_hello-world_

Hello World Example for Package Generation

The _hello-world_ example demonstrates how to generate and compile a fully functional package from an sdf-package.yaml file. The example will utilize regex to look up and convert the word good to great.

Prerequisites

• Install SDF if you haven't already.
• Look at the sdf-package.yaml to see the type and function definitions.

Generate Package Sandbox

Use the generate scaffold to create the package sandbox:

sdf generate

The generator reads the sdf-package.yaml file and creates the following Rust project:

$ tree
.
├── README.MD
├── rust
│   └── hello-world
│       ├── Cargo.toml
│       ├── README.md
│       └── src
│           ├── hello_world.rs
│           └── lib.rs
└── sdf-package.yaml

Each function generates a new file. In this case, we only have one function, which generated the hello_world.rs file.

Add Custom Code

Open the rust/hello-world/src/hello_world.rs file and add the following code:

use std::sync::LazyLock;

use regex::Regex;

static REGEX: LazyLock<Regex> = LazyLock::new(|| Regex::new(r"good").unwrap());

#[sdf(fn_name = "hello-world")]
pub(crate) fn hello_world(input: Good) -> Result<Great> {
    let output = REGEX.replace_all(input.as_str(), "great").to_string();
    Ok(output)
}

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn test_hello_world() {
        let input = "This is good.".to_string();
        let output = hello_world(input);
        assert_eq!(output.unwrap(), "This is great.".to_string());
    }
}

The test we've included is not strictly necessary but a best practice.

We'll also need to update the Cargo.toml file to include the regex dependency.

[dependencies]
...
regex = "1"

Add regex to the end of the file.

Build the Package

To build the code, run:

sdf build

The build command creates a fully functional package that can be imported by other packages or dataflows.

Test the Code with SDF

Inside the sdf-package.yaml directory, run:

sdf test

>> test function hello-world --value "This is good."
This is great.

Test the code with Cargo

You also have the option to test your routines using rust test utilities. Inside the rust/hello-world directory, run the tests using Rust:

cargo test

🎉 Congratulations! You have successfuly built your first package.