2 files changed, 29 insertions, 4 deletions
diff --git a/src/backend/dialoguer.rs b/src/backend/dialoguer.rs
index 11d5349..5bdebd6 100644
--- a/src/backend/dialoguer.rs
+++ b/src/backend/dialoguer.rs
@@ -1,7 +1,7 @@
 use crate::Backend;
-use crate::ValueBuilder;
 use crate::BuildableValue;
 use crate::CollectionBuilder;
+use crate::ValueBuilder;
 
 pub struct DialoguerBackend;
 
@@ -88,6 +88,9 @@ impl Backend for DialoguerBackend {
         Box::new(DialoguerVecBuilder::<T>(std::marker::PhantomData))
     }
 
+    fn option_builder<T: 'static + BuildableValue>(&self) -> Box<dyn CollectionBuilder<Output = Option<T>, Error = Self::Error>> {
+        Box::new(DialoguerOptionValueBuilder::<T>(std::marker::PhantomData))
+    }
 }
 
 pub struct DialoguerValueBuilder<T: Sized>(std::marker::PhantomData<T>);
@@ -106,6 +109,27 @@ impl<T> ValueBuilder for DialoguerValueBuilder<T>
     }
 }
 
+pub struct DialoguerOptionValueBuilder<T: BuildableValue>(std::marker::PhantomData<T>);
+impl<T: BuildableValue> CollectionBuilder for DialoguerOptionValueBuilder<T> {
+    type Output = Option<T>;
+    type Error = DialoguerBackendError;
+
+    fn build_collection(&self, value_desc: &str) -> Result<Self::Output, Self::Error> {
+        let q = format!("Do you want to provide a Value for {}", value_desc);
+        let b = dialoguer::Input::<bool>::new()
+            .with_prompt(q)
+            .interact_text()?;
+
+        if b {
+            T::builder(DialoguerBackend)
+                .build_value(value_desc)
+                .map(Some)
+        } else {
+            Ok(None)
+        }
+    }
+}
+
 
 pub struct DialoguerVecBuilder<T: 'static + BuildableValue>(std::marker::PhantomData<T>);
 impl<T> CollectionBuilder for DialoguerVecBuilder<T>
diff --git a/src/backend/mod.rs b/src/backend/mod.rs
index 1353a6d..3f72d66 100644
--- a/src/backend/mod.rs
+++ b/src/backend/mod.rs
@@ -1,8 +1,8 @@
 pub mod dialoguer;
 
-use crate::ValueBuilder;
 use crate::BuildableValue;
 use crate::CollectionBuilder;
+use crate::ValueBuilder;
 
 /// A backend can be used to get builders for specific types
 pub trait Backend {
@@ -26,9 +26,10 @@ pub trait Backend {
     fn char_builder(&self)   -> Box<dyn ValueBuilder<Output = char, Error = Self::Error>>;
     fn string_builder(&self) -> Box<dyn ValueBuilder<Output = String, Error = Self::Error>>;
 
+    fn option_builder<T: 'static + BuildableValue>(&self) -> Box<dyn CollectionBuilder<Output = Option<T>, Error = Self::Error>>;
+
     fn vec_builder<T>(&self) -> Box<dyn CollectionBuilder<Output = Vec<T>, Error = Self::Error>>
-        where T: 'static + BuildableValue
-            ;
+        where T: 'static + BuildableValue;
 }