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0 pointsmasklinn2y ago0 comments

> Without the let, I'd have to do a match statement followed by an unwrap just to check if a field in an enum is set.

You... would not?

An `if let` trivially desugars to a `match`.

    if let <pat> = <expr> {
        ...
    }

becomes

    match <expr> {
        <pat> => {
            ...
        }
        _ => {}
    }

0 comments

trane_project2y ago

See my example. I am trying to extract the value of an optional field in the enum. That's where the unwrap comes in.

masklinnOP2y ago

What I wrote up is the spec-defined desugaring of a single-branch `if let`, aside from desugaring bugs there should be no counter-example.

The snippet you link to should be replaceable by something along the lines of

    match &passages.asset {
        TranscriptionAsset::Track {
            artist_name: Some(artist_name),
            ..
        } => {
            metadata
                .entry(ARTIST_METADATA.to_string())
                .or_default()
                .push(artist_name.clone());
        }
        _ => {}
    }

no `unwrap` needed. I don't know where you got that idea.

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