--quiet and configurable default log level

src/lib.rs

@@ -5,9 +5,6 @@ use log::Level;
 /// # Examples
 ///
 /// ```rust
-/// extern crate clap_verbosity_flag;
-/// #[macro_use] extern crate structopt;
-///
 /// use structopt::StructOpt;
 /// use clap_verbosity_flag::Verbosity;
 ///
@@ -26,27 +23,62 @@ pub struct Verbosity {
     ///
     /// By default, it'll only report errors. Passing `-v` one time also prints
     /// warnings, `-vv` enables info logging, `-vvv` debug, and `-vvvv` trace.
-    #[structopt(long = "verbosity", short = "v", parse(from_occurrences))]
-    verbosity: u8,
+    #[structopt(long, short = "v", parse(from_occurrences))]
+    verbose: i8,
+
+    /// Pass many times for less log output
+    #[structopt(long, short = "q", parse(from_occurrences), conflicts_with = "verbose")]
+    quiet: i8,
+
+    #[structopt(skip)]
+    default: i8,
 }
 
 impl Verbosity {
+    /// Change the default level.
+    pub fn set_default(&mut self, level: Level) {
+        self.default = level_value(level);
+    }
+
     /// Get the log level.
     pub fn log_level(&self) -> Level {
-        match self.verbosity {
-            0 => Level::Error,
-            1 => Level::Warn,
-            2 => Level::Info,
-            3 => Level::Debug,
-            _ => Level::Trace,
-        }
+        level_enum(self.verbosity())
+    }
+
+    /// If the user requested complete silence (i.e. not just no-logging).
+    pub fn is_silent(&self) -> bool {
+        self.verbosity() < 0
+    }
+
+    fn verbosity(&self) -> i8 {
+        self.default - self.quiet + self.verbose
+    }
+}
+
+fn level_value(level: Level) -> i8 {
+    match level {
+        log::Level::Error => 0,
+        log::Level::Warn => 1,
+        log::Level::Info => 2,
+        log::Level::Debug => 3,
+        log::Level::Trace => 4,
+    }
+}
+
+fn level_enum(verbosity: i8) -> Level {
+    match verbosity {
+        std::i8::MIN..=0 => log::Level::Error,
+        1 => log::Level::Warn,
+        2 => log::Level::Info,
+        3 => log::Level::Debug,
+        4..=std::i8::MAX => log::Level::Trace,
     }
 }
 
 use std::fmt;
 
 impl fmt::Display for Verbosity {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "{}", self.verbosity)
+        write!(f, "{}", self.verbose)
     }
 }