doc: Runnable examples logging.

Also use //! Instead of /*! in liblog.

1 files changed, 148 insertions, 114 deletions

diff --git a/src/liblog/lib.rs b/src/liblog/lib.rs
index 0bad742933b..32222fb16ce 100644
--- a/src/liblog/lib.rs
+++ b/src/liblog/lib.rs
@@ -8,120 +8,154 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-/*!
-
-Utilities for program-wide and customizable logging
-
-## Example
-
-```
-#![feature(phase)]
-#[phase(plugin, link)] extern crate log;
-
-fn main() {
-    debug!("this is a debug {}", "message");
-    error!("this is printed by default");
-
-    if log_enabled!(log::INFO) {
-        let x = 3i * 4i; // expensive computation
-        info!("the answer was: {}", x);
-    }
-}
-```
-
-## Logging Macros
-
-There are five macros that the logging subsystem uses:
-
-* `log!(level, ...)` - the generic logging macro, takes a level as a u32 and any
-                       related `format!` arguments
-* `debug!(...)` - a macro hard-wired to the log level of `DEBUG`
-* `info!(...)` - a macro hard-wired to the log level of `INFO`
-* `warn!(...)` - a macro hard-wired to the log level of `WARN`
-* `error!(...)` - a macro hard-wired to the log level of `ERROR`
-
-All of these macros use the same style of syntax as the `format!` syntax
-extension. Details about the syntax can be found in the documentation of
-`std::fmt` along with the Rust tutorial/manual.
-
-If you want to check at runtime if a given logging level is enabled (e.g. if the
-information you would want to log is expensive to produce), you can use the
-following macro:
-
-* `log_enabled!(level)` - returns true if logging of the given level is enabled
-
-## Enabling logging
-
-Log levels are controlled on a per-module basis, and by default all logging is
-disabled except for `error!` (a log level of 1). Logging is controlled via the
-`RUST_LOG` environment variable. The value of this environment variable is a
-comma-separated list of logging directives. A logging directive is of the form:
-
-```text
-path::to::module=log_level
-```
-
-The path to the module is rooted in the name of the crate it was compiled for,
-so if your program is contained in a file `hello.rs`, for example, to turn on
-logging for this file you would use a value of `RUST_LOG=hello`.
-Furthermore, this path is a prefix-search, so all modules nested in the
-specified module will also have logging enabled.
-
-The actual `log_level` is optional to specify. If omitted, all logging will be
-enabled. If specified, the it must be either a numeric in the range of 1-255, or
-it must be one of the strings `debug`, `error`, `info`, or `warn`. If a numeric
-is specified, then all logging less than or equal to that numeral is enabled.
-For example, if logging level 3 is active, error, warn, and info logs will be
-printed, but debug will be omitted.
-
-As the log level for a module is optional, the module to enable logging for is
-also optional. If only a `log_level` is provided, then the global log level for
-all modules is set to this value.
-
-Some examples of valid values of `RUST_LOG` are:
-
-* `hello` turns on all logging for the 'hello' module
-* `info` turns on all info logging
-* `hello=debug` turns on debug logging for 'hello'
-* `hello=3` turns on info logging for 'hello'
-* `hello,std::option` turns on hello, and std's option logging
-* `error,hello=warn` turn on global error logging and also warn for hello
-
-## Filtering results
-
-A RUST_LOG directive may include a regex filter. The syntax is to append `/`
-followed by a regex. Each message is checked against the regex, and is only
-logged if it matches. Note that the matching is done after formatting the log
-string but before adding any logging meta-data. There is a single filter for all
-modules.
-
-Some examples:
-
-* `hello/foo` turns on all logging for the 'hello' module where the log message
-includes 'foo'.
-* `info/f.o` turns on all info logging where the log message includes 'foo',
-'f1o', 'fao', etc.
-* `hello=debug/foo*foo` turns on debug logging for 'hello' where the the log
-message includes 'foofoo' or 'fofoo' or 'fooooooofoo', etc.
-* `error,hello=warn/[0-9] scopes` turn on global error logging and also warn for
- hello. In both cases the log message must include a single digit number
- followed by 'scopes'
-
-## Performance and Side Effects
-
-Each of these macros will expand to code similar to:
-
-```rust,ignore
-if log_level <= my_module_log_level() {
-    ::log::log(log_level, format!(...));
-}
-```
-
-What this means is that each of these macros are very cheap at runtime if
-they're turned off (just a load and an integer comparison). This also means that
-if logging is disabled, none of the components of the log will be executed.
-
-*/
+//! Utilities for program-wide and customizable logging
+//!
+//! ## Example
+//!
+//! ```
+//! #![feature(phase)]
+//! #[phase(plugin, link)] extern crate log;
+//!
+//! fn main() {
+//!     debug!("this is a debug {}", "message");
+//!     error!("this is printed by default");
+//!
+//!     if log_enabled!(log::INFO) {
+//!         let x = 3i * 4i; // expensive computation
+//!         info!("the answer was: {}", x);
+//!     }
+//! }
+//! ```
+//!
+//! Assumes the binary is `main`:
+//!
+//! ```{.bash}
+//! $ RUST_LOG=error ./main
+//! ERROR:main: this is printed by default
+//! ```
+//!
+//! ```{.bash}
+//! $ RUST_LOG=info ./main
+//! ERROR:main: this is printed by default
+//! INFO:main: the answer was: 12
+//! ```
+//!
+//! ```{.bash}
+//! $ RUST_LOG=debug ./main
+//! DEBUG:main: this is a debug message
+//! ERROR:main: this is printed by default
+//! INFO:main: the answer was: 12
+//! ```
+//!
+//! You can also set the log level on a per module basis:
+//!
+//! ```{.bash}
+//! $ RUST_LOG=main=info ./main
+//! ERROR:main: this is printed by default
+//! INFO:main: the answer was: 12
+//! ```
+//!
+//! And enable all logging:
+//!
+//! ```{.bash}
+//! $ RUST_LOG=main ./main
+//! DEBUG:main: this is a debug message
+//! ERROR:main: this is printed by default
+//! INFO:main: the answer was: 12
+//! ```
+//!
+//!
+//! ## Logging Macros
+//!
+//! There are five macros that the logging subsystem uses:
+//!
+//! * `log!(level, ...)` - the generic logging macro, takes a level as a u32 and any
+//!                        related `format!` arguments
+//! * `debug!(...)` - a macro hard-wired to the log level of `DEBUG`
+//! * `info!(...)` - a macro hard-wired to the log level of `INFO`
+//! * `warn!(...)` - a macro hard-wired to the log level of `WARN`
+//! * `error!(...)` - a macro hard-wired to the log level of `ERROR`
+//!
+//! All of these macros use the same style of syntax as the `format!` syntax
+//! extension. Details about the syntax can be found in the documentation of
+//! `std::fmt` along with the Rust tutorial/manual.
+//!
+//! If you want to check at runtime if a given logging level is enabled (e.g. if the
+//! information you would want to log is expensive to produce), you can use the
+//! following macro:
+//!
+//! * `log_enabled!(level)` - returns true if logging of the given level is enabled
+//!
+//! ## Enabling logging
+//!
+//! Log levels are controlled on a per-module basis, and by default all logging is
+//! disabled except for `error!` (a log level of 1). Logging is controlled via the
+//! `RUST_LOG` environment variable. The value of this environment variable is a
+//! comma-separated list of logging directives. A logging directive is of the form:
+//!
+//! ```text
+//! path::to::module=log_level
+//! ```
+//!
+//! The path to the module is rooted in the name of the crate it was compiled for,
+//! so if your program is contained in a file `hello.rs`, for example, to turn on
+//! logging for this file you would use a value of `RUST_LOG=hello`.
+//! Furthermore, this path is a prefix-search, so all modules nested in the
+//! specified module will also have logging enabled.
+//!
+//! The actual `log_level` is optional to specify. If omitted, all logging will be
+//! enabled. If specified, the it must be either a numeric in the range of 1-255, or
+//! it must be one of the strings `debug`, `error`, `info`, or `warn`. If a numeric
+//! is specified, then all logging less than or equal to that numeral is enabled.
+//! For example, if logging level 3 is active, error, warn, and info logs will be
+//! printed, but debug will be omitted.
+//!
+//! As the log level for a module is optional, the module to enable logging for is
+//! also optional. If only a `log_level` is provided, then the global log level for
+//! all modules is set to this value.
+//!
+//! Some examples of valid values of `RUST_LOG` are:
+//!
+//! * `hello` turns on all logging for the 'hello' module
+//! * `info` turns on all info logging
+//! * `hello=debug` turns on debug logging for 'hello'
+//! * `hello=3` turns on info logging for 'hello'
+//! * `hello,std::option` turns on hello, and std's option logging
+//! * `error,hello=warn` turn on global error logging and also warn for hello
+//!
+//! ## Filtering results
+//!
+//! A RUST_LOG directive may include a regex filter. The syntax is to append `/`
+//! followed by a regex. Each message is checked against the regex, and is only
+//! logged if it matches. Note that the matching is done after formatting the log
+//! string but before adding any logging meta-data. There is a single filter for all
+//! modules.
+//!
+//! Some examples:
+//!
+//! * `hello/foo` turns on all logging for the 'hello' module where the log message
+//! includes 'foo'.
+//! * `info/f.o` turns on all info logging where the log message includes 'foo',
+//! 'f1o', 'fao', etc.
+//! * `hello=debug/foo*foo` turns on debug logging for 'hello' where the the log
+//! message includes 'foofoo' or 'fofoo' or 'fooooooofoo', etc.
+//! * `error,hello=warn/[0-9] scopes` turn on global error logging and also warn for
+//!  hello. In both cases the log message must include a single digit number
+//!  followed by 'scopes'
+//!
+//! ## Performance and Side Effects
+//!
+//! Each of these macros will expand to code similar to:
+//!
+//! ```rust,ignore
+//! if log_level <= my_module_log_level() {
+//!     ::log::log(log_level, format!(...));
+//! }
+//! ```
+//!
+//! What this means is that each of these macros are very cheap at runtime if
+//! they're turned off (just a load and an integer comparison). This also means that
+//! if logging is disabled, none of the components of the log will be executed.
 
 #![crate_name = "log"]
 #![experimental]