Compile and run rust programs without creating separate cargo projects - rust

Question

While going through Rust by Example,
I found myself creating a new cargo project for each program in the tutorial.
This quickly turned cumbersome.
Another strategy I tried was having my working directory structured like this:
src\
guessing_game.rs
main.rs
temp.rs
where main.rs contains
mod guessing_game;
mod temp;
/// Hello
fn main() {
// guessing_game::play();
println!("{}", temp::is_prime(6));
}
and cargo.toml contains
[package]
name = "rust_prog_dump"
version = "0.1.0"
edition = "2018"
# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
[dependencies]
rand = "0.8.4"
I would call the target function in main() and comment out the others.
Do we have an alternative?
I have seen this issue and Jon Cairns' post.
I use Windows, hence that script does not work for me.

Answer 1

Do we have an alternative?
One alternative is to compile by hand using rustc directly, however that is annoying if you want dependencies.
An other alternative is to have multiple binaries in the crate, then you can select the binary to compile (and run) using --bin:
> cargo new multibin
Created binary (application) `multibin` package
> cd multibin
> mkdir src/bin
> echo 'fn main() { println!("test 1"); }' > src/bin/test1.rs
> echo 'fn main() { println!("test 2"); }' > src/bin/test2.rs
> echo 'fn main() { println!("primary"); }' >| src/main.rs
> cargo r
error: `cargo run` could not determine which binary to run. Use the `--bin` option to specify a binary, or the `default-run` manifest key.
available binaries: multibin, test1, test2
> cargo r --bin multibin
Compiling multibin v0.1.0 (/private/tmp/multibin)
Finished dev [unoptimized + debuginfo] target(s) in 0.44s
Running `target/debug/multibin`
primary
> cargo r --bin test1
Compiling multibin v0.1.0 (/private/tmp/multibin)
Finished dev [unoptimized + debuginfo] target(s) in 0.10s
Running `target/debug/test1`
test 1
> cargo r --bin test2
Compiling multibin v0.1.0 (/private/tmp/multibin)
Finished dev [unoptimized + debuginfo] target(s) in 0.10s
Running `target/debug/test2`
test 2
As you can see you can have a src/main.rs which will inherit the crate's name, but usually if you start having multiple binaries you put them all in src/bin.
A third alternative is to use something like cargo-script (by far the most convenient but long unmaintained and IIRC only compatible with edition 2015) or runner or something along those lines (there are probably others).

Answer 2

Masklinn's multiple-binary solution works like a charm (one-click execution) when paired with a good IDE.
With IntelliJ Community Edition + the Rust and TOML plugins
Choose the TOML file when prompted. (Only when importing the project)
Go to Project Settings > Modules. Mark src/bin as a Source folder.
Restart the IDE. You will have Current File as an available run configuration.
With VS Code + the Code Runner extension
Click on the Run|Debug button that appears above fn main(). Note that the regular Run Code shortcut (Ctrl+Alt+N) may not work if you have dependencies.