Introduce a Verbosity type

Add it to your structopt type and you'll get a nice way to init
env_logger.

Author: killercup

docs/Readme.md

@@ -76,9 +76,9 @@ struct Cli {
     // Add a positional argument that the user has to supply:
     /// The file to read
     file: String,
-    /// Pass many times for more log output
-    #[structopt(long = "verbose", short = "v", parse(from_occurrences))]
-    verbosity: u8,
+    // Quick and easy logging setup you get for free with quicli
+    #[structopt(flatten)]
+    verbosity: Verbosity,
 }
 ```
 

docs/commit.md

@@ -76,9 +76,8 @@ struct Cli {
     /// How many?
     #[structopt(long = "amount", default_value = "3")]
     amount: i32,
-    /// Pass many times for more log output
-    #[structopt(long = "verbosity", short = "v", parse(from_occurrences))]
-    verbosity: u8,
+    #[structopt(flatten)]
+    verbosity: Verbosity,
 }
 ```
 

docs/thumbnails.md

@@ -75,9 +75,8 @@ Here we go:
 /// Make some thumbnails
 #[derive(Debug, StructOpt)]
 struct Cli {
-    /// Pass many times for more log output
-    #[structopt(long = "verbosity", short = "v", parse(from_occurrences))]
-    verbosity: u8,
+    #[structopt(flatten)]
+    verbosity: Verbosity,
 ```
 
 So far so typical for a _quicli_ app.

examples/Readme/src/main.rs

@@ -11,9 +11,9 @@ struct Cli {
     // Add a positional argument that the user has to supply:
     /// The file to read
     file: String,
-    /// Pass many times for more log output
-    #[structopt(long = "verbose", short = "v", parse(from_occurrences))]
-    verbosity: u8,
+    // Quick and easy logging setup you get for free with quicli
+    #[structopt(flatten)]
+    verbosity: Verbosity,
 }
 main!(|args: Cli, log_level: verbosity| {
     let content = read_file(&args.file)?;

examples/commit/src/main.rs

@@ -8,9 +8,8 @@ struct Cli {
     /// How many?
     #[structopt(long = "amount", default_value = "3")]
     amount: i32,
-    /// Pass many times for more log output
-    #[structopt(long = "verbosity", short = "v", parse(from_occurrences))]
-    verbosity: u8,
+    #[structopt(flatten)]
+    verbosity: Verbosity,
 }
 #[derive(Deserialize)]
 struct Commit {

examples/thumbnails/src/main.rs

@@ -4,9 +4,8 @@ use quicli::prelude::*;
 /// Make some thumbnails
 #[derive(Debug, StructOpt)]
 struct Cli {
-    /// Pass many times for more log output
-    #[structopt(long = "verbosity", short = "v", parse(from_occurrences))]
-    verbosity: u8,
+    #[structopt(flatten)]
+    verbosity: Verbosity,
     /// Which files?
     #[structopt(default_value = "*.jpg")]
     pattern: String,

examples/verbosity/src/main.rs

@@ -5,8 +5,8 @@ use quicli::prelude::*;
 /// Verbosity by any other name is still as verbose
 #[derive(Debug, StructOpt)]
 struct Cli {
-    #[structopt(long = "verbose", short = "v", parse(from_occurrences))]
-    team_rockets_blasting_off_again: u8,
+    #[structopt(flatten)]
+    team_rockets_blasting_off_again: Verbosity,
 }
 
 main!(|cli_args: Cli, log_level: team_rockets_blasting_off_again| {

src/lib.rs

@@ -31,6 +31,7 @@ extern crate rayon;
 #[cfg(feature = "full-throttle")]
 pub mod fs;
 mod main_macro;
+mod log_level;
 
 mod reexports {
     #[cfg(feature = "full-throttle")]
@@ -74,8 +75,5 @@ pub mod prelude {
     #[cfg(feature = "full-throttle")]
     pub use fs::*;
 
-    #[doc(hidden)]
-    pub use env_logger::Builder as LoggerBuilder;
-    #[doc(hidden)]
-    pub use log::Level as LogLevel;
+    pub use log_level::Verbosity;
 }

src/log_level.rs

@@ -0,0 +1,66 @@
+#![allow(missing_docs)]
+
+use log::{Level, LevelFilter};
+use env_logger::Builder as LoggerBuilder;
+use failure::Error;
+
+/// Easily add a `--verbose` flag to CLIs using Structopt
+///
+/// # Examples
+///
+/// ```rust
+/// extern crate quicli;
+/// #[macro_use] extern crate structopt;
+///
+/// use structopt::StructOpt;
+/// use quicli::prelude::Verbosity;
+///
+/// /// Le CLI
+/// #[derive(Debug, StructOpt)]
+/// struct Cli {
+///     #[structopt(flatten)]
+///     verbose: Verbosity,
+/// }
+/// #
+/// # fn main() {}
+/// ```
+#[derive(StructOpt, Debug)]
+pub struct Verbosity {
+    /// Pass many times for more log output
+    ///
+    /// 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,
+}
+
+impl Verbosity {
+    fn log_level(&self) -> LevelFilter {
+        match self.verbosity {
+            0 => Level::Error,
+            1 => Level::Warn,
+            2 => Level::Info,
+            3 => Level::Debug,
+            _ => Level::Trace,
+        }.to_level_filter()
+    }
+
+    /// Initialize `env_logger` and set the log level for the given package.
+    ///
+    /// All other modules default to printing warnings.
+    pub fn setup_env_logger(&self, own_pkg_name: &str) -> Result<(), Error> {
+        LoggerBuilder::new()
+            .filter(Some(&own_pkg_name.replace("-", "_")), self.log_level())
+            .filter(None, Level::Warn.to_level_filter())
+            .try_init()?;
+        Ok(())
+    }
+}
+
+use std::fmt;
+
+impl fmt::Display for Verbosity {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", self.verbosity)
+    }
+}

src/main_macro.rs

@@ -35,18 +35,7 @@ macro_rules! main {
         fn main() {
             fn run() -> $crate::prelude::Result<()> {
                 let $args = <$cli>::from_args();
-                let log_level = match $args.$verbosity {
-                    0 => $crate::prelude::LogLevel::Error,
-                    1 => $crate::prelude::LogLevel::Warn,
-                    2 => $crate::prelude::LogLevel::Info,
-                    3 => $crate::prelude::LogLevel::Debug,
-                    _ => $crate::prelude::LogLevel::Trace,
-                }.to_level_filter();
-
-                $crate::prelude::LoggerBuilder::new()
-                    .filter(Some(&env!("CARGO_PKG_NAME").replace("-", "_")), log_level)
-                    .filter(None, $crate::prelude::LogLevel::Warn.to_level_filter())
-                    .try_init()?;
+                $args.$verbosity.setup_env_logger(&env!("CARGO_PKG_NAME"))?;
 
                 $body