From d79b22474cf9b02d0d3a0a78f8c6ef279770c36b Mon Sep 17 00:00:00 2001
From: Steve Klabnik <steve@steveklabnik.com>
Date: Wed, 3 Apr 2013 11:40:23 -0700
Subject: [PATCH] Add information about logging macros to the tutorial.
Closes #5699.
---
doc/rust.md | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/doc/rust.md b/doc/rust.md
index c6dba962676..eceb308b4f6 100644
--- a/doc/rust.md
+++ b/doc/rust.md
@@ -3251,6 +3251,28 @@ of runtime logging modules follows.
* `::rt::backtrace` Log a backtrace on task failure
* `::rt::callback` Unused
+#### Logging Expressions
+
+Rust provides several macros to log information. Here's a simple Rust program
+that demonstrates all four of them:
+
+```rust
+fn main() {
+ error!("This is an error log")
+ warn!("This is a warn log")
+ info!("this is an info log")
+ debug!("This is a dubug log")
+}
+```
+
+These four log levels correspond to levels 1-4, as controlled by `RUST_LOG`:
+
+```bash
+$ RUST_LOG=rust=3 ./rust
+rust: ~"\"This is na error log\""
+rust: ~"\"This is a warn log\""
+rust: ~"\"this is an info log\""
+```
# Appendix: Rationales and design tradeoffs