From 6a4c9fc9fd6cb9ecf08bd5a22890eb19d22ad34e Mon Sep 17 00:00:00 2001
From: Aleksey Kladov <aleksey.kladov@gmail.com>
Date: Mon, 17 Aug 2020 16:11:29 +0200
Subject: [PATCH] Don't make fields private unless you have to

---
 crates/assists/src/lib.rs            | 37 ++++++++--------------------
 crates/rust-analyzer/src/handlers.rs |  4 +--
 crates/rust-analyzer/src/to_proto.rs |  8 +++---
 docs/dev/style.md                    | 29 ++++++++++++++++++++++
 4 files changed, 45 insertions(+), 33 deletions(-)

diff --git a/crates/assists/src/lib.rs b/crates/assists/src/lib.rs
index ae90d68a35..c589b08dc4 100644
--- a/crates/assists/src/lib.rs
+++ b/crates/assists/src/lib.rs
@@ -66,13 +66,13 @@ pub struct GroupLabel(pub String);
 
 #[derive(Debug, Clone)]
 pub struct Assist {
-    id: AssistId,
+    pub id: AssistId,
     /// Short description of the assist, as shown in the UI.
     label: String,
-    group: Option<GroupLabel>,
+    pub group: Option<GroupLabel>,
     /// Target ranges are used to sort assists: the smaller the target range,
     /// the more specific assist is, and so it should be sorted first.
-    target: TextRange,
+    pub target: TextRange,
 }
 
 #[derive(Debug, Clone)]
@@ -82,6 +82,11 @@ pub struct ResolvedAssist {
 }
 
 impl Assist {
+    fn new(id: AssistId, label: String, group: Option<GroupLabel>, target: TextRange) -> Assist {
+        assert!(label.starts_with(char::is_uppercase));
+        Assist { id, label, group, target }
+    }
+
     /// Return all the assists applicable at the given position.
     ///
     /// Assists are returned in the "unresolved" state, that is only labels are
@@ -114,30 +119,8 @@ impl Assist {
         acc.finish_resolved()
     }
 
-    pub(crate) fn new(
-        id: AssistId,
-        label: String,
-        group: Option<GroupLabel>,
-        target: TextRange,
-    ) -> Assist {
-        assert!(label.starts_with(|c: char| c.is_uppercase()));
-        Assist { id, label, group, target }
-    }
-
-    pub fn id(&self) -> AssistId {
-        self.id
-    }
-
-    pub fn label(&self) -> String {
-        self.label.clone()
-    }
-
-    pub fn group(&self) -> Option<GroupLabel> {
-        self.group.clone()
-    }
-
-    pub fn target(&self) -> TextRange {
-        self.target
+    pub fn label(&self) -> &str {
+        self.label.as_str()
     }
 }
 
diff --git a/crates/rust-analyzer/src/handlers.rs b/crates/rust-analyzer/src/handlers.rs
index 74f73655a4..e05ffc768e 100644
--- a/crates/rust-analyzer/src/handlers.rs
+++ b/crates/rust-analyzer/src/handlers.rs
@@ -859,10 +859,10 @@ pub(crate) fn handle_resolve_code_action(
         .map(|it| it.into_iter().filter_map(from_proto::assist_kind).collect());
 
     let assists = snap.analysis.resolved_assists(&snap.config.assist, frange)?;
-    let (id_string, index) = split_once(&params.id, ':').unwrap();
+    let (id, index) = split_once(&params.id, ':').unwrap();
     let index = index.parse::<usize>().unwrap();
     let assist = &assists[index];
-    assert!(assist.assist.id().0 == id_string);
+    assert!(assist.assist.id.0 == id);
     Ok(to_proto::resolved_code_action(&snap, assist.clone())?.edit)
 }
 
diff --git a/crates/rust-analyzer/src/to_proto.rs b/crates/rust-analyzer/src/to_proto.rs
index 8a2cfa2aee..535de2f71a 100644
--- a/crates/rust-analyzer/src/to_proto.rs
+++ b/crates/rust-analyzer/src/to_proto.rs
@@ -704,10 +704,10 @@ pub(crate) fn unresolved_code_action(
     index: usize,
 ) -> Result<lsp_ext::CodeAction> {
     let res = lsp_ext::CodeAction {
-        title: assist.label(),
-        id: Some(format!("{}:{}", assist.id().0.to_owned(), index.to_string())),
-        group: assist.group().filter(|_| snap.config.client_caps.code_action_group).map(|gr| gr.0),
-        kind: Some(code_action_kind(assist.id().1)),
+        title: assist.label().to_string(),
+        id: Some(format!("{}:{}", assist.id.0, index.to_string())),
+        group: assist.group.filter(|_| snap.config.client_caps.code_action_group).map(|gr| gr.0),
+        kind: Some(code_action_kind(assist.id.1)),
         edit: None,
         is_preferred: None,
     };
diff --git a/docs/dev/style.md b/docs/dev/style.md
index 963a6d73d0..8effddcda5 100644
--- a/docs/dev/style.md
+++ b/docs/dev/style.md
@@ -176,6 +176,35 @@ fn frobnicate(walrus: Option<Walrus>) {
 }
 ```
 
+# Getters & Setters
+
+If a field can have any value without breaking invariants, make the field public.
+Conversely, if there is an invariant, document it, enforce it in the "constructor" function, make the field private, and provide a getter.
+Never provide setters.
+
+Getters should return borrowed data:
+
+```
+struct Person {
+    // Invariant: never empty
+    first_name: String,
+    middle_name: Option<String>
+}
+
+// Good
+impl Person {
+    fn first_name(&self) -> &str { self.first_name.as_str() }
+    fn middle_name(&self) -> Option<&str> { self.middle_name.as_ref() }
+}
+
+// Not as good
+impl Person {
+    fn first_name(&self) -> String { self.first_name.clone() }
+    fn middle_name(&self) -> &Option<String> { &self.middle_name }
+}
+```
+
+
 # Premature Pessimization
 
 Avoid writing code which is slower than it needs to be.