@litert/decorator 库是一个 TypeScript 的装饰器工具包，提供了大量的工具方法用以提高装饰器的开发效率。
关于装饰器的使用，可阅读 《官方文档：装饰器》 和 《TypeScript装饰器完全指南》。
目前 TypeScript 支持如下类型的装饰器：
- 类装饰器
- 类构造函数参数装饰器
- 类成员属性装饰
- 类成员方法装饰
- 类成员方法参数装饰器
- 类成员访问器装饰器
- 类静态属性装饰
- 类静态方法装饰
- 类静态方法参数装饰器
- 类静态访问器装饰器
npm i @litert/decorator -Simport $Decorators from '@litert/decorator';通过 TypeScript 的 default 引入的 $Decorators 是一个 IDecoratorUtility 类型的对象，提供各种工具方法。
import $Decorators, { IClassDecorator } from '@litert/decorator';
const classDecorator: IClassDecorator = function(clsCtor): void {
if (!$Decorators.isInsideClassDecorator([clsCtor])) {
throw new TypeError('Invalid parameters for class decorator.');
}
console.log(`Decorated class ${clsCtor.name}`);
};
@classDecorator
class Test {}使用工具方法时，会自动检测传递给装饰器的参数是否正确，以免将装饰器用在错误的位置，或者错误的调用装饰器函数。（下同）
import $Decorators from '@litert/decorator';
const classDecorator = $Decorators.createClassDecorator(function(clsCtor): void {
console.log(`Decorated class ${clsCtor.name}`);
});
@classDecorator
class Test {}查看示例代码。
import $Decorators, { IMethodDecorator } from '@litert/decorator';
const methodDecorator: IMethodDecorator = function(clsProto, methodName, dtr): void {
if (!$Decorators.isInsideMethodDecorator([clsProto, methodName, dtr])) {
throw new TypeError('Invalid parameters for method decorator.');
}
console.log(`Decorated method ${clsProto.constructor.name}::${methodName}`);
};
class Test {
@methodDecorator
public method(): void {}
}import $Decorators from '@litert/decorator';
const methodDecorator = $Decorators.createMethodDecorator(function(clsProto, methodName): void {
console.log(`Decorated method ${clsProto.constructor.name}::${methodName}`);
});
class Test {
@methodDecorator
public method(): void {}
}查看示例代码。
import $Decorators, { IPropertyDecorator } from '@litert/decorator';
const propertyDecorator: IPropertyDecorator = function(clsProto, propName): void {
if (!$Decorators.isInsidePropertyDecorator([clsProto, propName])) {
throw new TypeError('Invalid parameters for property decorator.');
}
console.log(`Decorated property ${clsProto.constructor.name}::${propName}`);
};
class Test {
@propertyDecorator
public value = 321;
}import $Decorators from '@litert/decorator';
const propertyDecorator = $Decorators.createPropertyDecorator(function(clsProto, propName): void {
console.log(`Decorated property ${clsProto.constructor.name}::${propName}`);
});
class Test {
@propertyDecorator
public value = 321;
}查看示例代码。
import $Decorators, { IStaticMethodDecorator } from '@litert/decorator';
const staticMethodDecorator: IStaticMethodDecorator = function(clsCtor, methodName, dtr): void {
if (!$Decorators.isInsideStaticMethodDecorator([clsCtor, methodName, dtr])) {
throw new TypeError('Invalid parameters for static method decorator.');
}
console.log(`Decorated static method ${clsCtor.name}::${methodName}`);
};
class Test {
@staticMethodDecorator
public static method(): void {}
}import $Decorators from '@litert/decorator';
const staticMethodDecorator = $Decorators.createStaticMethodDecorator(function(clsCtor, methodName): void {
console.log(`Decorated static method ${clsCtor.name}::${methodName}`);
});
class Test {
@staticMethodDecorator
public static method(): void {}
}查看示例代码。
import $Decorators, { IStaticPropertyDecorator } from '@litert/decorator';
const staticPropertyDecorator: IStaticPropertyDecorator = function(clsCtor, propName): void {
if (!$Decorators.isInsideStaticPropertyDecorator([clsCtor, propName])) {
throw new TypeError('Invalid parameters for static property decorator.');
}
console.log(`Decorated static property ${clsCtor.name}::${propName}`);
};
class Test {
@staticPropertyDecorator
public static value = 321;
}import $Decorators from '@litert/decorator';
const staticPropertyDecorator = $Decorators.createStaticPropertyDecorator(function(clsCtor, propName): void {
console.log(`Decorated static property ${clsCtor.name}::${propName}`);
});
class Test {
@staticPropertyDecorator
public static value = 321;
}查看示例代码。
import $Decorators, { IMethodParameterDecorator } from '@litert/decorator';
const methodParamDecorator: IMethodParameterDecorator = function(clsProto, methodName, index): void {
if (!$Decorators.isInsideMethodParameterDecorator([clsProto, methodName, index])) {
throw new TypeError('Invalid parameters for method parameter decorator.');
}
console.log(`Decorated method parameter ${clsProto.constructor.name}::${methodName}[${index}]`);
};
class Test {
public method(@methodParamDecorator v: number): void {}
}import $Decorators from '@litert/decorator';
const methodParamDecorator = $Decorators.createMethodParameterDecorator(function(clsProto, methodName, index): void {
console.log(`Decorated method parameter ${clsProto.constructor.name}::${methodName}[${index}]`);
});
class Test {
public method(@methodParamDecorator v: number): void {}
}查看示例代码。
注意：由于 TypeScript 的实现问题，导致静态的参数装饰器（在编译时）可以接受非静态的参数装饰器，但是运行时无法通过参数检查。
import $Decorators, { IStaticMethodParameterDecorator } from '@litert/decorator';
const methodParamDecorator: IStaticMethodParameterDecorator = function(clsCtor, methodName, index): void {
if (!$Decorators.isInsideStaticMethodParameterDecorator([clsCtor, methodName, index])) {
throw new TypeError('Invalid parameters for static method parameter decorator.');
}
console.log(`Decorated static method parameter ${clsCtor.name}::${methodName}[${index}]`);
};
class Test {
public static method(@methodParamDecorator v: number): void {}
}import $Decorators from '@litert/decorator';
const methodParamDecorator = $Decorators.createStaticMethodParameterDecorator(function(clsCtor, methodName, index): void {
console.log(`Decorated static method parameter ${clsCtor.name}::${methodName}[${index}]`);
});
class Test {
public static method(@methodParamDecorator v: number): void {}
}查看示例代码。
import $Decorators, { IConstructorParameterDecorator } from '@litert/decorator';
const ctorParamDecorator: IConstructorParameterDecorator = function(clsCtor, methodName, index): void {
if (!$Decorators.isInsideConstructorParameterDecorator([clsCtor, methodName, index])) {
throw new TypeError('Invalid parameters for constructor parameter decorator.');
}
console.log(`Decorated constructor parameter ${clsCtor.name}::constructor[${index}]`);
};
class Test {
public constructor(@ctorParamDecorator v: number) {}
}import $Decorators from '@litert/decorator';
const ctorParamDecorator = $Decorators.createConstructorParameterDecorator(function(clsCtor, methodName, index): void {
console.log(`Decorated constructor parameter ${clsCtor.name}::constructor[${index}]`);
});
class Test {
public constructor(@ctorParamDecorator v: number) {}
}查看示例代码。
访问器装饰器是指对 getter/setter 的装饰器。
需要注意的是，虽然 TypeScript 在语法上允许 Setter 参数装饰器，但实际上不会生效。 因此并不存在 Setter 参数装饰器 和 静态 Setter 参数装饰器。
此外，访问器装饰器的函数签名与方法装饰器一致，因此千万注意切莫用错了地方。
import $Decorators, { IMethodDecorator } from '@litert/decorator';
const accessorDecorator: IMethodDecorator = function(clsProto, accessorName, dtr): void {
if (!$Decorators.isInsideAccessorDecorator([clsProto, accessorName, dtr])) {
throw new TypeError('Invalid parameters for accessor decorator.');
}
console.log(`Decorated accessor ${clsProto.constructor.name}::${accessorName}`);
};
class Test {
@accessorDecorator
public get value(): number { return 123; }
@accessorDecorator
public set price(v: number) { /* do something */ }
}import $Decorators from '@litert/decorator';
const accessorDecorator = $Decorators.createAccessorDecorator(function(clsProto, accessorName): void {
console.log(`Decorated accessor ${clsProto.constructor.name}::${accessorName}`);
});
class Test {
@accessorDecorator
public get value(): number { return 123; }
@accessorDecorator
public set price(v: number) { /* do something */ }
}查看示例代码。
import $Decorators, { IStaticMethodDecorator } from '@litert/decorator';
const accessorDecorator: IStaticMethodDecorator = function(clsCtor, accessorName, dtr): void {
if (!$Decorators.isInsideStaticAccessorDecorator([clsCtor, accessorName, dtr])) {
throw new TypeError('Invalid parameters for static accessor decorator.');
}
console.log(`Decorated static accessor ${clsCtor.name}::${accessorName}`);
};
class Test {
@accessorDecorator
public static get value(): number { return 123; }
@accessorDecorator
public static set price(v: number) { /* do something */ }
}import $Decorators from '@litert/decorator';
const accessorDecorator = $Decorators.createStaticAccessorDecorator(function(clsCtor, accessorName): void {
console.log(`Decorated static accessor ${clsCtor.name}::${accessorName}`);
});
class Test {
@accessorDecorator
public static get value(): number { return 123; }
@accessorDecorator
public static set price(v: number) { /* do something */ }
}查看示例代码。
通用装饰器是指一个装饰器可以（在语法上）适配所有可装饰点，这种装饰器需要在装饰器内进行装饰点的判断。
import $Decorators, { IGeneralDecorator } from '@litert/decorator';
const theDecorator: IGeneralDecorator = function(clsCtor, methodName, index): void {
if ($Decorators.isInsideConstructorParameterDecorator([clsCtor, methodName, index])) {
console.log(`Decorated constructor parameter ${clsCtor.name}::constructor[${index}]`);
}
else if ($Decorators.isInsideMethodParameterDecorator([clsProto, methodName, index])) {
console.log(`Decorated member method parameter ${clsProto.constructor.name}::constructor[${index}]`);
}
else {
// 其它装饰情况。
}
};
class Test {
public constructor(@theDecorator v: number) {}
public static staticMethod(@theDecorator v: number): void {}
}import $Decorators from '@litert/decorator';
const theDecorator = $Decorators.createGeneralDecorator({
'ctorParameter': function(clsCtor, methodName, index): void {
console.log(`Decorated constructor parameter ${clsCtor.name}::constructor[${index}]`);
},
'staticMethodParameter': function(clsCtor, methodName, index): void {
console.log(`Decorated static method parameter ${clsCtor.name}::${methodName}[${index}]`);
}
});
class Test {
public constructor(@theDecorator v: number) {}
public static staticMethod(@theDecorator v: number): void {}
}查看示例代码。