Python

Basic

Introduction 介绍

Python is a dynamic and strongly typed programming language. It employs both duck typing and gradual typing via type hints.

While Python supports many different programming styles, internally everything in Python is an object. This includes numbers, strings, lists, and even functions.

Python是一个动态和强类型编程语言；

Name Assignment(Variables & Constants) 命名规范

Constant 常量

Constants are names meant to be assigned only once in a program. They should be defined at a module (file) level, and are typically visible to all functions and classes in the program. Using SCREAMING_SNAKE_CASE signals that the name should not be re-assigned, or its value mutated.

常量需要能够被明显辨认出；

Comment 注释

Comments in Python start with a # that is not part of a string, and end at line termination. Unlike many other programming languages, Python does not support multi-line comment marks. Each line of a comment block must start with the # character.

1. 注释使用一个#

2. 只能注释单行

Docstrings 文档字符串（文档注释）

# An example from PEP257 of a multi-line docstring.
def complex(real=0.0, imag=0.0):
    """Form a complex number.

    Keyword arguments:
    real -- the real part (default 0.0)
    imag -- the imaginary part (default 0.0)
    """

    if imag == 0.0 and real == 0.0:
        return complex_zero

文档字符串使用三重双引号（"""）声明，并与代码块相同的缩进级别。

Docstrings are read by automated documentation tools and are returned by calling the special attribute .__doc__ on the function, method, or class name. Docstring conventions are laid out in PEP257.

Docstrings can also function as lightweight unit tests, which will be covered in a later exercise.

# An example on a user-defined function.
>>> def number_to_the_power_of(number_one, number_two):
        """Raise a number to an arbitrary power.

        :param number_one: int the base number.
        :param number_two: int the power to raise the base number to.
        :return: int - number raised to power of second number

        Takes number_one and raises it to the power of number_two, returning the result.
        """

        return number_one ** number_two
...

# Calling the .__doc__ attribute of the function and printing the result.
>>> print(number_to_the_power_of.__doc__)
Raise a number to an arbitrary power.

    :param number_one: int the base number.
    :param number_two: int the power to raise the base number to.
    :return: int - number raised to power of second number

    Takes number_one and raises it to the power of number_two, returning the result.

文档字符串可以被调用，通过 方法名.__doc__