoni')
mp.make_pizza(12, 'mushrooms', 'green peppers', 'extra cheese')

16. 导入模块中的所有函数

from pizza import *

make_pizza(16, 'pepperoni')
make_pizza(12, 'mushrooms', 'green peppers', 'extra cheese')

本文参考自 《Python 编程：从入门到实践》