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Using Configuration Files ​

Often programs require information that would typically be stored in a configuration file, such as hardware pins, Wi-Fi network SSIDs, passwords, URLs, etc.

Unfortunately, configurations cannot be saved as a .json or .yaml file since the information needs to be embedded in the code when compiling to WebAssembly. If this sounds weird, remember that WebAssembly has no standard way of reading from files.

Instead of a data file, you can save the configuration in a separate program file.

Program ​

Say, we want to move the pin number for the LED from the previous examples, to a configuration file. The contents of the config file looks as follows:

ts
export const LED: u32 = 26;
rust
pub static LED: u32 = 26;

Then, we can import the configuration in our program as a normal dependency.

ts
import {pinMode, PinMode} from "as-warduino/assembly";
import * as config from "./config";

export function main(): void {
    let led = config.LED;
    pinMode(led, PinMode.OUTPUT);
}
rust
use warduino::{pin_mode, PinMode};

mod config;

#[no_mangle]
pub fn main() {
    let led: u32 = config::LED;
    pin_mode(led, PinMode::OUTPUT);
}

In the next examples, we will move sensitive information such as Wi-Fi passwords to configuration files.