Read Input

A simple tool that asks for data until the data is valid.

Help

If you run into any issues or need help with using read_input in your project please email incoming+efunb/read_input@incoming.gitlab.com

Why you need it

When writing simple programs you will often need to take input from the user. If the user inputs invalid information the program needs to ask them again. Having to make this loop distracts from the useful logic in your program.

read_input attempts to make it easy to get input from the user without having to think about converting types.

How to use

Add

read_input = "0.3"

to your cargo.toml under [dependencies] and add

extern crate read_input;

use read_input::*;

to your main file.

You can get input with.

let input = input_new::<Type>().get();

Where Type is the type you want. Currently the you can use all types that implement std::str::FromStr. This currently includes the standard library types isize, usize, i8, u8, i16, u16, f32, i32, u32, f64, i64, u64, i128, u128, char, Ipv4Addr, Ipv6Addr, SocketAddrV4, SocketAddrV6 and String. Many crates also implement std::str::FromStr for their types.

For example, if you want a valid unsigned 32bit value you could write.

let input = input_new::<u32>().get();

Often rust can work out the type so you can skip explicitly stating the type.

let input = input_new().get();

You can also add your own checks to ensure the value meets your criteria. If you want a integer between 4 and 9 you could write.

let input = input_new().test(&|x| 4 < *x && *x < 9, None).get()

In the same style you can specify custom error messages, custom test errors and multiple tests. If you want a value between 4 and 9 that is not 6 you could write.

let input = input_new()
    .msg("Please input a number between 4 and 9 that is not 6: ")
    .test(&|x| 4 < *x && *x < 9, None)
    .test(
        &|x| *x != 6,
        Some("That value is 6! I dont want 6. Please try again")
    )
    .err("That does not look like a number between 4 and 9. Please try again")
    .get()

Default values and custom messages are also supported. If the user presses enter before typing anything the program could return a default value. Custom messages are written on the same line as input.

let input = input_new().msg("Please input pi: ").default(3.141).get();

Shortcut functions

Using input_new().get() can be a little verbose in simple situations. The functions simple_input() and valid_input() can make things simpler.

simple_input() is the same as input_new().get().

valid_input(&|x| 4 < *x && *x < 9) is the same as input_new().test(&|x| 4 < *x && *x < 9, None).get().

How to use with custom type

To use read_input with a custom type you need to implement std::str::FromStr for that type. Documentation

More complex examples

• simple_guessing_game. The guessing game form the rust book made to use read_input.

• guessing_game. The guessing game form the rust book made to use read_input + some extra features.

• how_long_until. Program that uses read_input with the crate chrono.

Docs

API Documentation

Warning

If you are viewing this from GitHub then this is a read only copy. Please contribute to the GitLab copy here.