Add PathBuf to clap_generate::generate_to

clap_generate/src/lib.rs

@@ -33,6 +33,7 @@ mod shell;
 
 use std::ffi::OsString;
 use std::fs::File;
+use std::io::Error;
 use std::io::Write;
 use std::path::PathBuf;
 
@@ -83,7 +84,7 @@ pub use shell::Shell;
 /// mod cli;
 ///
 /// fn main() {
-///     let m = cli::build_cli().get_matches();
+///     let _m = cli::build_cli().get_matches();
 ///
 ///     // normal logic continues...
 /// }
@@ -95,29 +96,39 @@ pub use shell::Shell;
 /// # Cargo.toml
 /// build = "build.rs"
 ///
+/// [dependencies]
+/// clap = "*"
+///
 /// [build-dependencies]
 /// clap = "*"
+/// clap_generate = "*"
 /// ```
 ///
 /// Next, we place a `build.rs` in our project root.
 ///
 /// ```ignore
 /// use clap_generate::{generate_to, generators::Bash};
+/// use std::env;
+/// use std::io::Error;
 ///
 /// include!("src/cli.rs");
 ///
-/// fn main() {
+/// fn main() -> Result<(), Error> {
 ///     let outdir = match env::var_os("OUT_DIR") {
-///         None => return,
+///         None => return Ok(()),
 ///         Some(outdir) => outdir,
 ///     };
 ///
 ///     let mut app = build_cli();
-///     generate_to::<Bash, _, _>(
+///     let path = generate_to::<Bash, _, _>(
-///         &mut app,     // We need to specify what generator to use
+///         &mut app, // We need to specify what generator to use
-///         "myapp",      // We need to specify the bin name manually
+///         "myapp",  // We need to specify the bin name manually
-///         outdir,       // We need to specify where to write to
+///         outdir,   // We need to specify where to write to
-///     );
+///     )?;
+///
+///     println!("cargo:warning=completion file is generated: {:?}", path);
+///
+///     Ok(())
 /// }
 /// ```
 ///
@@ -127,21 +138,22 @@ pub use shell::Shell;
 ///
 /// **NOTE:** Please look at the individual [generators]
 /// to see the name of the files generated.
-pub fn generate_to<G, S, T>(app: &mut clap::App, bin_name: S, out_dir: T)
+pub fn generate_to<G, S, T>(app: &mut clap::App, bin_name: S, out_dir: T) -> Result<PathBuf, Error>
 where
     G: Generator,
     S: Into<String>,
     T: Into<OsString>,
 {
+    app.set_bin_name(bin_name);
+
     let out_dir = PathBuf::from(out_dir.into());
     let file_name = G::file_name(app.get_bin_name().unwrap());
 
-    let mut file = match File::create(out_dir.join(file_name)) {
+    let path = out_dir.join(file_name);
-        Err(why) => panic!("couldn't create completion file: {}", why),
+    let mut file = File::create(&path)?;
-        Ok(file) => file,
-    };
 
-    generate::<G, S>(app, bin_name, &mut file)
+    _generate::<G, S>(app, &mut file);
+    Ok(path)
 }
 
 /// Generate a completions file for a specified shell at runtime.
@@ -185,7 +197,14 @@ where
     S: Into<String>,
 {
     app.set_bin_name(bin_name);
+    _generate::<G, S>(app, buf)
+}
 
+fn _generate<G, S>(app: &mut clap::App, buf: &mut dyn Write)
+where
+    G: Generator,
+    S: Into<String>,
+{
     // TODO: All the subcommands need to be built instead of just the top one
     app._build();
     app._build_bin_names();