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serialize: use Result #13107
serialize: use Result #13107
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Yay! ❤️ The next person to take a snapshot will get to have fun with (Also, this needs a rebase.) |
Rebase already? Hah, I rebased just before submitting :-) |
This is great work. Once this clears travis, r=me. |
(cc @wycats: a magical @seanmonstar fixed all/some of your problems for you.) |
I'm a little worried about the explosion of generics when dealing with serialization things. Dealing with decodable/encodable already has a few type parameters which makes signatures a bit unwieldy, and adding another for an error seems a little sad. Is it crucial that all encoders/decoders need their own error type? Could this all possibly return |
My decoders definitely want their own Error type. I think this is just a side effect of not having yet nailed down the expected patterns for Result propagation. |
There is definitely errors that could occur besides IoError. Take this example: #[deriving(Decodable)]
struct Bar {
foo: uint
}
let json_str = "{\"foo\":false}";
// assume we've merged Parser and Decoder (a future PR)
let decoder = json::Decoder::from_str(json_str);
let bar = match Decodable::decode(decoder) {
Ok(b) => b,
Err(e) => fail!("{}", e)
}; This isn't an IoError. With Encoders, it's certainly possible that they could only return enum Foo {
Bar(~str, ~str)
}
impl<D: Decoder, E> Decodable<D, E> for Foo {
fn decode(&self, d: &mut D) -> Result<(), E> {
match *self {
Bar(ref a, ref b) => {
// i forget to use `emit_enum_variant`
d.emit_enum(|d| {
try!(d.emit_enum_variant_arg(0, |d| d.emit_str(a)));
d.emit_enum_variant_arg(1, |d| d.emit_str(b))
})
}
}
}
} A Decoder could be keeping track of a state, and notice that you emitted values wrongly, and return some @erickt As for Travis: it seems it failed downloading llvm dependencies? Can anyone give it a kick? |
I kicked off the relevant travis build, and it sounds like custom errors is necessary. Thanks for the explanation! |
Oh wow, I somehow missed a bunch of encode stuff in rustc/metadata. Working on it... |
there we go, had missed a bunch of in rustc/middle/astencode as well. Sorry for the |
@erickt r? |
@@ -187,7 +187,7 @@ pub fn phase_1_parse_input(sess: &Session, cfg: ast::CrateConfig, input: &Input) | |||
if sess.opts.debugging_opts & session::AST_JSON_NOEXPAND != 0 { | |||
let mut stdout = io::BufferedWriter::new(io::stdout()); | |||
let mut json = json::PrettyEncoder::new(&mut stdout); | |||
krate.encode(&mut json); | |||
let _ = krate.encode(&mut json); |
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You should do krate.encode(&mut json).unwrap()
here, so we'll fail instead of silently ignoring an error.
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this was just to remove the unused result warning, because stage0 has it returning ()
. I could add in the staged unwrap_
functions here as well.
Epic work. r=me with my minor comments addressed. |
@erickt just force pushed up all the FIXMEs and an unwrap_ in rustc/driver. |
@erickt i had missed a doc example, I've fixed and ran them locally to be sure. |
All of Decoder and Encoder's methods now return a Result. Encodable.encode() and Decodable.decode() return a Result as well. fixes rust-lang#12292
something else landed before bors got to this, requiring another rebase against master. |
All of Decoder and Encoder's methods now return a Result. Encodable.encode() and Decodable.decode() return a Result as well. fixes #12292
Suggest struct when completing enum closes rust-lang#13107
Add test for `try_err` lint within try blocks. Fixes rust-lang#5757 Turns out the current `try_err` implementation already skips expressions inside of a try block. When inside of a try block, `Err(_)?` is desugared to a `break` instead of normal `return` . This makes `find_return_type()` function at [this line](https://github.com/rust-lang/rust-clippy/blob/eb4d88e690c431691bc0fd8eaa9f7096ecc2a723/clippy_lints/src/matches/try_err.rs#L29) always returns `None` and skips the check. I just added a test case for try block. changelog: none
All of Decoder and Encoder's methods now return a Result.
Encodable.encode() and Decodable.decode() return a Result as well.
fixes #12292