refactor: use env feature of cargo

Cargo.toml

@@ -13,7 +13,7 @@ license = "MIT"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-clap = { version = "4.5.26", features = ["derive"] }
+clap = { version = "4.5.26", features = ["derive", "env"] }
 fit_file = "0.6.0"
 geo-types = "0.7.14"
 gpx = "0.10.0"

src/elevation.rs

@@ -22,21 +22,13 @@ pub fn needed_tile_coords(wps: &[Waypoint]) -> Vec<(i32, i32)> {
 // TODO: docs
 pub fn read_needed_tiles(
     needs: &[(i32, i32)],
-    elev_data_dir: Option<impl AsRef<Path>>,
+    elev_data_dir: impl AsRef<Path>,
 ) -> Vec<srtm_reader::Tile> {
     if needs.is_empty() {
         return vec![];
     }
+    let elev_data_dir = elev_data_dir.as_ref();
 
-    let elev_data_dir = if let Some(arg_data_dir) = &elev_data_dir {
-        arg_data_dir.as_ref()
-    } else if let Some(env_data_dir) = option_env!("ELEV_DATA_DIR") {
-        Path::new(env_data_dir)
-    } else if let Some(env_data_dir) = option_env!("elev_data_dir") {
-        Path::new(env_data_dir)
-    } else {
-        panic!("no elevation data dir is passed as an arg nor set as an environment variable: ELEV_DATA_DIR");
-    };
     needs
         .par_iter()
         .map(|c| srtm_reader::get_filename(*c))
@@ -79,7 +71,7 @@ pub fn get_all_elev_data<'a>(
 /// use fit2gpx::elevation::*;
 ///
 /// let mut fit = fit2gpx::Fit::from_file("evening walk.gpx").unwrap();
-/// let elev_data_dir = Some("/home/me/Downloads/srtm_data");
+/// let elev_data_dir = "/home/me/Downloads/srtm_data";
 /// let needed_tile_coords = needed_tile_coords(&fit.track_segment.points);
 /// let needed_tiles = read_needed_tiles(&needed_tile_coords, elev_data_dir);
 /// let all_elev_data = get_all_elev_data(&needed_tile_coords, &needed_tiles);

src/lib.rs

@@ -140,7 +140,7 @@ impl Fit {
 
     #[cfg(feature = "elevation")]
     /// add elevation data to the `fit` file, using srtm data from `elev_data_dir`
-    pub fn add_elev(fit: &mut Fit, elev_data_dir: Option<impl AsRef<Path>>) {
+    pub fn add_elev(fit: &mut Fit, elev_data_dir: impl AsRef<Path>) {
         use elevation::*;
         let needed_tile_coords = needed_tile_coords(&fit.track_segment.points);
         let needed_tiles = read_needed_tiles(&needed_tile_coords, elev_data_dir);

src/main.rs

@@ -8,10 +8,10 @@ use std::path::PathBuf;
 struct Args {
     pub files: Vec<PathBuf>,
     #[cfg(feature = "elevation")]
-    #[arg(short = 'd', long)]
-    pub elev_data_dir: Option<PathBuf>,
+    #[arg(short = 'd', long, env)]
+    pub elev_data_dir: PathBuf,
     #[cfg(feature = "elevation")]
-    #[arg(short, long, default_value_t = false)]
+    #[arg(short, long, default_value_t = false, requires = "elev_data_dir")]
     pub add_elevation: bool,
     #[arg(short, long, default_value_t = false)]
     pub overwrite: bool,