我想这更像是一个好奇的问题,如果能够在打字稿中实际实现它会很好。
基本上我有一个类和两个方法就像这样:
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);
}
}
而不是这个?
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);
}
}
答案 0 :(得分:3)
您要实现的目标实际上并不是从其他方法签名中调用方法。它更多的是处理你的参数列表。
arguments
黑客您可以修改提供的arguments
数组,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
}
然而,这种做法很苛刻,你可以选择#2:
我们声明了两个装饰器: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);
}
一个名为CleanupMethod
的方法装饰器(它实际上是装饰工厂):
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,我们保存一个列表,列出哪些参数应该在函数输入时清理,然后在每次调用时清理它们。
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`
清理功能作为参数传递给CleanupMethod
工厂。这样你就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理功能移动到参数装饰器,但这会增加所需的代码量:
@CleanupMethod
insertString( @cleanup(cleanupString) str1: string, @cleanup(cleanupNumber) n1: number ){
/*...*/
}