decorate

概述

decorate 函数是一个实用程序，允许你以编程方式将装饰器应用于类、方法、属性和构造函数参数，而无需使用装饰器语法 (@decorator)。这在以下情况下特别有用：

1. 你无法修改原始类以添加装饰器
2. 你正在使用第三方类
3. 你想有条件地应用装饰器
4. 你处于装饰器语法不可用的环境中

API 参考

decorate 函数有多个重载来处理不同的装饰器类型：

function decorate(
  decorators: ClassDecorator | ClassDecorator[],
  target: Function
): void;

function decorate(
  decorators: ParameterDecorator | ParameterDecorator[],
  target: Function,
  parameterIndex: number
): void;

function decorate(
  decorators: MethodDecorator | PropertyDecorator | MethodDecorator[] | PropertyDecorator[],
  target: Function,
  property: string | symbol
): void;

export function decorate(
  decorators: ParameterDecorator | ParameterDecorator[],
  target: Function,
  methodName: string | symbol,
  parameterIndex: number,
): void;

示例

应用 ClassDecorator

使用此方法应用类级装饰器，如 @injectable()：

class Katana implements Weapon {
  public readonly damage: number = 10;
}

// Apply @injectable decorator using decorate function
decorate(injectable(), Katana);

const container: Container = new Container();
container.bind<Weapon>('Weapon').to(Katana);

const katana: Weapon = container.get<Weapon>('Weapon');

应用 ParameterDecorator

使用此方法将装饰器应用于构造函数参数，如 @inject()：

@injectable()
class Warrior {
  private readonly weapon: Weapon;

  constructor(weapon: Weapon) {
    this.weapon = weapon;
  }

  public fight(): string {
    return `Fighting with weapon damage: ${this.weapon.damage.toString()}`;
  }
}

// Apply @inject decorator to constructor parameter using decorate function
decorate(inject('Weapon'), Warrior, 0);

const container: Container = new Container();
container.bind<Weapon>('Weapon').to(Katana);
container.bind<Warrior>('Warrior').to(Warrior);

const warrior: Warrior = container.get<Warrior>('Warrior');

应用 PropertyDecorator

使用此方法将装饰器应用于类属性，如 @inject()：

@injectable()
class Warrior {
  public weapon!: Weapon;

  public fight(): string {
    return `Fighting with weapon damage: ${this.weapon.damage.toString()}`;
  }
}

// Apply @inject decorator to property using decorate function
decorate(inject('Weapon'), Warrior, 'weapon');

const container: Container = new Container();
container.bind<Weapon>('Weapon').to(Katana);
container.bind<Warrior>('Warrior').to(Warrior);

const warrior: Warrior = container.get<Warrior>('Warrior');

应用 MethodDecorator

使用此方法将装饰器应用于类方法：

@injectable()
class Katana implements Weapon {
  private _damage: number = 10;

  public get damage(): number {
    return this._damage;
  }

  public improve(): void {
    this._damage += 2;
  }
}

// Apply @postConstruct decorator to method using decorate function
decorate(postConstruct(), Katana, 'improve');

const container: Container = new Container();
container.bind<Weapon>('Weapon').to(Katana);

const katana: Katana = container.get<Weapon>('Weapon') as Katana;

用例

使用第三方类

当你需要使第三方类可注入但无法修改其源代码时：

import { decorate, injectable } from 'inversify';
import { SomeThirdPartyClass } from 'some-library';

// Make the third-party class injectable
decorate(injectable(), SomeThirdPartyClass);

条件装饰

根据运行时条件应用装饰器：

import { decorate, injectable } from 'inversify';

class MyService {
  // Implementation
}

// Conditionally make it injectable
if (process.env.NODE_ENV === 'production') {
  decorate(injectable(), MyService);
}

重要说明

• 必须在容器绑定中使用类之前调用 decorate 函数
• 对于 ParameterDecorator，参数索引是从 0 开始的（第一个参数 = 0，第二个 = 1，依此类推）
• 你可以传递单个装饰器或装饰器数组