有没有Scala功能允许您调用名称存储在字符串中的方法? [英] Is there any Scala feature that allows you to call a method whose name is stored in a string?
问题描述
类似Ruby的发送
参数。
您可以在Java中进行反思:
class A {
def cat(s1:String,s2:String)= s1 ++ s2
}
val a = new A
val hi =Hello
val all =世界
val方法= a.getClass.getMethod(cat,hi.getClass,all.getClass)
method.invoke(a,hi,all)
如果您希望在Scala中轻松实现,您可以为您做一个类,另外还有一个隐含的转换:
案例类调用者[T>:Null<:AnyRef](klass:T){
def call(methodName:String, args:AnyRef *):AnyRef = {
def argtypes = args.map(_。getClass)
def method = klass.getClass.getMethod(methodName,argtypes:_ *)
方法。 invoke(klass,args:_ *)
}
}
implicit def anyref2callable [T>:Null<:AnyRef](klass:T):Caller [T] = new Caller )
a call(ca t,那里)
做这种事情会转换编译时错误进入运行时错误,它基本上规避了类型系统),所以谨慎使用。
(编辑:看到在上面的链接中使用NameTransformer - 添加,如果你尝试使用运算符。)
Assuming you have a string containing the name of a method, an object that supports that method and some arguments, is there some language feature that allows you to call that dynamically?
Kind of like Ruby's send
parameter.
You can do this with reflection in Java:
class A {
def cat(s1: String, s2: String) = s1 + " " + s2
}
val a = new A
val hi = "Hello"
val all = "World"
val method = a.getClass.getMethod("cat",hi.getClass,all.getClass)
method.invoke(a,hi,all)
And if you want it to be easy in Scala you can make a class that does this for you, plus an implicit for conversion:
case class Caller[T>:Null<:AnyRef](klass:T) {
def call(methodName:String,args:AnyRef*):AnyRef = {
def argtypes = args.map(_.getClass)
def method = klass.getClass.getMethod(methodName, argtypes: _*)
method.invoke(klass,args: _*)
}
}
implicit def anyref2callable[T>:Null<:AnyRef](klass:T):Caller[T] = new Caller(klass)
a call ("cat","Hi","there")
Doing this sort of thing converts compile-time errors into runtime errors, however (i.e. it essentially circumvents the type system), so use with caution.
(Edit: and see the use of NameTransformer in the link above--adding that will help if you try to use operators.)
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