如何獲得在指定類中混合的特徵列表？

Question

和更具體的例子：

abstract trait A 
trait B extends A 
trait C extends A 

如何檢查在指定的類漲跌互現什麼擴展性狀A（也可以是從0到許多）特質？

Answer 1

如何其他答案的混合

abstract trait A //interested in this one 
trait B extends A //and this one 
trait C extends A //this one too 
trait D //don't care about this one though 

val x = new A with B with D 
x.getClass.getInterfaces.filter(classOf[A].isAssignableFrom(_)) 

回報

Array[java.lang.Class[_]] = Array(interface A, interface B) 

Answer 2

scala> val x = new A with B with C 
x: java.lang.Object with A with B with C = $anon$1@8ea25fa 

scala> x.getClass.getInterfaces 
res11: Array[java.lang.Class[_]] = Array(interface A, interface B, interface C) 

Answer 3

怎麼是這樣的：

def getTraitsExtending(clazz:Class[_], baseTrait:Class[_]): Seq[Class[_]] = { 
    clazz.getInterfaces().filter { baseTrait isAssignableFrom _ } 
} 

此找到所有特質，clazz實現了自身的baseTrait subtraits。具有以下特點：

trait A 
trait B extends A 
trait C extends A 
trait D 

使用方法如下：

scala> val x1 = new C with B 
x1: java.lang.Object with C with B = $anon$1@51d92803 

scala> getTraitsExtending(x1.getClass, classOf[A]) 
res0: Seq[Class[_]] = WrappedArray(interface C, interface B) 

scala> val x2 = new C with A    
x2: java.lang.Object with C with A = $anon$1@f8db08 

scala> getTraitsExtending(x2.getClass, classOf[A]) 
res1: Seq[Class[_]] = WrappedArray(interface C, interface A) 

scala> val x3 = new C with D    
x3: java.lang.Object with C with D = $anon$1@2bbd83d 

scala> getTraitsExtending(x3.getClass, classOf[A]) 
res3: Seq[Class[_]] = WrappedArray(interface C) 

這僅着眼於那些直接由類傳入的實例實現的接口，但可以擴展到遞歸看建立繼承層次結構。