javascript-Typescript：从方法参数中调用方法

我想这更多是一个好奇心问题,如果可以实际在打字稿中实现,那就太好了.

基本上,我有一个类和其中的两个方法,如下所示：

这可能吗？


class MyClass{
   private cleanup(str:String):String{
     //clean up the string
     return str; //return sanitized string
   }
   //I want to do this
   insertString(this.cleanup(text_1:String), this.cleanup(text_2:String)){
     console.log(text_1 + text_2);
   }
}

代替这个？


class MyClass{
   private cleanup(str:String):String{
     //clean up the string
     return str; //return sanitized string
   }
   //might get to long if I have to cleanup to many strings
   insertString(text_1:String, text_2:String){
     text_1 = this.cleanup(text_1)
     text_2 = this.cleanup(text_2)
     console.log(text_1 + text_2);
   }
}

解决方法:

您要实现的实际上不是从另一个方法签名中调用一个方法.更多有关处理参数列表的信息.

1：参数hack

您可以修改提供的arguments数组,并且相应的命名参数也会更改.

insertString(text_1:String, text_2:String) {
    // here text_1 and text_2 are not cleaned up yet
    for (var i = 0; i < arguments.length; i++) {
        arguments[i] = this.cleanup(arguments[i])
    }
    // text_1 and text_2 are Now cleaned up
}

但是,这种方法有点骇人听闻,您可以选择#2：

2：装饰器

我们声明两个装饰器：一个名为cleanup的参数装饰器：

function cleanup(target: Object, propertyKey: string | symbol, parameterIndex: number) {
    let cleanupParams: number[] = Reflect.getownMetadata("MyClass:cleanup", target, propertyKey) || [];
    cleanupParams.push(parameterIndex);
    Reflect.defineMetadata("MyClass:cleanup", cleanupParams, target, propertyKey);
}

还有一个名为CleanupMethod的方法修饰器(实际上是修饰器工厂)：

function CleanupMethod(func){
    return function (target: any, propertyName: string, descriptor: TypedPropertyDescriptor<Function>) {
        let method = descriptor.value;
        descriptor.value = function () {
            let requiredParameters: number[] = Reflect.getownMetadata("MyClass:cleanup", target, propertyName);
            if (requiredParameters) {
                for (let parameterIndex of requiredParameters) {
                    arguments[parameterIndex] = func(arguments[parameterIndex]);
                }
            }
            return method.apply(this, arguments);
        }
    }
}

在装饰器中,我们保存一个清单,其中应在函数enter中清除哪些参数,然后在每次调用时清除它们.

用法：

class MyClass{
    private cleanup(str:string):string{
        //clean up the string
        return '[sanitized ' + str + ']'; //return sanitized string
    }
    @CleanupMethod(MyClass.prototype.cleanup)
    insertString(text_1:string, @cleanup text_2:string){
        console.log(text_1 + text_2);
    }
    @CleanupMethod(MyClass.prototype.cleanup)
    insertNumber(n1: number, n2: number, @cleanup n3: number, n4: number, n5: number){
        console.log(`${n1} + ${n2} + ${n3} + ${n4} + ${n5}`)
    }
}
var m = new MyClass();
m.insertString('a', 'b') // outputs `a[sanitized b]`
m.insertNumber(10,20,30,40,50) // outputs `10 + 20 + [sanitized 30] + 40 + 50`

清除功能作为参数传递给CleanupMethod工厂.这样,您可以拥有不同的清理功能,例如：

@CleanupMethod(cleanupString)
insertString( @cleanup str1: string, @cleanup str2: string2 ){
    /*...*/
}
@CleanupMethod(cleanupNumber)
insertNumber( @cleanup n1: number ){
    /*...*/
}

如果需要,可以重写装饰器代码并将清除函数移至参数装饰器,但这将增加所需的代码量：

@CleanupMethod
insertString( @cleanup(cleanupString) str1: string, @cleanup(cleanupNumber) n1: number ){
    /*...*/
}

javascript-Typescript：从方法参数中调用方法

相关推荐