Add --justfile and --working-directory flags

notes

@@ -14,6 +14,11 @@ notes
   - just ../foo  # ../justfile:foo
   - just xyz/foo # xyz/justfile:foo
   - just xyz/    # xyz/justfile:DEFAULT
+- assignment
+  . export environment variables
+  . no barewords
+- indentation is line continuation
+- static errors when variables are missing {{}}, even if recipe isn't run
 
 - change name back to 'just'
   . suggest j as alias
@@ -35,6 +40,7 @@ notes
   . habit of using clever commands and writing little scripts
   . very low friction to write a script (no new file, chmod, add to rcs)
   . make list of contributors, include travis
+  . alias .j='just -j ~/.justfile -d ~'
 - vim and emacs syntax hilighting (use makefile syntax hilighting for now)
 - split up code into modules for easier reading
   . parsing
@@ -48,11 +54,6 @@ notes
   . r/rust
 
 later:
-- indentation is line continuation
-- assignment
-  . export environment variables
-  . no barewords
-- static errors when variables are missing {{}}, even if recipe isn't run
 - preludes:
   may be nice to allow all recipes in a given langauge to share
   functions, variables, etc. could have a "prelude" recipe
@@ -60,8 +61,5 @@ later:
 - windows support: currently calling 'sh', which won't work on windows
   the answer will probably be to write a 'sh' clone and to only
   call binaries from cargo
-- allow specifying justfile on command line with --justfile/-j
-  and dir with --directory/-d, so i can do:
-  alias .j='just -j ~/.justfile -d ~'
 - run recipes asyncronously
 - lint with clippy once it runs on stable

src/app.rs

@@ -32,12 +32,42 @@ pub fn app() {
          .short("s")
          .long("show")
          .takes_value(true)
-         .help("Show information about a recipe"))
+         .value_name("recipe")
+         .help("Show information about <recipe>"))
+    .arg(Arg::with_name("working-directory")
+         .long("working-directory")
+         .takes_value(true)
+         .help("Use <working-directory> as working directory. --justfile must also be set"))
+    .arg(Arg::with_name("justfile")
+         .long("justfile")
+         .takes_value(true)
+         .help("Use <justfile> as justfile. --working-directory must also be set"))
     .arg(Arg::with_name("recipe")
          .multiple(true)
          .help("recipe(s) to run, defaults to the first recipe in the justfile"))
     .get_matches();
 
+  // it is not obvious to me what we should do if only one of --justfile and
+  // --working-directory are passed. refuse to run in that case to avoid
+  // suprises.
+  if matches.is_present("justfile") ^ matches.is_present("working-directory") {
+    die!("--justfile and --working-directory may only be used together");
+  }
+
+  let justfile_option = matches.value_of("justfile");
+  let working_directory_option = matches.value_of("working-directory");
+
+  let text;
+  if let (Some(file), Some(directory)) = (justfile_option, working_directory_option) {
+    text = fs::File::open(file)
+      .unwrap_or_else(|error| die!("Error opening justfile: {}", error))
+      .slurp()
+      .unwrap_or_else(|error| die!("Error reading justfile: {}", error));
+
+    if let Err(error) = env::set_current_dir(directory) {
+      die!("Error changing directory to {}: {}", directory, error);
+    }
+  } else {
     loop {
       match fs::metadata("justfile") {
         Ok(metadata) => if metadata.is_file() { break; },
@@ -58,10 +88,11 @@ pub fn app() {
       }
     }
 
-  let text = fs::File::open("justfile")
+    text = fs::File::open("justfile")
       .unwrap_or_else(|error| die!("Error opening justfile: {}", error))
       .slurp()
       .unwrap_or_else(|error| die!("Error reading justfile: {}", error));
+  }
 
   let justfile = super::parse(&text).unwrap_or_else(|error| die!("{}", error));