[rust-dev] Why no "@Override" analogy?

Christoph Husse thesaint1987 at googlemail.com
Wed Jul 16 12:16:16 PDT 2014


doh. okay. it has a lot to do with it but it is enabled by default then :D.
slowly climbing the learning curve lol

On Wednesday, July 16, 2014, Steven Fackler <sfackler at gmail.com> wrote:

> I don't see what this has to do with @Override. @Override causes the
> compiler to check to make sure that the method signature matches a
> supertype method. Rust always enforces that check inside of a trait
> implementation block. This kind of thing is always illegal:
>
> impl SomeTrait for Foo {
>     fn some_random_method_that_isnt_part_of_some_trait(&self) { ... }
> }
>
> The visitor trait is huge, and 99% of use cases don't need to visit every
> possible part of the AST, so there are default implementations of all of
> the methods that simply fall through to visit all of the subparts. That
> comment is just saying that if you *do* want to visit everything, you have
> to manually check to make sure you're overriding everything.
>
> Steven Fackler
>
>
> On Wed, Jul 16, 2014 at 11:59 AM, Christoph Husse <
> thesaint1987 at googlemail.com
> <javascript:_e(%7B%7D,'cvml','thesaint1987 at googlemail.com');>> wrote:
>
>> This comment from "syntax::visit::Visitor" really gives me a headache:
>>
>> /// If you want to ensure that your code handles every variant
>> /// explicitly, you need to override each method.  (And you also need
>> /// to monitor future changes to `Visitor` in case a new method with a
>> /// new default implementation gets introduced.)
>>
>> I kindof thought we would have passed this :(.
>> "I" need to check for future changes :O? How? Closed source 3rd party,
>> just to name one example, or simply oversight. Okay, an IDE could warn
>> too. But we dont' have one right now and in the past it didn't seem
>> like this would have helped much.
>>
>> What's the rationale behind this decision?
>>
>> Why no: #[Impl] attribute or something?
>>
>> Sry, if I bring up old discussions but it was kinda hard to come up
>> with a search term for this.
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>>
>
>
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