add code tabs in num10.

Author: benluo

_overviews/scala3-book/taste-methods.md

@@ -14,75 +14,123 @@ next-page: taste-functions
 Scala classes, case classes, traits, enums, and objects can all contain methods.
 The syntax of a simple method looks like this:
 
+{% tabs method_1 class=tabs-scala-version %}
+{% tab 'Scala 2 and 3' for=method_1 %}
 ```scala
 def methodName(param1: Type1, param2: Type2): ReturnType =
   // the method body
   // goes here
 ```
+{% endtab %}
+{% endtabs %}
 
 Here are a few examples:
 
+{% tabs method_2 class=tabs-scala-version %}
+{% tab 'Scala 2 and 3' for=method_2 %}
 ```scala
 def sum(a: Int, b: Int): Int = a + b
 def concatenate(s1: String, s2: String): String = s1 + s2
 ```
+{% endtab %}
+{% endtabs %}
 
 You don’t have to declare a method’s return type, so you can write those methods like this, if you prefer:
 
+{% tabs method_3 class=tabs-scala-version %}
+{% tab 'Scala 2 and 3' for=method_3 %}
 ```scala
 def sum(a: Int, b: Int) = a + b
 def concatenate(s1: String, s2: String) = s1 + s2
 ```
+{% endtab %}
+{% endtabs %}
 
 This is how you call those methods:
 
+{% tabs method_4 class=tabs-scala-version %}
+{% tab 'Scala 2 and 3' for=method_4 %}
 ```scala
 val x = sum(1, 2)
 val y = concatenate("foo", "bar")
 ```
+{% endtab %}
+{% endtabs %}
 
 Here’s an example of a multiline method:
 
+{% tabs method_5 class=tabs-scala-version %}
+{% tab 'Scala 2' for=method_5 %}
+```scala
+def getStackTraceAsString(t: Throwable): String = {
+  val sw = new StringWriter
+  t.printStackTrace(new PrintWriter(sw))
+  sw.toString
+}
+```
+{% endtab %}
+
+{% tab 'Scala 3' for=method_5 %}
 ```scala
 def getStackTraceAsString(t: Throwable): String =
   val sw = new StringWriter
   t.printStackTrace(new PrintWriter(sw))
   sw.toString
 ```
+{% endtab %}
+{% endtabs %}
 
 Method parameters can also have default values.
 In this example, the `timeout` parameter has a default value of `5000`:
 
+{% tabs method_6 class=tabs-scala-version %}
+{% tab 'Scala 2 and 3' for=method_6 %}
 ```scala
 def makeConnection(url: String, timeout: Int = 5000): Unit =
   println(s"url=$url, timeout=$timeout")
 ```
+{% endtab %}
+{% endtabs %}
 
 Because a default `timeout` value is supplied in the method declaration, the method can be called in these two ways:
 
+{% tabs method_7 class=tabs-scala-version %}
+{% tab 'Scala 2 and 3' for=method_7 %}
 ```scala
 makeConnection("https://localhost")         // url=http://localhost, timeout=5000
 makeConnection("https://localhost", 2500)   // url=http://localhost, timeout=2500
 ```
+{% endtab %}
+{% endtabs %}
 
 Scala also supports the use of _named parameters_ when calling a method, so you can also call that method like this, if you prefer:
 
+{% tabs method_8 class=tabs-scala-version %}
+{% tab 'Scala 2 and 3' for=method_8 %}
 ```scala
 makeConnection(
   url = "https://localhost",
   timeout = 2500
 )
 ```
+{% endtab %}
+{% endtabs %}
 
 Named parameters are particularly useful when multiple method parameters have the same type.
 At a glance, with this method you may wonder which parameters are set to `true` or `false`:
 
+{% tabs method_9 class=tabs-scala-version %}
+{% tab 'Scala 2 and 3' for=method_9 %}
 ```scala
 engage(true, true, true, false)
 ```
+{% endtab %}
+{% endtabs %}
 
 Without help from an IDE that code can be hard to read, but this code is much more obvious:
 
+{% tabs method_10 class=tabs-scala-version %}
+{% tab 'Scala 2 and 3' for=method_10 %}
 ```scala
 engage(
   speedIsSet = true,
@@ -91,14 +139,16 @@ engage(
   turnedOffParkingBrake = false
 )
 ```
-
-
+{% endtab %}
+{% endtabs %}
 
 ## Extension methods
 
 _Extension methods_ let you add new methods to closed classes.
 For instance, if you want to add two methods named `hello` and `aloha` to the `String` class, declare them as extension methods:
 
+{% tabs extension_1 class=tabs-scala-version %}
+{% tab 'Scala 3 only' for=extension_1 %}
 ```scala
 extension (s: String)
   def hello: String = s"Hello, ${s.capitalize}!"
@@ -107,6 +157,8 @@ extension (s: String)
 "world".hello    // "Hello, World!"
 "friend".aloha   // "Aloha, Friend!"
 ```
+{% endtab %}
+{% endtabs %}
 
 The `extension` keyword declares that you’re about to define one or more extension methods on the parameter that’s put in parentheses.
 As shown with this example, the parameter `s` of type `String` can then be used in the body of your extension methods.
@@ -115,6 +167,8 @@ This next example shows how to add a `makeInt` method to the `String` class.
 Here, `makeInt` takes a parameter named `radix`.
 The code doesn’t account for possible string-to-integer conversion errors, but skipping that detail, the examples show how it works:
 
+{% tabs extension_2 class=tabs-scala-version %}
+{% tab 'Scala 3 only' for=extension_2 %}
 ```scala
 extension (s: String)
   def makeInt(radix: Int): Int = Integer.parseInt(s, radix)
@@ -123,14 +177,12 @@ extension (s: String)
 "10".makeInt(2)     // Int = 2
 "100".makeInt(2)    // Int = 4
 ```
-
-
+{% endtab %}
+{% endtabs %}
 
 ## See also
 
 Scala Methods can be much more powerful: they can take type parameters and context parameters.
 They are covered in detail in the [Domain Modeling][data-1] section.
 
-
-
 [data-1]: {% link _overviews/scala3-book/domain-modeling-tools.md %}