From dba7e48413995b50c0181fca8cca7d9d96fb3347 Mon Sep 17 00:00:00 2001
From: Momchil Atanasov <momchil.dev@gmail.com>
Date: Sun, 10 Mar 2024 19:59:00 +0200
Subject: [PATCH] Add ValueOrDefault to optional type (#30)

---
 opt/value.go      | 9 +++++++++
 opt/value_test.go | 7 +++++++
 2 files changed, 16 insertions(+)

diff --git a/opt/value.go b/opt/value.go
index 130807b..ba57b45 100644
--- a/opt/value.go
+++ b/opt/value.go
@@ -10,6 +10,15 @@ type T[D any] struct {
 	Value D
 }
 
+// ValueOrDefault returns the value held in this optional if it is specified,
+// otherwise it returns the given fallback value.
+func (t T[D]) ValueOrDefault(fallback D) D {
+	if t.Specified {
+		return t.Value
+	}
+	return fallback
+}
+
 // ToPtr returns a pointer-based representation of the value held
 // in this optional. If this optional is not specified, then nil
 // is returned.
diff --git a/opt/value_test.go b/opt/value_test.go
index 1865e99..3308541 100644
--- a/opt/value_test.go
+++ b/opt/value_test.go
@@ -32,6 +32,13 @@ var _ = Describe("Optional", func() {
 		Expect(v.Value).To(Equal(actual))
 	})
 
+	It("is possible to get a fallback value", func() {
+		v := opt.Unspecified[string]()
+		Expect(v.ValueOrDefault("fallback")).To(Equal("fallback"))
+		v = opt.V("hello")
+		Expect(v.ValueOrDefault("fallback")).To(Equal("hello"))
+	})
+
 	It("is possible to get a pointer representation of an unspecified value", func() {
 		v := opt.Unspecified[string]()
 		ptr := v.ToPtr()