--- a/src/logging.rs	Sat Jul 12 17:17:37 2025 -0400
+++ b/src/logging.rs	Sat Jul 12 18:16:18 2025 -0400
@@ -15,6 +15,46 @@
 //! and may even itself implement `log::Log`, but that interface is not exposed
 //! to the generic PAM user.
 
+use crate::_doc::{man7, manbsd};
+use std::fmt;
+
+/// A trait for logging.
+pub trait Logger {
+    /// Logs something via this PAM handle.
+    ///
+    /// You probably want to use one of the logging macros,
+    /// like [`error!`](crate::error!),
+    /// [`warn!`](crate::warn!),
+    /// [`info!`](crate::info!),
+    /// or [`debug!`](crate::debug!).
+    ///
+    /// In most PAM implementations, this will go to syslog.
+    /// See [Linux-PAM's `pam_syslog`][man7] or
+    /// [OpenPAM's `openpam_log`][manbsd] for more details.
+    ///
+    /// # Example
+    ///
+    /// ```no_run
+    /// # use nonstick::PamShared;
+    /// use nonstick::logging::Level;
+    /// use nonstick::location;
+    /// # fn _test(pam_hdl: impl PamShared) {
+    /// # let delay_ms = 100;
+    /// # let url = "https://zombo.com";
+    /// // Usually, instead of calling this manually, just use the macros.
+    /// nonstick::error!(pam_hdl, "something bad happened!");
+    /// nonstick::warn!(pam_hdl, "loading information took {delay_ms} ms");
+    /// nonstick::info!(pam_hdl, "using network backend");
+    /// nonstick::debug!(pam_hdl, "sending GET request to {url}");
+    /// // But if you really want to, you can call this yourself:
+    /// pam_hdl.log(Level::Warn, location!(), format_args!("this is unnecessarily verbose"));
+    /// # }
+    /// ```
+    #[doc = man7!(3 pam_syslog)]
+    #[doc = manbsd!(3 openpam_log)]
+    fn log(&self, level: Level, loc: Location<'_>, entry: fmt::Arguments);
+}
+
 /// An entry to be added to the log.
 ///
 /// The levels are in descending order of importance and correspond roughly
@@ -167,15 +207,15 @@
 
     #[test]
     fn test_logging() {
-        struct Logger(RefCell<Vec<(Level, String)>>);
+        struct TestLog(RefCell<Vec<(Level, String)>>);
 
-        impl Logger {
+        impl Logger for TestLog {
             fn log(&self, level: Level, _: Location<'_>, text: fmt::Arguments) {
                 self.0.borrow_mut().push((level, text.to_string()))
             }
         }
 
-        let logger = Logger(Default::default());
+        let logger = TestLog(Default::default());
 
         let something = Level::Error;
         error!(logger, "here is another thing: {}", 99);