From 4d448d3ba4df1b16d2bea9e4fc28095fdcd1c0bd Mon Sep 17 00:00:00 2001
From: Sam Anthony <sam@samanthony.xyz>
Date: Thu, 19 Jan 2023 15:48:41 -0330
Subject: add convert() method to Volume trait

---
 src/volume.rs | 36 +++++++++++++++++++++++++++++-------
 1 file changed, 29 insertions(+), 7 deletions(-)

diff --git a/src/volume.rs b/src/volume.rs
index feeae14..675dfaa 100644
--- a/src/volume.rs
+++ b/src/volume.rs
@@ -9,15 +9,17 @@ pub trait Volume {
 
     fn set(&mut self, val: f64);
 
-    fn unit(&self) -> VolumeUnit;
+    fn unit(&self) -> Unit;
+
+    fn convert(self, unit: Unit) -> Box<dyn Volume>;
 }
 
-pub enum VolumeUnit {
+pub enum Unit {
     CubicMetre,
     Litre,
 }
 
-impl Display for VolumeUnit {
+impl Display for Unit {
     fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
         write!(
             f,
@@ -42,8 +44,21 @@ impl Volume for CubicMetre {
         self.0 = val;
     }
 
-    fn unit(&self) -> VolumeUnit {
-        VolumeUnit::CubicMetre
+    fn unit(&self) -> Unit {
+        Unit::CubicMetre
+    }
+
+    fn convert(self, unit: Unit) -> Box<dyn Volume> {
+        match unit {
+            Unit::CubicMetre => Box::new(self),
+            Unit::Litre => Box::new(Litre::from(self)),
+        }
+    }
+}
+
+impl From<Litre> for CubicMetre {
+    fn from(value: Litre) -> Self {
+        value.si()
     }
 }
 
@@ -59,8 +74,15 @@ impl Volume for Litre {
         self.0 = val
     }
 
-    fn unit(&self) -> VolumeUnit {
-        VolumeUnit::Litre
+    fn unit(&self) -> Unit {
+        Unit::Litre
+    }
+
+    fn convert(self, unit: Unit) -> Box<dyn Volume> {
+        match unit {
+            Unit::CubicMetre => Box::new(CubicMetre::from(self)),
+            Unit::Litre => Box::new(self),
+        }
     }
 }
 
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