blocks|key|1271392|text|简而言之，您可以使用多个特征--它们是“可堆叠的”。另外，特征不能有构造函数参数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1271393|下面是特征是如何堆叠起来的。请注意，特征的顺序很重要。它们将从右到左相互呼叫。|1271394|class+Ball+{
++def+properties():+List[String]+=+List()
++override+def+toString()+=+"It's+a"+%2B
++++properties.mkString("+",+",+",+"+")+%2B
++++"ball"
}

trait+Red+extends+Ball+{
++override+def+properties()+=+super.properties+:::+List("red")
}

trait+Shiny+extends+Ball+{
++override+def+properties()+=+super.properties+:::+List("shiny")
}

object+Balls+{
++def+main(args:+Array[String])+{
++++val+myBall+=+new+Ball+with+Shiny+with+Red
++++println(myBall)+//+It's+a+shiny,+red+ball
++}
}|code-block|syntax|javascript|1271395|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

The short answer is that you can use multiple traits -- they are "stackable". Also, traits cannot have constructor parameters.

Here's how traits are stacked. Notice that the ordering of the traits are important. They will call each other from right to left.

<pre><code>class Ball {
 def properties(): List[String] = List()
 override def toString() = "It's a" +
 properties.mkString(" ", ", ", " ") +
 "ball"
}

trait Red extends Ball {
 override def properties() = super.properties ::: List("red")
}

trait Shiny extends Ball {
 override def properties() = super.properties ::: List("shiny")
}

object Balls {
 def main(args: Array[String]) {
 val myBall = new Ball with Shiny with Red
 println(myBall) // It's a shiny, red ball
 }
}
</code></pre>

blocks|key|1271443|text|这个site给出了一个很好的特征用法的例子。特征的一大优势是你可以扩展多个特征，但只能扩展一个抽象类。特征解决了多重继承的许多问题，但允许代码重用。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1271444|如果您了解ruby，则特征类似于混入。|1271445|entityMap|0|LINK|mutability|MUTABLE|url|http://markthomas.info/blog/?p=92^0|2|4|0|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@$A|O|B|P|1|Q]]|C|$]]|$1|D|3|E|5|6|7|R|8|@]|9|@]|C|$]]|$1|F|3|-4|5|6|7|S|8|@]|9|@]|C|$]]]|G|$H|$5|I|J|K|C|$L|M]]]]

This <a href="http://markthomas.info/blog/?p=92" rel="noreferrer">site</a> gives a good example of trait usage. One big advantage of traits is that you can extend multiple traits but only one abstract class. Traits solve many of the problems with multiple inheritance but allow code reuse. 

If you know ruby, traits are similar to mix-ins

blocks|key|1486045|text|这是我见过的最好的例子|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1486046|实践中的Scala+:组成特征-乐高风格：http://gleichmann.wordpress.com/2009/10/21/scala-in-practice-composing-traits-lego-style/|offset|length|1486047|++++class+Shuttle+extends+Spacecraft+with+ControlCabin+with+PulseEngine{

++++++++val+maxPulse+=+10

++++++++def+increaseSpeed+=+speedUp
++++}|code-block|syntax|javascript|1486048|entityMap|0|LINK|mutability|MUTABLE|url|http://gleichmann.wordpress.com/2009/10/21/scala-in-practice-composing-traits-lego-style/^0|0|L|2H|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@$D|U|E|V|1|W]]|A|$]]|$1|F|3|G|5|H|7|X|8|@]|9|@]|A|$I|J]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

This is the best example I've seen

Scala in practice: Composing Traits – Lego style:
<a href="http://gleichmann.wordpress.com/2009/10/21/scala-in-practice-composing-traits-lego-style/" rel="nofollow">http://gleichmann.wordpress.com/2009/10/21/scala-in-practice-composing-traits-lego-style/</a>

<pre><code> class Shuttle extends Spacecraft with ControlCabin with PulseEngine{

 val maxPulse = 10

 def increaseSpeed = speedUp
 }
</code></pre>

blocks|key|1486111|text|在将功能混合到类中时，特征非常有用。看看http://scalatest.org/吧。请注意，如何将各种领域特定语言(DSL)混合到一个测试类中。看看快速入门指南，看看Scalatest+(+http://scalatest.org/quick_start+)支持的一些数字用户线路。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1486112|entityMap|0|LINK|mutability|MUTABLE|url|http://scalatest.org/|1|http://scalatest.org/quick_start^0|K|L|0|2O|W|1|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@$A|O|B|P|1|Q]|$A|R|B|S|1|T]]|C|$]]|$1|D|3|-4|5|6|7|U|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]|L|$5|G|H|I|C|$J|M]]]]

Traits are useful for mixing functionality into a class. Take a look at <a href="http://scalatest.org/" rel="nofollow">http://scalatest.org/</a>. Note how you can mix in various domain-specific languages (DSL) into a test class. look at the quick start guide to look at some of the DSL's supported by Scalatest ( <a href="http://scalatest.org/quick_start" rel="nofollow">http://scalatest.org/quick_start</a> )

blocks|key|1271610|text|与Java中的接口类似，特征用于通过指定受支持方法的签名来定义对象类型。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1271611|与Java不同，Scala允许部分实现特征；也就是说，可以为某些方法定义默认实现。|1271612|与类相比，特征可能没有构造函数参数。特征类似于类，但它定义了函数和字段的接口，类可以提供具体的值和实现。|1271613|特征可以从其他特征或类继承。|1271614|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|L|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|M|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

Similar to interfaces in Java, traits are used to define object types by specifying the signature of the supported methods. 

Unlike Java, Scala allows traits to be partially implemented; i.e. it is possible to define default implementations for some methods. 

In contrast to classes, traits may not have constructor parameters.
Traits are like classes, but which define an interface of functions and fields that classes can supply concrete values and implementations.

Traits can inherit from other traits or from classes.

Can someone please explain traits in Scala? What are the advantages of traits over extending an abstract class?

What are the pros of using traits over abstract classes?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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有人能解释一下Scala中的特性吗？与扩展抽象类相比，特征的优势是什么？

问使用特征而不是抽象类的优点是什么？
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