Refactor of parsing arguments into correct types

[leggettc18]

In GitLab by @leggettc18 on Sep 27, 2018, 18:14

/u/usernamedottxt on Reddit said

This:

let goal = if goal.is_some() {
        Some(goal.unwrap().parse::<f64>()?)
    } else {
        None
    };

Can be written as:

let goal = goal.map_or(None, |x| x.parse::<f64>())?;

https://www.reddit.com/r/rust/comments/9jdjpc/my_new_project_in_rust_open_to_critiques_and/e6qno3f

[leggettc18]

In GitLab by @leggettc18 on Sep 27, 2018, 18:23

changed the description

[leggettc18]

In GitLab by @leggettc18 on Sep 27, 2018, 22:54

changed the description

[leggettc18]

In GitLab by @leggettc18 on Sep 28, 2018, 05:50

Upon further investigation, I am not sure this is exactly correct. For a few reasons

1. The map_or function returns a value of the type of the default value provided, and the mapping function
   should also return a value of that type. However, in the example above, it returns either a None or a
   Result<f64, std::num::ParseFloatError>. The ? then unwraps the Result into just f64 (or returns any parsing error to the calling function). The variable I am assigning the value to is intended to be of type Some(f64)
2. With the example exactly as it was, I got the error the trait bound std::option::NoneError: std::error::Error is not satisfied. However, it appears that NoneError is an experimental nightly-only API.

At the moment I do not know how to solve these errors, so I have left the functions as they are. I did change them so that they remove the decimal points and save integers instead of floats in !2. I will leave the issue open for now.

[leggettc18]

In GitLab by @leggettc18 on Oct 2, 2018, 13:14

mentioned in commit 38da5f2

[leggettc18]

In GitLab by @leggettc18 on Oct 2, 2018, 13:16

mentioned in merge request !6

[leggettc18]

In GitLab by @leggettc18 on Oct 2, 2018, 13:17

mentioned in commit 132a59d

[leggettc18]

In GitLab by @leggettc18 on Oct 2, 2018, 13:17

closed via merge request !6