chore!: simplify ExitCodeSetup to non-generic unit struct

2 files changed, 40 insertions, 24 deletions

diff --git a/mingling/src/example_docs.rs b/mingling/src/example_docs.rs
index c9955b5..055615d 100644
--- a/mingling/src/example_docs.rs
+++ b/mingling/src/example_docs.rs
@@ -1318,7 +1318,7 @@ pub mod example_error_handling {}
 ///
 ///     // --------- IMPORTANT ---------
 ///     // Register `ExitCodeSetup` for the program to enable exit codes
-///     program.with_setup(ExitCodeSetup::default());
+///     program.with_setup(ExitCodeSetup);
 ///     // --------- IMPORTANT ---------
 ///
 ///     program.exec_and_exit();
diff --git a/mingling/src/setups/exit_code.rs b/mingling/src/setups/exit_code.rs
index e31e511..0558892 100644
--- a/mingling/src/setups/exit_code.rs
+++ b/mingling/src/setups/exit_code.rs
@@ -1,8 +1,5 @@
-// Doc Not Optimize
-use std::marker::PhantomData;
-
 use mingling_core::{
-    ProgramCollect,
+    Program, ProgramCollect,
     hook::{ProgramControlUnit, ProgramControls, ProgramHook},
     setup::ProgramSetup,
     this,
@@ -10,30 +7,49 @@ use mingling_core::{
 
 use crate::res::ResExitCode;
 
-/// Provides the ability to control the program's exit code, which is returned when the program ends.
+/// `ExitCodeSetup` — Setup for controlling the program's exit code
 ///
-/// - Use `mingling::update_exit_code` to update the exit code.
-/// - Use `mingling::current_exit_code` to query the current exit code.
-pub struct ExitCodeSetup<C> {
-    _collect: PhantomData<C>,
-}
-
-impl<C> Default for ExitCodeSetup<C>
-where
-    C: ProgramCollect<Enum = C> + 'static,
-{
-    fn default() -> Self {
-        Self {
-            _collect: PhantomData,
-        }
-    }
-}
+/// This Setup registers an [`ResExitCode`] resource that tracks the desired exit
+/// code for the program. When the program finishes, a hook reads this resource
+/// and overrides the program's exit code if it has been modified from its
+/// default value of `0`.
+///
+/// # Usage
+///
+/// This Setup can be registered using the
+/// [`Program`](https://docs.rs/mingling/latest/mingling/struct.Program.html)
+/// `with_setup` method, for example:
+///
+/// ```rust
+/// # use mingling::MockProgramCollect as ThisProgram;
+/// use mingling::Program;
+/// use mingling::setup::ExitCodeSetup;
+///
+/// let mut program = Program::<ThisProgram>::new();
+/// program.with_setup(ExitCodeSetup);
+/// ```
+///
+/// # Behavior
+///
+/// - Registers an [`ResExitCode`] resource initialised to `0`.
+/// - Installs a program-finish hook that:
+///   - Reads the current [`ResExitCode`] value.
+///   - Overrides the program's exit code with that value if it is non-zero.
+///   - Leaves the exit code untouched if the resource still holds its default
+///     value of `0`.
+///
+/// # Notes
+///
+/// - Use [`update_exit_code`](crate::update_exit_code) to set a custom exit code
+///   during program execution.
+/// - Use [`current_exit_code`](crate::current_exit_code) to query the current value.
+pub struct ExitCodeSetup;
 
-impl<C> ProgramSetup<C> for ExitCodeSetup<C>
+impl<C> ProgramSetup<C> for ExitCodeSetup
 where
     C: ProgramCollect<Enum = C> + 'static,
 {
-    fn setup(self, program: &mut crate::Program<C>) {
+    fn setup(self, program: &mut Program<C>) {
         // Insert resource
         program.with_resource(ResExitCode { exit_code: 0 });