add README

README.md

@@ -15,4 +15,38 @@ reflect api that avoids runtime reflect.Value cost
 
 [json-iterator](https://github.com/json-iterator/go) use this package to save runtime dispatching cost.
 This package is designed for low level libraries to optimize reflection performance.
-General application should still use reflect standard library.
+General application should still use reflect standard library.
+
+# reflect2.TypeByName
+
+```go
+// given package is github.com/your/awesome-package
+type MyStruct struct {
+	// ...
+}
+
+// will return the type
+reflect2.TypeByName("awesome-package.MyStruct")
+// however, if the type has not been used
+// it will be eliminated by compiler, so we can not get it in runtime
+```
+
+# reflect2 get/set interface{}
+
+```go
+valType := reflect2.TypeOf(1)
+i := 1
+j := 10
+valType.Set(&i, &j)
+// i will be 10
+```
+
+# reflect2 get/set unsafe.Pointer
+
+```go
+valType := reflect2.TypeOf(1)
+i := 1
+j := 10
+valType.UnsafeSet(unsfae.Pointer(&i), unsafe.Pointer(&j))
+// i will be 10
+```

reflect2.go

@@ -213,6 +213,9 @@ func TypeOfPtr(obj interface{}) PtrType {
 }
 
 func Type2(type1 reflect.Type) Type {
+	if type1 == nil {
+		return nil
+	}
 	return ConfigUnsafe.Type2(type1)
 }
 

type_map_test.go

@@ -0,0 +1,17 @@
+package reflect2_test
+
+import (
+	"github.com/modern-go/reflect2"
+	"testing"
+)
+
+type MyStruct struct {
+}
+
+func TestTypeByName(t *testing.T) {
+	typByPtr := reflect2.TypeOfPtr((*MyStruct)(nil)).Elem()
+	typByName := reflect2.TypeByName("reflect2_test.MyStruct")
+	if typByName != typByPtr {
+		t.Fail()
+	}
+}