rclap 0.1.1

rclap is a Rust configuration utility to help to generate the clap structures. The main purpose is to reduce boilerplate code when using clap and expose the configuration requirements as a toml file.
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# rclap

![Rust](https://img.shields.io/badge/rust-stable-brightgreen.svg)
[![Version](https://img.shields.io/crates/v/rclap.svg)](https://crates.io/crates/rclap)
[![Docs.rs](https://docs.rs/rclap/badge.svg)](https://docs.rs/rclap)

> rclap is a configuration helper based on clap. It is designed to expose the requirement as config files, environment variables, and command line arguments with the least amount of boilerplate code.
> Macro clap generator based on toml files

# Usage

## simple toml file

```toml
port = { type = "u16", default = "8080", doc = "Server port number", env = "PORT" }
ip = {  default = "localhost", doc = "connection URL", env = "URL" }
```

Then the config struct can be used by the following code

```rust,compile_fail
use clap::Parser;
use rclap::config;

#[config]
struct MyConfig;
fn main() {
    let config = MyConfig::parse();
    println!("Config: {:#?}", config);
    println!("{}", &config.port);
}
```

The ip and port can be set by environment variables or command line arguments. The default values will be used if neither is set.
Arguments can be set by `--ip` and `--port` command line arguments and the following help message will be generated:

```

Usage: example [OPTIONS]

Options:
      --"ip" <ip>      connection URL [env: URL=] [default: localhost]
      --"port" <port>  Server port number [env: PORT=120] [default: 8080]
  -h, --help           Print help
```

The equivalent for the above code will be generated by the macro:

```rust,compile_fail


   #[derive(Debug, Clone, PartialEq, Default, Parser)]
   pub struct MyConfig {
        ///Server port number
        #[arg(
            id = "port",
            default_value_t = 8080,
            env = "PORT",
            long = stringify!("port")
        )]
        pub port: u16,
        ///connection URL
        #[arg(
            id = "ip",
            default_value = "localhost",
            env = "URL",
            long = stringify!("ip")
        )]
        pub ip: String,
    }

```

The [example folder](./example) contains more working samples.

## settings

| name        | description                                                              |
| ----------- | ------------------------------------------------------------------------ |
| **type**    | if not specified, `String` type will be used                             |
| **env**     | the environment variable name to use                                     |
| **long**    | same as in clap if not specified the id value will be used instead       |
| **short**   | same as in clap                                                          |
| **default** | the default value to use if neither env nor command line argument is set |
| **doc**     | the documentation string to use                                          |

## dependencies

rclap is macro generator based on [clap](https://crates.io/crates/clap) and [toml](https://crates.io/crates/toml).
the clap library is used to parse command line arguments and must be imported

```toml

clap = { version = "4.5", features = ["env", "derive"] }
```