Data model - 数据模型

Data model
https://docs.python.org/3/reference/datamodel.html

数据模型
https://docs.python.org/zh-cn/3/reference/datamodel.html

1. numbers.Number

These are created by numeric literals and returned as results by arithmetic operators and arithmetic built-in functions. Numeric objects are immutable; once created their value never changes. Python numbers are of course strongly related to mathematical numbers, but subject to the limitations of numerical representation in computers.
此类对象由数字字面值创建，并会被作为算术运算符和算术内置函数的返回结果。数字对象是不可变的，一旦创建其值就不再改变。Python 中的数字当然非常类似数学中的数字，但也受限于计算机中的数字表示方法。

literal ['lɪt(ə)r(ə)l]：adj. 文字的，逐字的，无夸张的

Python distinguishes between integers, floating point numbers, and complex numbers:
Python 区分整型数、浮点型数和复数：

1.1 numbers.Integral

These represent elements from the mathematical set of integers (positive and negative).
此类对象表示数学中整数集合的成员 (包括正数和负数)。

There are two types of integers:
整型数可细分为两种类型：

1.1.1 Integers (int)

These represent numbers in an unlimited range, subject to available (virtual) memory only. For the purpose of shift and mask operations, a binary representation is assumed, and negative numbers are represented in a variant of 2’s complement which gives the illusion of an infinite string of sign bits extending to the left.
此类对象表示任意大小的数字，仅受限于可用的内存 (包括虚拟内存)。在变换和掩码运算中会以二进制表示，负数会以 2 的补码表示，看起来像是符号位向左延伸补满空位。

1.1.2 Booleans (bool)

These represent the truth values False and True. The two objects representing the values False and True are the only Boolean objects. The Boolean type is a subtype of the integer type, and Boolean values behave like the values 0 and 1, respectively, in almost all contexts, the exception being that when converted to a string, the strings “False” or “True” are returned, respectively.
此类对象表示逻辑值 False 和 True。代表 False 和 True 值的两个对象是唯二的布尔对象。布尔类型是整型的子类型，两个布尔值在各种场合的行为分别类似于数值 0 和 1，例外情况只有在转换为字符串时分别返回字符串 False 或 True。

The rules for integer representation are intended to give the most meaningful interpretation of shift and mask operations involving negative integers.
整型数表示规则的目的是在涉及负整型数的变换和掩码运算时提供最为合理的解释。

1.2 numbers.Real (float)

These represent machine-level double precision floating point numbers. You are at the mercy of the underlying machine architecture (and C or Java implementation) for the accepted range and handling of overflow. Python does not support single-precision floating point numbers; the savings in processor and memory usage that are usually the reason for using these are dwarfed by the overhead of using objects in Python, so there is no reason to complicate the language with two kinds of floating point numbers.
此类对象表示机器级的双精度浮点数。其所接受的取值范围和溢出处理将受制于底层的机器架构 (以及 C 或 Java 实现)。Python 不支持单精度浮点数；支持后者通常的理由是节省处理器和内存消耗，但这点节省相对于在 Python 中使用对象的开销来说太过微不足道，因此没有理由包含两种浮点数而令该语言变得复杂。

1.3 numbers.Complex (complex)

These represent complex numbers as a pair of machine-level double precision floating point numbers. The same caveats apply as for floating point numbers. The real and imaginary parts of a complex number z can be retrieved through the read-only attributes z.real and z.imag.
此类对象以一对机器级的双精度浮点数来表示复数值。有关浮点数的附带规则对其同样有效。一个复数值 z 的实部和虚部可通过只读属性 z.real 和 z.imag 来获取。

mercy ['mɜːsɪ]：n. 仁慈，宽容，怜悯，幸运，善行

2. Numeric Types - int, float, complex

There are three distinct numeric types: integers, floating point numbers, and complex numbers.
有三种不同的数字类型：整数、浮点数和复数。

Python 的数字类型包括 Integral (int、bool)、Real (float) 和 Complex (complex) 类型。