内置类型¶
本章介绍一些常用的内置类型。 稍后我们将介绍许多其他类型。
Built-in types
This chapter introduces some commonly used built-in types. We will cover many other kinds of types later.
简单类型¶
以下是一些常见内置类型的示例：
| 类型 | 描述 |
|---|---|
int |
整数 |
float |
浮点数 |
bool |
布尔值（int的子类） |
str |
文本，unicode 代码点序列 |
bytes |
8 位字符串，字节值序列 |
object |
任意对象（object是公共基类） |
所有内置类都可以用作类型。
Simple types
Here are examples of some common built-in types:
| Type | Description |
|---|---|
int |
integer |
float |
floating point number |
bool |
boolean value (subclass of int) |
str |
text, sequence of unicode codepoints |
bytes |
8-bit string, sequence of byte values |
object |
an arbitrary object (object is the common base class) |
All built-in classes can be used as types.
| Type | Description |
|---|---|
| aaa | bbb |
| aaa | bbb |
| aaa | bbb |
| aaa | bbb |
| aaa | bbb |
Any type¶
如果你找不到某个值的合适类型，你可以随时回退到 Any：
| Type | Description |
|---|---|
Any |
任意类型的动态类型值 |
Any type
If you can’t find a good type for some value, you can always fall back to Any:
| Type | Description |
|---|---|
Any |
dynamically typed value with an arbitrary type |
The type Any is defined in the typing module. See Dynamically typed code for more details.
范型类型¶
在Python 3.9及更高版本中，内置集合类型对象支持索引：
| 类型 | 描述 |
|---|---|
list[str] |
str 对象列表 |
tuple[int, int] |
两个 int 对象的元组（tuple[()] 是空元组） |
tuple[int, ...] |
任意数量的 int 对象的元组 |
dict[str, int] |
字典从 str 键到 int 值 |
Iterable[int] |
包含整数的可迭代对象 |
Sequence[bool] |
布尔值序列（只读） |
Mapping[str, int] |
从 str 键到 int 值的映射（只读） |
type[C] |
C 的类型对象（C 是类/类型变量/类型联合） |
类型 dict 是一个泛型类，由 [...] 中的类型参数表示。 例如，dict[int, str] 是从整数到字符串的字典，dict[Any, Any] 是动态类型（任意）值和键的字典。 list 是另一个泛型类。
Iterable、Sequence 和 Mapping 是与 Python 协议相对应的泛型类型。 例如，当需要Iterable[str]或Sequence[str]时，str对象或list[str]对象是有效的。 您可以从 collections.abc 导入，而不是从 Python 3.9 中的 typing导入它们。
有关更多详细信息，请参阅 generic-builtins，包括如何在 Python 3.7 和 3.8 中的注释中使用它们。
如果您需要支持 Python 3.8 及更早版本，则需要 typing 中定义的这些旧类型：
| 类型 | 描述 |
|---|---|
List[str] |
str 对象列表 |
Tuple[int, int] |
两个 int 对象的元组（tuple[()] 是空元组） |
Tuple[int, ...] |
任意数量的 int 对象的元组 |
Dict[str, int] |
字典从 str 键到 int 值 |
Iterable[int] |
包含整数的可迭代对象 |
Sequence[bool] |
布尔值序列（只读） |
Mapping[str, int] |
从 str 键到 int 值的映射（只读） |
Type[C] |
C 的类型对象（C 是类/类型变量/类型联合） |
List 是支持索引的内置类型 list 的别名 (dict/Dict 和 tuple/Tuple 也都是类似的).
请注意，尽管 Iterable、Sequence 和 Mapping 看起来与 collections.abc（以前的 collections）中定义的抽象基类类似，但它们并不相同，因为后者不支持索引 Python 3.9 之前的版本。
Generic types
In Python 3.9 and later, built-in collection type objects support indexing:
| Type | Description |
|---|---|
list[str] |
list of str objects |
tuple[int, int] |
tuple of two int objects (tuple[()] is the empty tuple) |
tuple[int, ...] |
tuple of an arbitrary number of int objects |
dict[str, int] |
dictionary from str keys to int values |
Iterable[int] |
iterable object containing ints |
Sequence[bool] |
sequence of booleans (read-only) |
Mapping[str, int] |
mapping from str keys to int values (read-only) |
type[C] |
type object of C (C is a class/type variable/union of types) |
The type dict is a generic class, signified by type arguments within [...]. For example, dict[int, str] is a dictionary from integers to strings and dict[Any, Any] is a dictionary of dynamically typed (arbitrary) values and keys. list is another generic class.
Iterable, Sequence, and Mapping are generic types that correspond to Python protocols. For example, a str object or a list[str] object is valid when Iterable[str] or Sequence[str] is expected. You can import them from collections.abc instead of importing from typing in Python 3.9.
See generic-builtins for more details, including how you can use these in annotations also in Python 3.7 and 3.8.
These legacy types defined in typing are needed if you need to support Python 3.8 and earlier:
| Type | Description |
|---|---|
List[str] |
list of str objects |
Tuple[int, int] |
tuple of two int objects (Tuple[()] is the empty tuple) |
Tuple[int, ...] |
tuple of an arbitrary number of int objects |
Dict[str, int] |
dictionary from str keys to int values |
Iterable[int] |
iterable object containing ints |
Sequence[bool] |
sequence of booleans (read-only) |
Mapping[str, int] |
mapping from str keys to int values (read-only) |
Type[C] |
type object of C (C is a class/type variable/union of types) |
List is an alias for the built-in type list that supports indexing (and similarly for dict/Dict and tuple/Tuple).
Note that even though Iterable, Sequence and Mapping look similar to abstract base classes defined in collections.abc (formerly collections), they are not identical, since the latter don't support indexing prior to Python 3.9.