Imported Upstream version 1.1~hg20130304upstream/1.1_hg20130304

1 files changed, 52 insertions, 0 deletions

diff --git a/src/pkg/reflect/example_test.go b/src/pkg/reflect/example_test.go
new file mode 100644
index 000000000..62455c00a
--- /dev/null
+++ b/src/pkg/reflect/example_test.go
@@ -0,0 +1,52 @@
+// Copyright 2012 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package reflect_test
+
+import (
+	"fmt"
+	"reflect"
+)
+
+func ExampleMakeFunc() {
+	// swap is the implementation passed to MakeFunc.
+	// It must work in terms of reflect.Values so that it is possible
+	// to write code without knowing beforehand what the types
+	// will be.
+	swap := func(in []reflect.Value) []reflect.Value {
+		return []reflect.Value{in[1], in[0]}
+	}
+
+	// makeSwap expects fptr to be a pointer to a nil function.
+	// It sets that pointer to a new function created with MakeFunc.
+	// When the function is invoked, reflect turns the arguments
+	// into Values, calls swap, and then turns swap's result slice
+	// into the values returned by the new function.
+	makeSwap := func(fptr interface{}) {
+		// fptr is a pointer to a function.
+		// Obtain the function value itself (likely nil) as a reflect.Value
+		// so that we can query its type and then set the value.
+		fn := reflect.ValueOf(fptr).Elem()
+
+		// Make a function of the right type.
+		v := reflect.MakeFunc(fn.Type(), swap)
+
+		// Assign it to the value fn represents.
+		fn.Set(v)
+	}
+
+	// Make and call a swap function for ints.
+	var intSwap func(int, int) (int, int)
+	makeSwap(&intSwap)
+	fmt.Println(intSwap(0, 1))
+
+	// Make and call a swap function for float64s.
+	var floatSwap func(float64, float64) (float64, float64)
+	makeSwap(&floatSwap)
+	fmt.Println(floatSwap(2.72, 3.14))
+
+	// Output:
+	// 1 0
+	// 3.14 2.72
+}