feat: support V

generic.go

@@ -3,6 +3,14 @@
 package pt
 
 // P return pointer of v
-func P[V any](v V) *V {
+func P[T any](v T) *T {
 	return &v
 }
+
+// V return value of p
+func V[T any](p *T) T {
+	if p == nil {
+		return *new(T)
+	}
+	return *p
+}

generic_test.go

@@ -10,37 +10,51 @@ import (
 )
 
 func TestP(t *testing.T) {
-	type args struct {
-		v any
-	}
-	tests := []struct {
-		name string
-		args args
-	}{
-		{
-			name: "int",
-			args: args{
-				v: 1,
-			},
-		},
-		{
-			name: "float64",
-			args: args{
-				v: 1.1,
-			},
-		},
-		{
-			name: "time",
-			args: args{
-				v: time.Now(),
-			},
-		},
-	}
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			if got := pt.P(tt.args.v); *got != tt.args.v {
-				t.Errorf("P() = %v, want %v", got, tt.args.v)
-			}
-		})
-	}
+	t.Run("int", func(t *testing.T) {
+		if got := pt.P(1); *got != 1 {
+			t.Errorf("P() = %v, want %v", *got, 1)
+		}
+	})
+	t.Run("float64", func(t *testing.T) {
+		if got := pt.P(1.1); *got != 1.1 {
+			t.Errorf("P() = %v, want %v", *got, 1)
+		}
+	})
+	t.Run("time", func(t *testing.T) {
+		now := time.Now()
+		if got := pt.P(now); *got != now {
+			t.Errorf("P() = %v, want %v", *got, 1)
+		}
+	})
+}
+
+func TestV(t *testing.T) {
+	t.Run("int", func(t *testing.T) {
+		if got := pt.V(pt.P(1)); got != 1 {
+			t.Errorf("V() = %v, want %v", got, 1)
+		}
+	})
+	t.Run("float64", func(t *testing.T) {
+		if got := pt.V(pt.P(1.1)); got != 1.1 {
+			t.Errorf("V() = %v, want %v", got, 1)
+		}
+	})
+	t.Run("time", func(t *testing.T) {
+		now := time.Now()
+		if got := pt.V(pt.P(now)); got != now {
+			t.Errorf("V() = %v, want %v", got, 1)
+		}
+	})
+	t.Run("nil int", func(t *testing.T) {
+		var i *int
+		if got := pt.V(i); got != 0 {
+			t.Errorf("V() = %v, want %v", got, 0)
+		}
+	})
+	t.Run("nil string", func(t *testing.T) {
+		var s *string
+		if got := pt.V(s); got != "" {
+			t.Errorf("V() = %v, want %v", got, "")
+		}
+	})
 }