Python 对象和类指令
Gaia 框架为 Python 后端提供了完整的面向对象编程指令集，支持类定义、继承、多态、数据类、抽象类等高级特性。
类和对象基础
基本类定义
python
# Gaia 代码
class Person:
def __init__(self, name: str, age: int):
self.name = name
self.age = age
def greet(self) -> str:
return f"Hello, I'm {self.name}"
def get_age(self) -> int:
return self.age对象创建和使用
python
# Gaia 代码
CREATE_OBJECT person Person "Alice" 25
call_method person "greet" greeting
call_method person "get_age" age编译为 Python 代码：
python
# 生成的 Python 代码
person = Person("Alice", 25)
greeting = person.greet()
age = person.get_age()继承和多态
单继承
python
# Gaia 代码
class Employee(Person):
def __init__(self, name: str, age: int, employee_id: str):
super().__init__(name, age)
self.employee_id = employee_id
def greet(self) -> str:
return f"Hello, I'm {self.name}, employee {self.employee_id}"
def work(self) -> str:
return f"{self.name} is working"多继承
python
# Gaia 代码
class Manager(Employee, Leader):
def __init__(self, name: str, age: int, employee_id: str, department: str):
Employee.__init__(self, name, age, employee_id)
Leader.__init__(self, department)
def manage(self) -> str:
return f"{self.name} is managing {self.department}"方法重写
python
# Gaia 代码
class Student(Person):
def __init__(self, name: str, age: int, student_id: str):
super().__init__(name, age)
self.student_id = student_id
def greet(self) -> str:
return f"Hi, I'm {self.name}, student ID: {self.student_id}"特殊方法和运算符重载
字符串表示
python
# Gaia 代码
class Book:
def __init__(self, title: str, author: str, pages: int):
self.title = title
self.author = author
self.pages = pages
def __str__(self) -> str:
return f"{self.title} by {self.author}"
def __repr__(self) -> str:
return f"Book('{self.title}', '{self.author}', {self.pages})"运算符重载
python
# Gaia 代码
class Vector:
def __init__(self, x: float, y: float):
self.x = x
self.y = y
def __add__(self, other: 'Vector') -> 'Vector':
return Vector(self.x + other.x, self.y + other.y)
def __mul__(self, scalar: float) -> 'Vector':
return Vector(self.x * scalar, self.y * scalar)
def __len__(self) -> int:
return 2
def __getitem__(self, index: int) -> float:
if index == 0:
return self.x
elif index == 1:
return self.y
raise IndexError("Vector index out of range")比较运算符
python
# Gaia 代码
class Product:
def __init__(self, name: str, price: float):
self.name = name
self.price = price
def __eq__(self, other: object) -> bool:
if not isinstance(other, Product):
return False
return self.name == other.name and self.price == other.price
def __lt__(self, other: 'Product') -> bool:
return self.price < other.price
def __hash__(self) -> int:
return hash((self.name, self.price))属性管理
属性装饰器
python
# Gaia 代码
class Circle:
def __init__(self, radius: float):
self._radius = radius
@property
def radius(self) -> float:
return self._radius
@radius.setter
def radius(self, value: float):
if value < 0:
raise ValueError("Radius cannot be negative")
self._radius = value
@property
def area(self) -> float:
return 3.14159 * self._radius ** 2
@property
def circumference(self) -> float:
return 2 * 3.14159 * self._radius属性描述符
python
# Gaia 代码
class TemperatureDescriptor:
def __init__(self):
self._value = 0
def __get__(self, obj, objtype=None):
return self._value
def __set__(self, obj, value):
if value < -273.15:
raise ValueError("Temperature cannot be below absolute zero")
self._value = value
class Thermometer:
celsius = TemperatureDescriptor()数据类
基本数据类
python
# Gaia 代码
from dataclasses import dataclass
@dataclass
class Point:
x: float
y: float
def distance_to(self, other: 'Point') -> float:
return ((self.x - other.x) ** 2 + (self.y - other.y) ** 2) ** 0.5高级数据类
python
# Gaia 代码
@dataclass(frozen=True)
class ImmutablePoint:
x: float
y: float
@dataclass
class Config:
host: str = "localhost"
port: int = 8080
debug: bool = False
def __post_init__(self):
if self.port < 1024:
raise ValueError("Port must be >= 1024")抽象类和接口
抽象基类
python
# Gaia 代码
from abc import ABC, abstractmethod
class Shape(ABC):
@abstractmethod
def area(self) -> float:
pass
@abstractmethod
def perimeter(self) -> float:
pass
def describe(self) -> str:
return f"Shape with area {self.area()} and perimeter {self.perimeter()}"
class Rectangle(Shape):
def __init__(self, width: float, height: float):
self.width = width
self.height = height
def area(self) -> float:
return self.width * self.height
def perimeter(self) -> float:
return 2 * (self.width + self.height)接口协议
python
# Gaia 代码
from typing import Protocol
class Drawable(Protocol):
def draw(self) -> str:
...
class Circle:
def __init__(self, radius: float):
self.radius = radius
def draw(self) -> str:
return f"Drawing circle with radius {self.radius}"元类和动态类创建
元类
python
# Gaia 代码
class SingletonMeta(type):
_instances = {}
def __call__(cls, *args, **kwargs):
if cls not in cls._instances:
cls._instances[cls] = super().__call__(*args, **kwargs)
return cls._instances[cls]
class Database(metaclass=SingletonMeta):
def __init__(self):
self.connection = "Connected"动态类创建
python
# Gaia 代码
def create_model_class(name: str, fields: dict) -> type:
return type(name, (), fields)
User = create_model_class("User", {
"__init__": lambda self, name: setattr(self, "name", name),
"__str__": lambda self: f"User({self.name})"
})对象序列化
Pickle 支持
python
# Gaia 代码
import pickle
class SerializableObject:
def __init__(self, data: any):
self.data = data
self.created_at = time.time()
def __getstate__(self):
state = self.__dict__.copy()
# 自定义序列化逻辑
return state
def __setstate__(self, state):
self.__dict__.update(state)
# 自定义反序列化逻辑JSON 序列化
python
# Gaia 代码
import json
class JSONMixin:
def to_json(self) -> str:
return json.dumps(self.__dict__)
@classmethod
def from_json(cls, json_str: str):
data = json.loads(json_str)
return cls(**data)内存管理
弱引用
python
# Gaia 代码
import weakref
class Cache:
def __init__(self):
self._cache = weakref.WeakValueDictionary()
def get(self, key: str):
return self._cache.get(key)
def set(self, key: str, value: object):
self._cache[key] = value对象池
python
# Gaia 代码
class ObjectPool:
def __init__(self, factory_func, max_size: int = 100):
self.factory_func = factory_func
self.pool = []
self.max_size = max_size
def acquire(self):
if self.pool:
return self.pool.pop()
return self.factory_func()
def release(self, obj):
if len(self.pool) < self.max_size:
self.pool.append(obj)性能优化
类属性缓存
python
# Gaia 代码
class CachedProperty:
def __init__(self, func):
self.func = func
self.name = func.__name__
def __get__(self, obj, objtype=None):
if obj is None:
return self
value = self.func(obj)
setattr(obj, self.name, value)
return value
class ExpensiveCalculation:
@CachedProperty
def expensive_result(self):
# 昂贵的计算
return sum(i**2 for i in range(1000000))对象复用
python
# Gaia 代码
class Flyweight:
_instances = {}
def __new__(cls, *args):
key = args
if key not in cls._instances:
cls._instances[key] = super().__new__(cls)
return cls._instances[key]最佳实践
- 封装性: 使用私有属性和方法保护内部实现
- 继承层次: 保持继承层次简单，优先考虑组合
- 类型注解: 为类属性和方法参数添加类型注解
- 文档字符串: 为类和方法编写清晰的文档
- 异常处理: 在构造函数和方法中适当处理异常
- 资源管理: 使用上下文管理器管理资源
- 性能考虑: 避免在热路径中频繁创建对象