Exit Code Control
Managing program exit codes via the resource system
Providing the shell with a correct exit code when a program terminates is a basic CLI convention. Mingling offers a ready-to-use `ExitCodeSetup` that, together with the `ResExitCode` resource, makes exit code control incredibly simple.
## Enabling ExitCodeSetup
```rust
@@@use mingling::prelude::*;
@@@use mingling::setup::ExitCodeSetup;
fn main() {
let mut program = ThisProgram::new();
program.with_setup(ExitCodeSetup::default());
@@@ program.exec_and_exit();
}
```
`ExitCodeSetup` does two things:
1. Registers the `ResExitCode` resource (default value `0`)
2. Registers a `finish` hook that reads the value of `ResExitCode` as the final exit code before the program exits
## Modifying the Exit Code
In a Chain or Renderer, inject `ResExitCode` to modify the exit code:
```rust
@@@use mingling::res::ResExitCode;
@@@use mingling::setup::ExitCodeSetup;
@@@pack!(EntryCheck = Vec);
#[chain]
fn handle_check(_args: EntryCheck, ec: &mut ResExitCode) {
// Modify exit code when check fails
ec.exit_code = 1;
}
```
> [!TIP]
> `ResExitCode` is simply `struct ResExitCode { pub exit_code: i32 }`. Inject `&mut ResExitCode` and modify the field directly.
## Three Execution Modes of `Program`
`Program` provides three execution modes (excluding `exec_repl` under the `repl` feature):
| Mode | Behavior |
| ------------------------------- | ----------------------------------------------------------------------------------------- |
| `program.exec_and_exit()` | Executes and terminates the process directly with the exit code |
| `program.exec()` | Executes and returns an `i32` exit code, letting the caller decide handling |
| `program.exec_without_render()` | Returns `Result`, with internal `exit_code` accessible |
```rust
@@@use mingling::setup::ExitCodeSetup;
fn main() {
let mut program = ThisProgram::new();
program.with_setup(ExitCodeSetup::default());
// Get exit code and handle it yourself
let exit_code = program.exec();
std::process::exit(exit_code);
}
@@@gen_program!();
```
Written by @Weicao-CatilGrass