Moving Error Handling to Error Chains

Moving Errors To Error Chain

After doing some research on different ways of handling errors, and the chaining of errors from different modules, I found the error-chain library. This allows for the use of a standard way of creating the file for your module. The rust-lang book entry on error handling has a good entry on error handling and why each step is important. I reccomend going through this tutorial.

However, error-chain more or less takes the canonical methodology, which has a lot of boiler plate, this allows you to create Error, Result, and ErrorKind types which can be properly Boxed and wrapped using the From::from trait so that all Error types appear to be the same trait object. The most compelling feature of error-chain for me is that it can also convert Error types or enums from other libraries into part of your 'error chain'.

For example:

use sysfs_pwm;

// Define the errors for this crate.
error_chain! {
    types {
        Error, ErrorKind, ResultExt, Result;

    links {}

    foreign_links {

    errors {
        NotEnoughLiquid(level: f64) {
            description("There is not enough liquid in the current dispense")
            display("There is currently {} mL left in the dispenser, this is not enough.", level)

Simple Dispenser Implementation for Adafruit Peristaltic Pump

Currently I am making an assumption that the peristaltic pump will respond linearly to the duty cycle with 100% duty cycle corresponding to the max flow rate and 50% corresponding to 50% of the max flow rate. This is an over simplification, but will provide sufficient results for the time being.s

Starting to Design the Mixer Struct

The Mixers are essentially a HashMap of String's mapping to Dispensers. Because the Dispensers are a trait object they must be Box<Dispenser>s. The plan is to implement the following:

  • clear
  • add
  • remove
  • get
  • iter
  • make_recipe
  • status