src: use clap's default value mechanism

src/main.rs

@@ -2,10 +2,7 @@ use std::{process, thread, time::Duration};
 
 use anyhow::{anyhow, Context};
 use clap::Parser;
-use dim_screen::{
-    dim::DimData,
-    opts::{DimOpts, DEFAULT_ALPHA, DEFAULT_DURATION},
-};
+use dim_screen::{dim::DimData, opts::DimOpts};
 use smithay_client_toolkit::{
     compositor::CompositorState,
     reexports::client::{globals::registry_queue_init, Connection},
@@ -30,10 +27,9 @@ fn main() -> anyhow::Result<()> {
     let compositor = CompositorState::bind(&globals, &qh).context("Compositor not available")?;
     let layer_shell = LayerShell::bind(&globals, &qh).context("Layer shell failed?")?;
 
-    let alpha = args.alpha.unwrap_or(DEFAULT_ALPHA);
-    let mut data = DimData::new(compositor, &globals, &qh, layer_shell, alpha);
+    let alpha = args.alpha;
+    let duration = args.duration;
 
-    let duration = args.duration.unwrap_or(DEFAULT_DURATION);
     // A duration of 0 is considered as infinite, not starting the timer:
     if duration > 0 {
         thread::spawn(move || {
@@ -42,6 +38,7 @@ fn main() -> anyhow::Result<()> {
         });
     }
 
+    let mut data = DimData::new(compositor, &globals, &qh, layer_shell, alpha);
     while !data.should_exit() {
         event_queue
             .blocking_dispatch(&mut data)

src/opts.rs

@@ -8,27 +8,27 @@ use std::{
 use clap::{CommandFactory, Parser, ValueEnum};
 use clap_complete::{generate_to, Shell};
 
-/// Default duration in seconds
-pub const DEFAULT_DURATION: u64 = 30;
-
-pub const DEFAULT_ALPHA: f32 = 0.5;
+const DEFAULT_DURATION: u64 = 30;
+const DEFAULT_ALPHA: f32 = 0.5;
 
 #[derive(Debug, Parser)]
 #[command(author, version, about)]
 pub struct DimOpts {
     #[arg(
         short,
         long,
-        help = format!("Duration in seconds, 0 is infinite, default is {DEFAULT_DURATION}")
+        default_value_t = DEFAULT_DURATION,
+        help = "Duration in seconds, 0 is infinite"
     )]
-    pub duration: Option<u64>,
+    pub duration: u64,
 
     #[arg(
         short,
         long,
-        help = format!("0.0 is transparent, 1.0 is opaque, default is {DEFAULT_ALPHA}")
+        default_value_t = DEFAULT_ALPHA,
+        help = "0.0 is transparent, 1.0 is opaque"
     )]
-    pub alpha: Option<f32>,
+    pub alpha: f32,
 
     #[arg(long, value_name = "PATH", help = "Generate completions at given path")]
     pub gen_completions: Option<PathBuf>,