feat(cli): Add init/init_with_config methods to CLI apps

src/cli.rs

@@ -7,6 +7,9 @@ use thiserror::Error;
 
 use crate::config;
 
+// Exit codes as defined in sysexits.h.
+pub const CONFIGURATION_ERROR_EXIT_CODE: i32 = 78;
+
 #[derive(Error, Debug)]
 pub enum CliError {
     #[error(transparent)]
@@ -36,6 +39,18 @@ pub trait AppOpts: Parser {
         result
     }
 
+    fn init() -> Self {
+        match Self::try_init() {
+            Ok(args) => args,
+            Err(CliError::ArgParse(err)) => err.exit(),
+            Err(CliError::Config(err)) => {
+                log::error!("{}", err);
+
+                safe_exit(CONFIGURATION_ERROR_EXIT_CODE);
+            },
+        }
+    }
+
     fn get_log_level_filter(&self) -> Option<LevelFilter> {
         None
     }
@@ -57,6 +72,18 @@ pub trait ConfigurableAppOpts<C: DeserializeOwned + Default + Serialize>: AppOpt
         Ok((opts, conf))
     }
 
+    fn init_with_config() -> (Self, C) {
+        match Self::try_init_with_config() {
+            Ok(args_and_config) => args_and_config,
+            Err(CliError::ArgParse(err)) => err.exit(),
+            Err(CliError::Config(err)) => {
+                log::error!("{}", err);
+
+                safe_exit(CONFIGURATION_ERROR_EXIT_CODE);
+            },
+        }
+    }
+
     fn get_additional_config_paths(&self) -> Vec<PathBuf>;
 }
 
@@ -102,3 +129,15 @@ pub fn get_log_level_filter_from_verbosity(verbosity: u8) -> Option<log::LevelFi
         _ => None,
     }
 }
+
+/// Flushes stdout/stderr and terminates the current process.
+/// 
+/// This is used internally in the library to handle non-critical CLI errors.
+pub fn safe_exit(code: i32) -> ! {
+    use std::io::Write;
+
+    let _ = std::io::stdout().lock().flush();
+    let _ = std::io::stderr().lock().flush();
+
+    std::process::exit(code)
+}
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