other/dummy: add sample to handle options

Author: Mingshen Sun

libmesabox/src/other/dummy.rs

@@ -13,13 +13,35 @@ use {UtilSetup, ArgsIter, Result, UtilRead, UtilWrite};
 const NAME: &str = "dummy";
 pub const DESCRIPTION: &str = "A dummy utility to demonstrate the framework";
 
+type DummyResult<T> = ::std::result::Result<T, DummyError>;
+
 #[derive(Fail, Debug)]
 enum DummyError {
-    #[fail(display = "something wrong")]
+    #[fail(display = "oh no, something wrong")]
     SomethingWrong
 }
 
-type DummyResult<T> = ::std::result::Result<T, DummyError>;
+struct DummyOptions {
+    verbose: bool
+}
+
+impl DummyOptions {
+    fn from_matches(matches: &ArgMatches) -> Self {
+        let mut options = Self::default();
+
+        options.verbose = matches.is_present("verbose");
+
+        options
+    }
+}
+
+impl Default for DummyOptions {
+    fn default() -> Self {
+        Self {
+            verbose: false
+        }
+    }
+}
 
 struct Dummyer<O>
 where
@@ -36,18 +58,23 @@ where
         Dummyer { output }
     }
 
-    fn dummy(&mut self) -> DummyResult<()> {
-        writeln!(self.output, "write something to the output");
+    fn dummy(&mut self, options: &DummyOptions) -> DummyResult<()> {
+        if options.verbose {
+            writeln!(self.output, "Hello, world! This is a dummy utility. I am very verbose :)");
+            return Err(DummyError::SomethingWrong)?
+        } else {
+            writeln!(self.output, "Hello, world!");
+        }
         Ok(())
     }
 }
 
 fn create_app() -> App<'static, 'static> {
     util_app!(NAME)
-        .arg(Arg::with_name("about")
-                .short("a")
-                .long("about")
-                .help("show about"))
+        .arg(Arg::with_name("verbose")
+                .short("v")
+                .long("verbose")
+                .help("Say hello in verbose mode"))
 }
 
 pub fn execute<S, T>(setup: &mut S, args: T) -> Result<()>
@@ -57,11 +84,12 @@ where
 {
     let app = create_app();
     let matches = app.get_matches_from_safe(args)?;
+    let options = DummyOptions::from_matches(&matches);
 
     let output = setup.output();
     let mut output = output.lock()?;
 
     let mut dummyer = Dummyer::new(output);
-    dummyer.dummy()?;
+    dummyer.dummy(&options)?;
     Ok(())
 }