env_struct

This crate is very opinionated env management crate for building good env management habits and avoiding global variables if possible, and having sane defaults.

Can still be used with lazy_init to load the struct as a global static. But that isn't baked into this. In future one should be able to use the new lazy once_cell in API in rust_std once it gets stablized.

A quick example of usage looks like,

use env_struct::env_struct;

env_struct! {
    #[derive(Debug)] // (Optional) Not needed, just to
    //  show that we keep derive & other macros intact
    pub struct ConfigEnvWithDefault { // vis modifiers work too
        // Will use `CONFIG_PATH`
        pub config_path = "/path/to/config.toml", 
        // Will use `RESULT_PATH`
        pub result_path = "/path/to/result.toml", 
    } 
}

pub fn main() {
    let env_config = ConfigEnvWithDefault::load_from_env();

    if let Some(s) = entry_point(&env_config) {
        eprintln!("Program exited successfullly!");
        post_run_operations(&env_config);
        // we don't care if the post run operations
        // such as cleanup or such fail.
    } else {
        eprintln!("Program exit status invalid!");
        std::process::exit(1);
    }
}

Or for config where you want to ensure you have env setup,

use env_struct::env_struct;

env_struct! {
    #[derive(Debug)] // (Optional) Not needed, just to
    //  show that we keep derive & other macros intact
    pub struct RequiredConfigEnv { // vis modifiers work too
        // Will use `CONFIG_PATH`
        pub config_path, 
        // Will use `RESULT_PATH`
        pub result_path,
    }
}


pub fn main() {
    // Result<RequiredConfigEnv, String>
    // Error: String above will name the var that couldn't be read.
    let env_config = RequiredConfigEnv::try_load_from_env().unwrap();

    if let Some(s) = entry_point(&env_config) {
        eprintln!("Program exited successfullly!");
        post_run_operations(&env_config);
        // we don't care if the post run operations
        // such as cleanup or such fail.
    } else {
        eprintln!("Program exit status invalid!");
        std::process::exit(1);
    }
}

My Opinions

Environment variable structs are a better for env management.

As then you can ensure the nature of sync on top of env on your own, and don't have to pay the cost of Atomics without needing to use them in your single threaded application.

Also this works better when your system already has a context provider, for dependency injection, for instance, in a GUI application.

And, defaults should always exist if only to inform the user of the lack of configuration.

Roadmap

• Support custom aliases for env_var key.

Dependencies

None, and the entire project is less than 100 lines of code.

Contribution

Open to accept PR to fix any bugs or add more quality of life features, just try to follow the "keep it minimal" philosophy.

I don't want to ship features that aren't directly relevant or would be soon implemented in rust std and are provided by most other crates.

This is supposed to be a very very minimal project.