Add command-separation for PythonPreference display

crates/uv-python/src/discovery.rs

@@ -1490,45 +1490,74 @@ impl fmt::Display for PythonSource {
     }
 }
 
-impl fmt::Display for PythonPreference {
-    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
-        let s = match self {
-            Self::OnlyManaged => "managed installations",
+impl PythonPreference {
+    /// Return the sources that are considered when searching for a Python interpreter.
+    fn sources(self) -> &'static [&'static str] {
+        match self {
+            Self::OnlyManaged => &["managed installations"],
             Self::Managed | Self::Installed | Self::System => {
                 if cfg!(windows) {
-                    "managed installations, system path, or `py` launcher"
+                    &["managed installations", "system path", "`py` launcher"]
                 } else {
-                    "managed installations or system path"
+                    &["managed installations", "system path"]
                 }
             }
             Self::OnlySystem => {
                 if cfg!(windows) {
-                    "system path or `py` launcher"
+                    &["system path", "`py` launcher"]
                 } else {
-                    "system path"
+                    &["system path"]
                 }
             }
-        };
-        f.write_str(s)
+        }
+    }
+
+    /// Join a series of sources with commas and an "or" before the last source.
+    fn join_sources(sources: &[&str]) -> String {
+        match sources.len() {
+            1 => sources[0].to_string(),
+            2 => format!("{} or {}", sources[0], sources[1]),
+            _ => {
+                let last = sources.last().unwrap();
+                format!(
+                    "{}, or {}",
+                    sources.iter().take(sources.len() - 1).join(", "),
+                    last
+                )
+            }
+        }
+    }
+}
+
+impl fmt::Display for PythonPreference {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", Self::join_sources(self.sources()))
     }
 }
 
 impl fmt::Display for PythonNotFound {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        let sources = match self.environment_preference {
-            EnvironmentPreference::Any => {
-                format!("virtual environments or {}", self.python_preference)
-            }
-            EnvironmentPreference::ExplicitSystem => {
-                if self.request.is_explicit_system() {
-                    "virtual or system environment".to_string()
-                } else {
-                    "virtual environment".to_string()
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        let sources = {
+            let items: Vec<&str> = match self.environment_preference {
+                EnvironmentPreference::Any => ["virtual environments"]
+                    .into_iter()
+                    .chain(self.python_preference.sources().iter().copied())
+                    .collect(),
+                EnvironmentPreference::ExplicitSystem => {
+                    if self.request.is_explicit_system() {
+                        vec!["virtual", "system environment"]
+                    } else {
+                        vec!["virtual environment"]
+                    }
                 }
-            }
-            EnvironmentPreference::OnlySystem => self.python_preference.to_string(),
-            EnvironmentPreference::OnlyVirtual => "virtual environments".to_string(),
+                EnvironmentPreference::OnlySystem => {
+                    self.python_preference.sources().to_vec()
+                }
+                EnvironmentPreference::OnlyVirtual => vec!["virtual environments"],
+            };
+            PythonPreference::join_sources(&items)
         };
+
         match self.request {
             PythonRequest::Any => {
                 write!(f, "No interpreter found in {sources}")