Guide: match

[steveklabnik]

No description provided.

[passy]

Is there something missing here?

[steveklabnik]

Whoah whaoh. this whole section shouldn't be. My filesystem has been screwy lately....

[steveklabnik]

This is now right. Whoah.

[huonw]

I think this reasonable fine, although it doesn't mention (there's no particular need to mention them now if you have a plan):

• name bindings (possibly incl. mut x)
• nested patterns
• pattern matching on tuples, structs or tuple structs (not hugely useful at the top level, but very useful as nested patterns inside enums etc.)

Also, some things that could be mentioned at some point, but haven't got enough background:

• ref, ref mut patterns for binding a name as a reference into the matchee (these are what make pattern matching in Rust actually workable & performant)
• box and & patterns for matching through pointers (well, only Box atm) and references respectively.

[steveklabnik]

Yeah, the last two really needs pointers.

This isn't intended to be super exhaustive, so I left off name bindings on purpose. I haven't decided when to put in nested patterns, but it seems like a good plan for when I talk about Result. Matching on those other things seems good since I just talked about them.

[parir]

s/becuase/because

[steveklabnik]

Fixed, thank you.

[steveklabnik]

@huonw on the three:

• pattern matching on tuples, structs or tuple structs: I think I want to cover this when I talk about Option, because that's when I've found it most useful.

Can you think of a decent example of these two? I haven't used them enough. I do think they should be covered here.

• name bindings (possibly incl. mut x)
• nested patterns

[sfackler]

@steveklabnik here's on example of a place I've used a nested pattern:

match r.read(buf) {
    Ok(bytes) => { /* process buf */ }
    Err(IoError { kind: EndOfFile, .. }) => { /* bail out */ }
    Err(err) => { /* handle error */ }
}

[steveklabnik]

@sfackler hmmm, interesting. That uses too many details I haven't talked about already, maybe that means it's a good candidate to put later in the guide.

[steveklabnik]

After thinking about it, this is good to go for now. I'm actually going to have to introduce Option a bit earlier than I want, and so I have plans to add the other match stuff, but this should land first.

@brson r?

[nielsle]

It would be nice to write the failing code here, so the readers can try it out and experience the error for themselves.