From 3291cb6c62c1d61178885c7af4b8c7f521aab04b Mon Sep 17 00:00:00 2001
From: "Dustin J. Mitchell" <djmitche@google.com>
Date: Thu, 16 Jan 2025 04:18:29 -0500
Subject: [PATCH] Make const slide less silly (#2557)
A constant named ZERO that does not contain zero seems pretty silly!
This also shows an example of a const fn.
---
src/user-defined-types/const.md | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/src/user-defined-types/const.md b/src/user-defined-types/const.md
index 102ca0c5..02ea6b5c 100644
--- a/src/user-defined-types/const.md
+++ b/src/user-defined-types/const.md
@@ -11,10 +11,18 @@ they are used:
```rust,editable
const DIGEST_SIZE: usize = 3;
-const ZERO: Option<u8> = Some(42);
+const FILL_VALUE: u8 = calculate_fill_value();
+
+const fn calculate_fill_value() -> u8 {
+ if DIGEST_SIZE < 10 {
+ 42
+ } else {
+ 13
+ }
+}
fn compute_digest(text: &str) -> [u8; DIGEST_SIZE] {
- let mut digest = [ZERO.unwrap_or(0); DIGEST_SIZE];
+ let mut digest = [FILL_VALUE; DIGEST_SIZE];
for (idx, &b) in text.as_bytes().iter().enumerate() {
digest[idx % DIGEST_SIZE] = digest[idx % DIGEST_SIZE].wrapping_add(b);
}