improvements, add example, readme

.gitignore

@@ -1,2 +1,3 @@
 /target
 Cargo.lock
+.idea

Cargo.toml

@@ -1,17 +1,26 @@
 [package]
-name = "appbase"
+name = "clappconfig"
 version = "0.1.0"
 authors = ["Ondřej Hruška <ondra@ondrovo.com>"]
 edition = "2018"
-publish = false
-
-# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+license = "MIT"
+description = "Clap-based app config boilerplate: set up logging, load config, parse args"
+repository = "https://git.ondrovo.com/packages/cli-app-base"
+readme = "README.md"
+keywords = ["clap", "cli", "logging", "boilerplate"]
+categories = [
+    "command-line-interface"
+]
 
 [dependencies]
 log = "0.4"
-env_logger = "0.7.1"
+env_logger = "0.7"
 failure = "0.1"
-serde = "1.0.106"
-serde_json = "1.0.51"
-clap = "2.33.0"
-json5 = "0.2.7"
+serde = "1.0"
+serde_json = "1.0"
+clap = "2.33"
+json5 = "0.2"
+
+[dev-dependencies]
+smart-default = "0.6"
+serde_derive = "1.0"

README.md

@@ -0,0 +1,59 @@
+# clappconfig - CLI app config boilerplate
+
+```none
+Clap
+  App
+     Config
+-----------
+clappconfig
+```
+
+This crate provides a simple CLI app boilerplate that takes care of 
+the most repetitive init tasks:
+
+- Load JSON5 config from a custom or default path (or use `Default::default()`)
+- Set up logging, with CLI and config-based overrides
+- Optionally print the loaded or default config
+- Show help / version on demand, courtesy of `clap`
+- Optional start-up banner print
+
+Supports custom `clap` arguments as well.
+
+-> The repository is open to improvement PRs.
+
+## Logging
+
+- uses `env_logger` by default
+- level can be set in the config file
+- log level can be overridden by the `--log` CLI flag
+- log level can be increased by repeated use of `-v` or `--verbose`
+
+## Example
+
+See the examples directory.
+
+The example called "rotn" implements rot13 as a command-line tool.
+
+```none
+$ cargo run --example complete -- -h
+
+Rot-N 0.1.0 by Ondřej Hruška <ondra@ondrovo.com>
+
+USAGE:
+    rotn [FLAGS] [OPTIONS] --input <FILE>
+
+FLAGS:
+        --default-config    Print the default config JSON for reference (or to be piped to a file)
+        --dump-config       Print the loaded config struct
+    -h, --help              Prints help information
+    -V, --version           Prints version information
+    -v, --verbose           Increase logging verbosity (repeat to increase)
+
+OPTIONS:
+    -c, --config <FILE>    Sets a custom config file (JSON5)
+    -i, --input <FILE>     Input file
+        --log <LEVEL>      Set logging verbosity (error,warning,info,debug,trace)
+    -n, --shift <N>        Positive or negative shift, default 13
+```
+
+To get rot13 of this README, run `cargo run --example rotn -- -iREADME.md`.

examples/foo.json

@@ -0,0 +1,5 @@
+// This is a JSON5 file with config for the "minimal.rs" example
+{
+  // a foo
+  "foo": 1234,
+}

examples/minimal.rs

@@ -0,0 +1,41 @@
+#[macro_use]
+extern crate serde_derive;
+#[macro_use]
+extern crate log;
+
+use clap::ArgMatches;
+use clappconfig::AppConfig;
+use failure::Fallible;
+
+#[derive(Serialize, Deserialize, Debug, Default)]
+#[serde(default)]
+struct Config {
+    foo: u32,
+    bar: u32,
+}
+
+impl AppConfig for Config {
+    type Init = Config;
+
+    fn logging(&self) -> &str {
+        "info"
+    }
+
+    fn configure<'a>(self, _clap: &ArgMatches<'a>) -> Fallible<Config> {
+        Ok(self)
+    }
+}
+
+fn main() -> Fallible<()> {
+    let cfg = Config::init("Foo", "examples/foo.json", None)?;
+
+    trace!("Trace message");
+    debug!("Debug message");
+    info!("Info message");
+    warn!("Warn message");
+    error!("Error message");
+
+    println!("Welcome to foo, config:\n{:#?}", cfg);
+
+    Ok(())
+}

examples/rotn.rs

@@ -0,0 +1,159 @@
+#[macro_use]
+extern crate serde_derive;
+#[macro_use]
+extern crate failure;
+#[macro_use]
+extern crate log;
+
+use clap::ArgMatches;
+use clappconfig::AppConfig;
+use failure::Fallible;
+use smart_default::SmartDefault;
+use std::collections::HashMap;
+use std::fs::OpenOptions;
+use std::io::Read;
+use std::path::PathBuf;
+use std::str::FromStr;
+
+#[derive(Serialize, Deserialize, Debug, SmartDefault)]
+#[serde(deny_unknown_fields)]
+#[serde(default)]
+struct Config {
+    #[default = "info"]
+    logging: String,
+    log_modules: HashMap<String, String>,
+
+    #[default = 13]
+    offset: i32,
+}
+
+struct Main {
+    config: Config,
+    input_file: PathBuf,
+}
+
+impl AppConfig for Config {
+    type Init = Main;
+
+    fn logging(&self) -> &str {
+        &self.logging
+    }
+
+    fn logging_suppress_mods(&self) -> Option<Vec<&str>> {
+        Some(vec![
+            "tokio_reactor",
+            "tokio_io",
+            "hyper",
+            "reqwest",
+            "mio",
+            "want",
+        ])
+    }
+
+    /// Print startup banner.
+    /// May be overridden to customize or disable it.
+    fn print_banner(_name: &str, _version: &str) {
+        // Disable
+    }
+
+    /// Log messages printed before logging is set up
+    /// May be overridden to customize or disable it.
+    fn pre_log_println(_message: String) {
+        // Disable
+    }
+
+    /// Get log module levels to use (take priority over the main log level)
+    fn logging_mod_levels(&self) -> Option<&HashMap<String, String>> {
+        Some(&self.log_modules)
+    }
+
+    fn add_args<'a: 'b, 'b>(clap: clap::App<'a, 'b>) -> clap::App<'a, 'b> {
+        // Default impl
+        clap.arg(
+            clap::Arg::with_name("input")
+                .short("i")
+                .long("input")
+                .value_name("FILE")
+                .required_unless("default-config")
+                .help("Input file")
+                .takes_value(true),
+        )
+        .arg(
+            clap::Arg::with_name("offset")
+                .short("n")
+                .long("shift")
+                .value_name("N")
+                .help("Positive or negative shift, default 13")
+                .takes_value(true),
+        )
+    }
+
+    fn configure<'a>(mut self, clap: &ArgMatches<'a>) -> Fallible<Self::Init> {
+        let input = clap.value_of("input").unwrap().to_string();
+
+        debug!("Input: {}", input);
+
+        if input.is_empty() {
+            bail!("Input is required!");
+        }
+
+        let pb = PathBuf::from_str(&input)?.canonicalize()?;
+
+        debug!("Input path: {}", pb.display());
+
+        if !pb.is_file() {
+            return Err(format_err!("Input is not a file!"));
+        }
+
+        // Set offset by arg
+        if let Some(v) = clap.value_of("offset") {
+            self.offset = v.parse()?;
+        }
+
+        debug!("Rot raw: {}", self.offset);
+
+        self.offset = i32::rem_euclid(self.offset, 26);
+
+        debug!("Rot normalized: {}", self.offset);
+
+        Ok(Main {
+            config: self,
+            input_file: pb,
+        })
+    }
+}
+
+fn rot_n(string: String, rot: u8) -> String {
+    assert!(rot < 26);
+    const LOWER: &[u8] = b"abcdefghihjlmnopqrstuvwxyz";
+    const UPPER: &[u8] = b"ABCDEFGHIHJLMNOPQRSTUVWXYZ";
+
+    string
+        .chars()
+        .map(|c| match c {
+            'A'..='Z' => UPPER[((c as u8 - 'A' as u8 + rot) % 26) as usize] as char,
+            'a'..='z' => LOWER[((c as u8 - 'a' as u8 + rot) % 26) as usize] as char,
+            _ => c,
+        })
+        .collect()
+}
+
+fn main() -> Fallible<()> {
+    // Using custom version (default is CARGO_PKG_VERSION)
+    let version = format!(
+        "{} by {}",
+        env!("CARGO_PKG_VERSION"),
+        env!("CARGO_PKG_AUTHORS")
+    );
+
+    let main = Config::init("Rot-N", "rotn_config.json", Some(&version))?;
+
+    let mut f = OpenOptions::new().read(true).open(main.input_file)?;
+
+    let mut buf = String::new();
+    f.read_to_string(&mut buf)?;
+
+    println!("{}", rot_n(buf, main.config.offset as u8));
+
+    Ok(())
+}

src/lib.rs

@@ -18,7 +18,19 @@ pub trait AppConfig: Sized + Serialize + DeserializeOwned + Debug + Default {
     type Init;
 
     /// Get log level
-    fn logging(&self) -> &String;
+    fn logging(&self) -> &str;
+
+    /// Print startup banner.
+    /// May be overridden to customize or disable it.
+    fn print_banner(name: &str, version: &str) {
+        println!("{} {}\nRun with -h for help", name, version);
+    }
+
+    /// Log messages printed before logging is set up
+    /// May be overridden to customize or disable it.
+    fn pre_log_println(message: String) {
+        println!("{}", message);
+    }
 
     /// Get names of library modules to suppress from log output (limit to warn or error)
     fn logging_suppress_mods(&self) -> Option<Vec<&str>> {
@@ -103,25 +115,26 @@ pub trait AppConfig: Sized + Serialize + DeserializeOwned + Debug + Default {
         /* Load config */
         let cfg_file = argv.value_of("config").unwrap_or(cfg_file_name);
 
-        println!("{} {}\nRun with -h for help", name, version);
+        Self::print_banner(name, version);
 
         let filepath = PathBuf::from_str(cfg_file)?;
 
         let config: Self = if filepath.is_file() {
-            println!("Load config from \"{}\"", cfg_file);
+            let path = filepath.canonicalize()?;
+            Self::pre_log_println(format!("Loading config from: {}", path.display()));
 
-            let buf = read_file(filepath)?;
+            let buf = read_file(path)?;
             json5::from_str(&buf)?
         } else {
-            println!(
+            Self::pre_log_println(format!(
                 "Config file \"{}\" does not exist, using defaults.",
                 cfg_file
-            );
+            ));
 
             Self::default()
         };
 
-        let mut level = config.logging().as_str();
+        let mut level = config.logging();
 
         if !LOG_LEVELS.contains(&level) {
             bail!("Invalid default log level: {}", level);
@@ -163,8 +176,8 @@ pub trait AppConfig: Sized + Serialize + DeserializeOwned + Debug + Default {
         println!();
 
         builder.format_timestamp_millis();
-        
-        let mut per_mod = vec![];        
+
+        let mut per_mod = vec![];
         if let Some(mod_levels) = config.logging_mod_levels() {
             for (module, lvl) in mod_levels {
                 per_mod.push((module, log::LevelFilter::from_str(lvl)?));
@@ -187,11 +200,11 @@ pub trait AppConfig: Sized + Serialize + DeserializeOwned + Debug + Default {
                         continue 'sup;
                     }
                 }
-                
+
                 builder.filter_module(lib, sup_lvl);
             }
         }
-        
+
         for (module, lvl) in per_mod.into_iter() {
             builder.filter_module(module, lvl);
         }