Add {File,Terminal}LoggerDecorator

src/build.rs

@@ -22,9 +22,12 @@ pub trait Build {
     fn build(&self) -> Result<Logger>;
 }
 
+/// This trait allows to build a logger instance with a custom format (i.e., [`Drain`]}.
 pub trait BuildWithCustomFormat {
+    /// [`Decorator`] type generated by the logger builder.
     type Decorator: Decorator;
 
+    /// Builds a logger with a custom format.
     fn build_with_custom_format<F, D>(&self, f: F) -> Result<Logger>
     where
         F: FnOnce(Self::Decorator) -> Result<D>,

src/file.rs

@@ -179,22 +179,39 @@ impl Build for FileLoggerBuilder {
     }
 }
 impl BuildWithCustomFormat for FileLoggerBuilder {
-    type Decorator = PlainDecorator<FileAppender>;
+    type Decorator = FileLoggerDecorator;
 
     fn build_with_custom_format<F, D>(&self, f: F) -> Result<Logger>
     where
         F: FnOnce(Self::Decorator) -> Result<D>,
         D: Drain + Send + 'static,
         D::Err: Debug,
     {
-        let decorator = PlainDecorator::new(self.appender.clone());
+        let decorator = FileLoggerDecorator(PlainDecorator::new(self.appender.clone()));
         let drain = track!(f(decorator))?;
         Ok(self.common.build_with_drain(drain))
     }
 }
 
+/// [`slog_term::Decorator`] implementation for [`FileLoggerBuilder`].
+pub struct FileLoggerDecorator(PlainDecorator<FileAppender>);
+
+impl slog_term::Decorator for FileLoggerDecorator {
+    fn with_record<F>(
+        &self,
+        record: &slog::Record,
+        logger_values: &slog::OwnedKVList,
+        f: F,
+    ) -> io::Result<()>
+    where
+        F: FnOnce(&mut dyn slog_term::RecordDecorator) -> io::Result<()>,
+    {
+        self.0.with_record(record, logger_values, f)
+    }
+}
+
 #[derive(Debug)]
-pub struct FileAppender {
+struct FileAppender {
     path: PathBuf,
     file: Option<BufWriter<File>>,
     truncate: bool,

src/terminal.rs

@@ -121,20 +121,37 @@ impl Build for TerminalLoggerBuilder {
     }
 }
 impl BuildWithCustomFormat for TerminalLoggerBuilder {
-    type Decorator = Decorator;
+    type Decorator = TerminalLoggerDecorator;
 
     fn build_with_custom_format<F, D>(&self, f: F) -> Result<Logger>
     where
         F: FnOnce(Self::Decorator) -> Result<D>,
         D: Drain + Send + 'static,
         D::Err: Debug,
     {
-        let decorator = self.destination.to_decorator();
+        let decorator = TerminalLoggerDecorator(self.destination.to_decorator());
         let drain = track!(f(decorator))?;
         Ok(self.common.build_with_drain(drain))
     }
 }
 
+/// [`slog_term::Decorator`] implementation for [`TerminalLoggerBuilder`].
+pub struct TerminalLoggerDecorator(Decorator);
+
+impl slog_term::Decorator for TerminalLoggerDecorator {
+    fn with_record<F>(
+        &self,
+        record: &slog::Record,
+        logger_values: &slog::OwnedKVList,
+        f: F,
+    ) -> io::Result<()>
+    where
+        F: FnOnce(&mut dyn slog_term::RecordDecorator) -> io::Result<()>,
+    {
+        self.0.with_record(record, logger_values, f)
+    }
+}
+
 /// The destination to which log records will be outputted.
 ///
 /// # Examples
@@ -171,7 +188,7 @@ impl Destination {
     }
 }
 
-pub enum Decorator {
+enum Decorator {
     Term(TermDecorator),
     PlainStdout(PlainDecorator<io::Stdout>),
     PlainStderr(PlainDecorator<io::Stderr>),