How to create instances from Array values

Question

I'm quite new to rust and used to write code in other languages like JavaScript. My project is to code a program to control a cc2500 chip from my raspberry pi via rppal crate in Rust. So far it works but I'm searching for the right way.

Given: I have a list of unsigned 8bit integers and need a list of Segments with delay 20.

In JavaScript I would do it like this

let bytes = [0x7F, 0x55, ...]

let segments = bytes.map(byte => {
    let segment = Segment.with_write([byte]);
    segment.set_delay(20);
    return segment;
});

this.spi.transfer_segments(segments);

In rust I tried it like this

let bytes = vec![0x7F, 0x55, ...];

let mut segments:Vec<Segment> = vec![];
for (i, byte) in bytes.iter().enumerate() {
    let buffer = [byte.clone()];
    segments[i] = Segment::with_write(&buffer);
    segments[i].set_delay(20);
}

let written = self.spi.transfer_segments(&segments)
    .expect("Could not write to SPI bus");

But I always struggle with the ownership rules. How would you do this or what is the best practice?

mcarton · Accepted Answer · 2019-09-02 22:20:23Z

4

Since all of your slices happen to be unary, you can use std::slice::from_ref to create them, pointing to the bytes from your bytes vector:

let bytes = vec![0x7F, 0x55, ...];

let segments = bytes.iter().map(|byte| {
    let buffer = std::slice::from_ref(byte);
    let mut segment = Segment::with_write(buffer);
    segment.set_delay(20);
    segment
});

let segments: Vec<_> = segments.collect().

let written = self.spi.transfer_segments(&segments)
    .expect("Could not write to SPI bus");

answered Sep 2, 2019 at 22:20

mcarton

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