El Roi Project

El Roi is a Rust library that simplifies reading user input from the command line. It provides ergonomic functions for reading strings, integers, floats, booleans, characters, and vectors of these types, with both prompted (prompt_*) and unprompted APIs for stream-style input. The crate is designed for usability, clarity, and testability.

Purpose

El Roi abstracts away the repetitive patterns of reading and parsing user input, allowing developers to easily and safely gather data from users in CLI applications.

Features

Prompted and unprompted input variants for each supported type
Read integers (i32), floating-point numbers (f64), booleans, characters, and vectors of these types
Consistent, easy-to-use API for all supported types
Testable design: parsing logic is separated for easy unit testing
Invalid inputs print an error with an example and re-prompt (prompted APIs)

Installation

Add El Roi as a dependency in your project's Cargo.toml:

el_roi = "0.2.0"

Or, if using a local path during development:

el_roi = { path = "../el_roi" }

Usage

Import and use the utility functions in your Rust code. Prompted functions use prompt_* names (e.g., prompt_int) while unprompted functions keep the original names (e.g., read_int). This makes it easy to build both question/answer flows and constant input streams like CLI games.

Basic Example

use el_roi::{
    prompt_bool, prompt_char, prompt_float, prompt_float_vec, prompt_int, prompt_int_vec,
    prompt_string, prompt_string_vec,
};

fn main() {
    let name = prompt_string("Enter your name");
    let age = prompt_int("Enter your age");
    let pi = prompt_float("Enter the value of pi");
    let likes_rust = prompt_bool("Do you like Rust? (true/false)");
    let initial = prompt_char("Enter the first letter of your name");
    let numbers = prompt_int_vec("Enter some numbers separated by spaces");
    let floats = prompt_float_vec("Enter some floats separated by spaces");
    let words = prompt_string_vec("Enter some words separated by spaces");
    println!("Hello, {}! Age: {} Pi: {} Likes Rust: {} Initial: {} Numbers: {:?} Floats: {:?} Words: {:?}",
        name, age, pi, likes_rust, initial, numbers, floats, words);
}

Function Reference

Prompted reads will re-prompt on invalid input and print an example of valid input.

prompt_string(prompt: &str) -> String — Read a string with a prompt
prompt_int(prompt: &str) -> i32 — Read an integer with a prompt
prompt_float(prompt: &str) -> f64 — Read a floating-point number with a prompt
prompt_bool(prompt: &str) -> bool — Read a boolean with a prompt (true/false, yes/no, 1/0)
prompt_char(prompt: &str) -> char — Read a single character with a prompt
prompt_int_vec(prompt: &str) -> Vec<i32> — Read a vector of integers with a prompt (space-separated)
prompt_float_vec(prompt: &str) -> Vec<f64> — Read a vector of floats with a prompt (space-separated)
prompt_string_vec(prompt: &str) -> Vec<String> — Read a vector of strings with a prompt (space-separated)
read_string() -> String — Read a string without a prompt (stream-friendly)
read_int() -> i32 — Read an integer without a prompt
read_float() -> f64 — Read a floating-point number without a prompt
read_bool() -> bool — Read a boolean without a prompt
read_char() -> char — Read a single character without a prompt
read_int_vec() -> Vec<i32> — Read a vector of integers without a prompt (space-separated)
read_float_vec() -> Vec<f64> — Read a vector of floats without a prompt (space-separated)
read_string_vec() -> Vec<String> — Read a vector of strings without a prompt (space-separated)

Example: Reading Multiple Types

use el_roi::{prompt_bool, prompt_int, prompt_string};

fn main() {
    let username = prompt_string("Username");
    let age = prompt_int("Age");
    let is_admin = prompt_bool("Are you an admin? (yes/no)");
    println!("User: {}, Age: {}, Admin: {}", username, age, is_admin);
}

Testing

All parsing logic is separated into private helper functions, making it easy to test with in-memory buffers. See the crate's tests for examples.

License

This project is licensed under the MIT License. See the LICENSE file for details.

el_roi 0.2.0