103 lines
2.8 KiB
Markdown
103 lines
2.8 KiB
Markdown
|
# Chapter 8. Functions
|
||
|
|
|
||
|
|
## Passing an Arbitrary Number of Arguments
|
||
|
|
|
||
|
|
* Function uses `*arg_name` to collects arbitrary number of arguments.
|
||
|
|
* `*` in parameter tells Python to make an empty tuple called `arg_name` and pack whatever values it receives into this tuple
|
||
|
|
|
||
|
|
NOTE: `*args` is open used as **generic parameter** name
|
||
|
|
|
||
|
|
```python
|
||
|
|
def make_pizza(*toppings):
|
||
|
|
"""Summarize the pizza we are about to make."""
|
||
|
|
print("\nMaking a pizza with the following toppings:")
|
||
|
|
for topping in toppings:
|
||
|
|
print(f"- {topping}")
|
||
|
|
|
||
|
|
make_pizza('pepperoni')
|
||
|
|
make_pizza('mushrooms', 'green peppers', 'extra cheese')
|
||
|
|
```
|
||
|
|
|
||
|
|
## Mixing Positional and Arbitrary Arguments
|
||
|
|
|
||
|
|
* If function accept different kinds of arguments, Arbitrary Arguments must be placed at last.
|
||
|
|
|
||
|
|
```python
|
||
|
|
def make_pizza(size, *toppings):
|
||
|
|
"""Summarize the pizza we are about to make."""
|
||
|
|
print(f"\nMaking a {size}-inch pizza with the following toppings:")
|
||
|
|
for topping in toppings:
|
||
|
|
print(f"- {topping}")
|
||
|
|
|
||
|
|
make_pizza(16, 'pepperoni')
|
||
|
|
make_pizza(12, 'mushrooms', 'green peppers', 'extra cheese')
|
||
|
|
```
|
||
|
|
|
||
|
|
## Using Arbitrary Keyword Arguments
|
||
|
|
|
||
|
|
* Function can use double asterisks `**` to cause Python to create an empty dictionary called **user_info** and pack whatever name-value pairs.
|
||
|
|
|
||
|
|
```python
|
||
|
|
def build_profile(first, last, **user_info):
|
||
|
|
"""Build a dictionary containing everything we know about a user."""
|
||
|
|
user_info['first_name'] = first
|
||
|
|
user_info['last_name'] = last
|
||
|
|
return user_info
|
||
|
|
|
||
|
|
|
||
|
|
user_profile = build_profile('albert', 'einstein',
|
||
|
|
location='princeton',
|
||
|
|
field='physics')
|
||
|
|
print(user_profile)
|
||
|
|
|
||
|
|
{'location': 'princeton', 'field': 'physics',
|
||
|
|
'first_name': 'albert', 'last_name': 'einstein'}
|
||
|
|
```
|
||
|
|
|
||
|
|
## Storing Your Functions in Modules
|
||
|
|
|
||
|
|
Functions can be stored in different modules (python scripts) for better management.
|
||
|
|
|
||
|
|
### Importing an Entire Module
|
||
|
|
|
||
|
|
```python
|
||
|
|
import pizza
|
||
|
|
|
||
|
|
pizza.make_pizza(16, 'pepperoni')
|
||
|
|
pizza.make_pizza(12, 'mushrooms', 'green peppers', 'extra cheese')
|
||
|
|
```
|
||
|
|
|
||
|
|
### Importing Specific Functions
|
||
|
|
|
||
|
|
```python
|
||
|
|
from module_name import function_name
|
||
|
|
```
|
||
|
|
|
||
|
|
### Using as to Give a Function an Alias
|
||
|
|
|
||
|
|
```python
|
||
|
|
from module_name import function_name as fn
|
||
|
|
```
|
||
|
|
|
||
|
|
### Using as to Give a Module an Alias
|
||
|
|
|
||
|
|
```python
|
||
|
|
import pizza as p
|
||
|
|
|
||
|
|
p.make_pizza(16, 'pepperoni')
|
||
|
|
p.make_pizza(12, 'mushrooms', 'green peppers', 'extra cheese')
|
||
|
|
```
|
||
|
|
|
||
|
|
### Importing All Functions in a Module
|
||
|
|
|
||
|
|
```python
|
||
|
|
from module_name import *
|
||
|
|
```
|
||
|
|
|
||
|
|
## Styling Functions
|
||
|
|
|
||
|
|
* Functions should have descriptive names, and function names should be lowercase letters and underscores.
|
||
|
|
* Every function should have a comment that explain concisely what the function does.
|
||
|
|
* If specify a default value, no space separation `def function_name(parameter_0, parameter_1='default value')`
|
||
|
|
|
||
|
|
Generally follow PEP8
|