val: add TryGet() methodv0.1.0

2 files changed, 37 insertions, 0 deletions

diff --git a/val.go b/val.go
index 4d35fb9..2b762cb 100644
--- a/val.go
+++ b/val.go
@@ -47,6 +47,19 @@ func (v Val[T]) Get() T {
 	return <-c
 }
 
+// TryGet returns the stored value if it has already been set, or false if it hasn't.
+func (v Val[T]) TryGet() (*T, bool) {
+	c := make(chan T)
+	defer close(c)
+	select {
+	case v.Request <- c:
+		val := <-c
+		return &val, true
+	default:
+		return nil, false
+	}
+}
+
 func (v Val[T]) Close() {
 	close(v.Request)
 	close(v.Set)
diff --git a/val_test.go b/val_test.go
index 188f8a8..c1b7766 100644
--- a/val_test.go
+++ b/val_test.go
@@ -34,6 +34,30 @@ func TestValSetRemote(t *testing.T) {
 	<-done
 }
 
+// Val.TryGet() before Set should fail.
+func TestValTryGetFail(t *testing.T) {
+	sv := share.NewVal[int]() // type is arbitrary
+	defer sv.Close()
+	if v, ok := sv.TryGet(); ok {
+		t.Errorf("Val.TryGet() succeeded (returned %v) before value was set; expected to fail", v)
+	}
+}
+
+// Val.TryGet() after Set should succeed.
+func TestValTryGet(t *testing.T) {
+	sv := share.NewVal[string]()
+	defer sv.Close()
+	v := "foo"
+	sv.Set <- v
+	ret, ok := sv.TryGet()
+	if !ok {
+		t.Error("Val.TryGet() failed")
+	}
+	if *ret != v {
+		t.Errorf("Val.TryGet() returned %v; expected %v", ret, v)
+	}
+}
+
 func verifySameVal[T comparable](sv share.Val[T], v T, t *testing.T) {
 	ret := sv.Get()
 	if ret != v {