Small pattern that made my code much cleaner (lemmy.ca)

submitted 11 months ago by kia@lemmy.ca to c/rust@programming.dev

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This is a really simple silly thing I just realized, but I noticed I have a lot code that looks something like this:

fn foo() -> Result&lt;(), Error> {
    // do something
}

fn bar() -> Option&lt;()> {
    let Ok(f) = foo() else {
        return None;
    };
}

I hated that if-statement. I realized today that I could simplify to:

fn bar() -> Option&lt;()> {
    let f = foo().ok()?;
}

And that cleaned up my code a lot. It's a tiny thing, but when it's okay to discard the error from the result, makes such a big difference when you have a lot of them!

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[-] tatterdemalion@programming.dev 22 points 11 months ago

Do you really discard errors this often? I would say almost all of my Results get propagated to the caller via ? and handled in one place near the start of the stack.

[-] kia@lemmy.ca 3 points 11 months ago

A lot of the time, I have these around places where I'm reading from a file. If reading causes an error, regardless of what the error is, I just return None and a new file is created.

[-] nous@programming.dev 17 points 11 months ago

That is a terrible time to throw away the error. Best to actually check for file not exists error and created the file only then. Other errors are important to see to debug why things are failing.

It is very annoying to have a tool tell you it failed to create a file when the file exists but it just cannot read it for some reason. You can spend ages jumping down the wrong rabbit whole if you don't realize what is happening.

[-] kia@lemmy.ca 2 points 11 months ago

Yeah that's a good point. This is a special case where the file is simply caching runtime results so errors surrounding it not being read aren't a big deal.

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