Variable assignment in a match

help
1

Hello,

I'm new to Rust and come from the PHP world so I'm having a bit of a hard time figuring it all out.
I'm trying to do a match on a string (it works) and assign to a variable an object of type termion::color but as I'm changing color it doesn't work...as soon as I do the first assignment, rust expects me to assign the same object to this variable.

    let color_choice = match &*data_color.color { 
        "Red" => color::Red,
        "Blue" => color::Blue,
        "Yellow" => color::Yellow,
        "Green" => color::Green,                 
        _ => color::White,
    };

The error :

27 |       let mut color_choice = match &*data_color.color { 
   |  ____________________________-
28 | |         "Red" => color::Red,
   | |                  ---------- this is found to be of type `Red`
29 | |         "Blue" => color::Blue,
   | |                   ^^^^^^^^^^^ expected struct `Red`, found struct `Blue`
30 | |         "Yellow" => color::Yellow,
31 | |         "Green" => color::Green,                 
32 | |         _ => color::White,
33 | |     };
   | |_____- `match` arms have incompatible types

How can I do this?

Or do you have an easier way to be able to use a different color directly without going through a match?
Here is my fonction :

struct DataColor { 
    color: String,
    bold: bool,
    args: Vec<String>,
}
fn print_with_color(data_color: DataColor) {
    let color_choice = match &*data_color.color { 
        "Red" => color::Red,
        "Blue" => color::Blue,
        "Yellow" => color::Yellow,
        "Green" => color::Green,                 
        _ => color::White,
    };
    for text in &data_color.args {
        if data_color.bold {
            println!("{}{}{}", color::Fg(color_choice), style::Bold, text);
        } else { 
            println!("{}{}", color::Fg(color_choice), text);    
        }
    }
}

As I don't know how I can pass the termion::color object directly to my function (color: String need to be a color::XX), I therefore pass through a string of the type "Red", "Green"... and then via the match I thought of assigning it to a variable the right color.

Thanks in advance and sorry for his amateurish questions.

2

Those colors are structs of differents type. To solve your immediate issue you can wrap them in your own enum :

enum Color {
    Red(termion::color::Red),
    Green(termion::color::Green),
    Blue(termion::color::Blue),
    ...
}

Or Box the values using the Color trait :

let color_choice: Box<dyn color::Color> = match &*data_color.color { 
    "Red" => Box::new(color::Red),
    ...
};
3 Likes
3

Looking at the implementations of the relevant trait, it looks like you could work well with &'static dyn Color in this case.

Try something like

    let color_choice: &dyn Color = match &*data_color.color { 
        "Red" => &color::Red,
        "Blue" => &color::Blue,
        "Yellow" => &color::Yellow,
        "Green" => &color::Green,                 
        _ => &color::White,
    };

(you might need to import that trait, use termion::color::Color;)

2 Likes
4

Thanks you. It's ok now

5

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