From 30dea3a727879f9ed6cfe06433f1adb51765fa9e Mon Sep 17 00:00:00 2001
From: Aleksey Kladov <aleksey.kladov@gmail.com>
Date: Tue, 16 Mar 2021 10:51:05 +0300
Subject: [PATCH] Prefer match to if let else
---
docs/dev/style.md | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/docs/dev/style.md b/docs/dev/style.md
index c4eb7bc7ae6..e4a1672cab5 100644
--- a/docs/dev/style.md
+++ b/docs/dev/style.md
@@ -787,6 +787,27 @@ assert!(0 > x);
**Rationale:** Less-then comparisons are more intuitive, they correspond spatially to [real line](https://en.wikipedia.org/wiki/Real_line).
+## If-let
+
+Avoid `if let ... { } else { }` construct, use `match` instead.
+
+```rust
+// GOOD
+match ctx.expected_type.as_ref() {
+ Some(expected_type) => completion_ty == expected_type && !expected_type.is_unit(),
+ None => false,
+}
+
+// BAD
+if let Some(expected_type) = ctx.expected_type.as_ref() {
+ completion_ty == expected_type && !expected_type.is_unit()
+} else {
+ false
+}
+```
+
+**Rational:** `match` is almost always more compact.
+The `else` branch can get a more precise pattern: `None` or `Err(_)` instead of `_`.
## Token names