Merge pull request #12 from devlights/csharp7-new-feature-pattern-variable-switch-statement

Add C# 7.0 Pattern variable with switch-statement example

Author: devlights

TryCSharp.Samples/CSharp7/PatternVariableWithSwitchStatement.cs

@@ -0,0 +1,61 @@
+using TryCSharp.Common;
+
+namespace TryCSharp.Samples.CSharp7
+{
+    [Sample]
+    public class PatternVariableWithSwitchStatement : IExecutable
+    {
+        public void Execute()
+        {
+            // C# 7.0 から　Pattern Variables の概念が導入された
+            // switch 文でもパターンが利用できるようになった
+            this.SwitchWithPattern(100);
+            this.SwitchWithPattern("hello");
+            this.SwitchWithPattern(true);
+            this.SwitchWithPattern(null);
+        }
+
+        private void SwitchWithPattern(object x)
+        {
+            // 型で振り分け
+            switch (x)
+            {
+                case int i:
+                    Output.WriteLine($"x is int: {i}");
+                    break;
+                case string s:
+                    Output.WriteLine($"x is string: {s}");
+                    break;
+                case bool b:
+                    Output.WriteLine($"x is bool: {b}");
+                    break;
+                case null:
+                    Output.WriteLine($"x is null");
+                    break;
+            }
+            
+            // case に when で条件を付けることが可能
+            switch (x)
+            {
+                case int i when i == 10:
+                    Output.WriteLine($"x is int, value is 10");
+                    break;
+                case int i when i == 100:
+                    Output.WriteLine($"x is int, value is 100");
+                    break;
+                case string s when s == "hello":
+                    Output.WriteLine($"x is string, value is hello");
+                    break;
+                case string s when s == "world":
+                    Output.WriteLine($"x is string, value is world");
+                    break;
+                case bool b when b == true:
+                    Output.WriteLine($"x is bool, value is true");
+                    break;
+                case bool b when b == false:
+                    Output.WriteLine($"x is bool, value is false");
+                    break;
+            }
+        }
+    }
+}