Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "env_logger"
 edition = "2018"
-version = "0.8.4"
+version = "0.9.0"
 authors = ["The Rust Project Developers"]
 license = "MIT/Apache-2.0"
 readme = "README.md"

src/filter/mod.rs

@@ -238,7 +238,7 @@ impl Builder {
             });
         } else {
             // Consume map of directives.
-            let directives_map = mem::replace(&mut self.directives, HashMap::new());
+            let directives_map = mem::take(&mut self.directives);
             directives = directives_map
                 .into_iter()
                 .map(|(name, level)| Directive { name, level })
@@ -253,7 +253,7 @@ impl Builder {
         }
 
         Filter {
-            directives: mem::replace(&mut directives, Vec::new()),
+            directives: mem::take(&mut directives),
             filter: mem::replace(&mut self.filter, None),
         }
     }

src/fmt/mod.rs

@@ -141,6 +141,7 @@ pub(crate) type FormatFn = Box<dyn Fn(&mut Formatter, &Record) -> io::Result<()>
 pub(crate) struct Builder {
     pub format_timestamp: Option<TimestampPrecision>,
     pub format_module_path: bool,
+    pub format_target: bool,
     pub format_level: bool,
     pub format_indent: Option<usize>,
     pub custom_format: Option<FormatFn>,
@@ -152,7 +153,8 @@ impl Default for Builder {
     fn default() -> Self {
         Builder {
             format_timestamp: Some(Default::default()),
-            format_module_path: true,
+            format_module_path: false,
+            format_target: true,
             format_level: true,
             format_indent: Some(4),
             custom_format: None,
@@ -186,6 +188,7 @@ impl Builder {
                 let fmt = DefaultFormat {
                     timestamp: built.format_timestamp,
                     module_path: built.format_module_path,
+                    target: built.format_target,
                     level: built.format_level,
                     written_header_value: false,
                     indent: built.format_indent,
@@ -210,6 +213,7 @@ type SubtleStyle = &'static str;
 struct DefaultFormat<'a> {
     timestamp: Option<TimestampPrecision>,
     module_path: bool,
+    target: bool,
     level: bool,
     written_header_value: bool,
     indent: Option<usize>,
@@ -222,6 +226,7 @@ impl<'a> DefaultFormat<'a> {
         self.write_timestamp()?;
         self.write_level(record)?;
         self.write_module_path(record)?;
+        self.write_target(record)?;
         self.finish_header()?;
 
         self.write_args(record)
@@ -311,6 +316,17 @@ impl<'a> DefaultFormat<'a> {
         }
     }
 
+    fn write_target(&mut self, record: &Record) -> io::Result<()> {
+        if !self.target {
+            return Ok(());
+        }
+
+        match record.target() {
+            "" => Ok(()),
+            target => self.write_header_value(target),
+        }
+    }
+
     fn finish_header(&mut self) -> io::Result<()> {
         if self.written_header_value {
             let close_brace = self.subtle_style("]");
@@ -381,23 +397,33 @@ mod tests {
 
     use log::{Level, Record};
 
-    fn write(fmt: DefaultFormat) -> String {
+    fn write_record(record: Record, fmt: DefaultFormat) -> String {
         let buf = fmt.buf.buf.clone();
 
-        let record = Record::builder()
-            .args(format_args!("log\nmessage"))
-            .level(Level::Info)
-            .file(Some("test.rs"))
-            .line(Some(144))
-            .module_path(Some("test::path"))
-            .build();
-
         fmt.write(&record).expect("failed to write record");
 
         let buf = buf.borrow();
         String::from_utf8(buf.bytes().to_vec()).expect("failed to read record")
     }
 
+    fn write_target<'a>(target: &'a str, fmt: DefaultFormat) -> String {
+        write_record(
+            Record::builder()
+                .args(format_args!("log\nmessage"))
+                .level(Level::Info)
+                .file(Some("test.rs"))
+                .line(Some(144))
+                .module_path(Some("test::path"))
+                .target(target)
+                .build(),
+            fmt,
+        )
+    }
+
+    fn write(fmt: DefaultFormat) -> String {
+        write_target("", fmt)
+    }
+
     #[test]
     fn format_with_header() {
         let writer = writer::Builder::new()
@@ -409,6 +435,7 @@ mod tests {
         let written = write(DefaultFormat {
             timestamp: None,
             module_path: true,
+            target: false,
             level: true,
             written_header_value: false,
             indent: None,
@@ -430,6 +457,7 @@ mod tests {
         let written = write(DefaultFormat {
             timestamp: None,
             module_path: false,
+            target: false,
             level: false,
             written_header_value: false,
             indent: None,
@@ -451,6 +479,7 @@ mod tests {
         let written = write(DefaultFormat {
             timestamp: None,
             module_path: true,
+            target: false,
             level: true,
             written_header_value: false,
             indent: Some(4),
@@ -472,6 +501,7 @@ mod tests {
         let written = write(DefaultFormat {
             timestamp: None,
             module_path: true,
+            target: false,
             level: true,
             written_header_value: false,
             indent: Some(0),
@@ -493,6 +523,7 @@ mod tests {
         let written = write(DefaultFormat {
             timestamp: None,
             module_path: false,
+            target: false,
             level: false,
             written_header_value: false,
             indent: Some(4),
@@ -514,6 +545,7 @@ mod tests {
         let written = write(DefaultFormat {
             timestamp: None,
             module_path: false,
+            target: false,
             level: false,
             written_header_value: false,
             indent: None,
@@ -535,6 +567,7 @@ mod tests {
         let written = write(DefaultFormat {
             timestamp: None,
             module_path: false,
+            target: false,
             level: false,
             written_header_value: false,
             indent: Some(4),
@@ -544,4 +577,76 @@ mod tests {
 
         assert_eq!("log\n\n    message\n\n", written);
     }
+
+    #[test]
+    fn format_target() {
+        let writer = writer::Builder::new()
+            .write_style(WriteStyle::Never)
+            .build();
+
+        let mut f = Formatter::new(&writer);
+
+        let written = write_target(
+            "target",
+            DefaultFormat {
+                timestamp: None,
+                module_path: true,
+                target: true,
+                level: true,
+                written_header_value: false,
+                indent: None,
+                suffix: "\n",
+                buf: &mut f,
+            },
+        );
+
+        assert_eq!("[INFO  test::path target] log\nmessage\n", written);
+    }
+
+    #[test]
+    fn format_empty_target() {
+        let writer = writer::Builder::new()
+            .write_style(WriteStyle::Never)
+            .build();
+
+        let mut f = Formatter::new(&writer);
+
+        let written = write(DefaultFormat {
+            timestamp: None,
+            module_path: true,
+            target: true,
+            level: true,
+            written_header_value: false,
+            indent: None,
+            suffix: "\n",
+            buf: &mut f,
+        });
+
+        assert_eq!("[INFO  test::path] log\nmessage\n", written);
+    }
+
+    #[test]
+    fn format_no_target() {
+        let writer = writer::Builder::new()
+            .write_style(WriteStyle::Never)
+            .build();
+
+        let mut f = Formatter::new(&writer);
+
+        let written = write_target(
+            "target",
+            DefaultFormat {
+                timestamp: None,
+                module_path: true,
+                target: false,
+                level: true,
+                written_header_value: false,
+                indent: None,
+                suffix: "\n",
+                buf: &mut f,
+            },
+        );
+
+        assert_eq!("[INFO  test::path] log\nmessage\n", written);
+    }
 }

src/lib.rs

@@ -97,28 +97,38 @@
 //! directives*. A logging directive is of the form:
 //!
 //! ```text
-//! path::to::module=level
+//! example::log::target=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 log target is typically equal to the path of the module the message
+//! in question originated from, though it can be overriden.
+//!
+//! The path is rooted in the name of the crate it was compiled for, so if
+//! your program is in a file called, for example, `hello.rs`, the path would
+//! simply be be `hello`.
+//!
+//! Furthermore, the the log can be filtered using prefix-search based on the
+//! specified log target. A value of, for example, `RUST_LOG=example`, would
+//! match all of the messages with targets:
+//!
+//! * `example`
+//! * `example::test`
+//! * `example::test::module::submodule`
+//! * `examples::and_more_examples`
 //!
 //! When providing the crate name or a module path, explicitly specifying the
-//! log level is optional. If omitted, all logging for the item (and its
-//! children) will be enabled.
+//! log level is optional. If omitted, all logging for the item will be
+//! enabled.
 //!
 //! The names of the log levels that may be specified correspond to the
 //! variations of the [`log::Level`][level-enum] enum from the `log`
 //! crate. They are:
 //!
-//!    * `error`
-//!    * `warn`
-//!    * `info`
-//!    * `debug`
-//!    * `trace`
+//! * `error`
+//! * `warn`
+//! * `info`
+//! * `debug`
+//! * `trace`
 //!
 //! There is also a pseudo logging level, `off`, which may be specified to
 //! disable all logging for a given module or for the entire application. As
@@ -260,7 +270,7 @@
 //! env_logger::Builder::from_env(Env::default().default_filter_or("warn")).init();
 //! ```
 //!
-//! [gh-repo-examples]: https://github.com/env-logger-rs/env_logger/tree/master/examples
+//! [gh-repo-examples]: https://github.com/env-logger-rs/env_logger/tree/main/examples
 //! [level-enum]: https://docs.rs/log/latest/log/enum.Level.html
 //! [log-crate-url]: https://docs.rs/log/
 //! [`Builder`]: struct.Builder.html
@@ -598,6 +608,12 @@ impl Builder {
         self
     }
 
+    /// Whether or not to write the target in the default format.
+    pub fn format_target(&mut self, write: bool) -> &mut Self {
+        self.format.format_target = write;
+        self
+    }
+
     /// Configures the amount of spaces to use to indent multiline log records.
     /// A value of `None` disables any kind of indentation.
     pub fn format_indent(&mut self, indent: Option<usize>) -> &mut Self {