# Two little proposals **URL:** \ **Category:** language design\ **Created:** [May 27, 2015, 8:32pm UTC](https://internals.rust-lang.org/t/two-little-proposals/2148 "2015-05-27T20:32:33Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Xirdus](https://avatars.discourse-cdn.com/v4/letter/x/b4bc9f/32.png) [@Xirdus](https://internals.rust-lang.org/u/Xirdus)\ **Post date:** [May 27, 2015, 8:32pm UTC](https://internals.rust-lang.org/t/two-little-proposals/2148/1 "2015-05-27T20:32:33Z")
Hi, I have two tiny ideas that could improve language a little. 1. Make it a warning (or even an error) to declare a variable of type `()`, except when it’s due to generic type resolution. This is pretty useless, but some people new to Rust might do it by mistake, for example by saving the result of assignment. Also would make finding errors like unwanted semicolon easier in some cases. 2. Inferring the type of created object. It’s one of few places in Rust where full type declaration is needed, and it’s almost always superfluous and looks like code duplication (most notably in `new()` methods of structs). This would require a new keyword though, I think, to differentiate from code blocks - for example, `make`, used like this: ```rust struct OverlyLongName { foo: i32 } impl OverlyLongName { fn new() -> OverlyLongName { make { foo: 5 } } } ``` What do you think? ---
**Author:** ![japaric](https://sea2.discourse-cdn.com/flex002/user_avatar/internals.rust-lang.org/japaric/32/28_2.png) [@japaric](https://internals.rust-lang.org/u/japaric)\ **Post date:** [May 27, 2015, 8:54pm UTC](https://internals.rust-lang.org/t/two-little-proposals/2148/2 "2015-05-27T20:54:24Z")
re 2, you can use the `Self` keyword to avoid typing the long name in type signatures: ```rust impl OverlyLongName { fn new() -> Self { OverlyLongName { foo: 5 } } } ``` However you still have to type the long name in the struct initialization. It would be nice if you could initialize the struct as `Self { foo: 5 }`, I’d be in favor of that. re 1, you could create a custom lint, out of the standard library, that catches the behavior you describe. If the lint proves to be popular you could propose it for inclusion in the standard library via an [RFC](https://github.com/rust-lang/rfcs). I don’t have experience with custom lints, but [rust-clippy](https://github.com/Manishearth/rust-clippy) looks like a good place to start. ---
**Author:** ![Xirdus](https://avatars.discourse-cdn.com/v4/letter/x/b4bc9f/32.png) [@Xirdus](https://internals.rust-lang.org/u/Xirdus)\ **Post date:** [May 27, 2015, 9:05pm UTC](https://internals.rust-lang.org/t/two-little-proposals/2148/3 "2015-05-27T21:05:52Z")
> [@japaric](#): > > re 2, you can use the Self keyword to avoid typing the long name in type signatures: Last time I checked, the guidelines said using Self in other contexts than trait declaration was a bad practice. Has it changed in the last few months? Also, the concept I've described would be far more general than Self - you could use it in any context, e.g. to initialize a temporary used as an argument to some function. > [@japaric](#): > > I don't have experience with custom lints, but rust-clippy looks like a good place to start. Wow, nice link! I didn't know such custom lints are possible - certainly will take a look. Thanks! ---
**Author:** ![japaric](https://sea2.discourse-cdn.com/flex002/user_avatar/internals.rust-lang.org/japaric/32/28_2.png) [@japaric](https://internals.rust-lang.org/u/japaric)\ **Post date:** [May 27, 2015, 9:33pm UTC](https://internals.rust-lang.org/t/two-little-proposals/2148/4 "2015-05-27T21:33:38Z")
> Last time I checked, the guidelines said using Self in other contexts than trait declaration was a bad practice. Has it changed in the last few months? I'll admit that I haven't checked the rust-guidelines in a long time, but I don't recall such directive. And I'm actually under the impression that only recently we started allowing `Self` inside `impl` blocks. (In fact, I realized that it was possible because I saw [this PR](https://github.com/rust-lang/rust/pull/25687)) > Also, the concept I've described would be far more general than Self - you could use it in any context, e.g. to initialize a temporary used as an argument to some function. Oh, right, I see. That I'm not so in sure about. I feel that struct initialization is not that common to warrant a new syntax just for it. Of course, just my opinion 🙂 ---
**Author:** ![phaylon](https://sea2.discourse-cdn.com/flex002/user_avatar/internals.rust-lang.org/phaylon/32/62_2.png) [@phaylon](https://internals.rust-lang.org/u/phaylon)\ **Post date:** [May 27, 2015, 9:59pm UTC](https://internals.rust-lang.org/t/two-little-proposals/2148/5 "2015-05-27T21:59:15Z")
About the type name thing: I have thought about it in the past and I’d personally be in favor of reusing `_` for type name deduction, if it were implemented. So you’d have `_ { ... }` for named structs and `_::Variant` for enums. I could also see `_(...)` for tuple structs, but I’m not sure that would be sane syntactically. I would prefer `_` for the symmetry with type inference in generics, e.g. `.connect::>()`. ---
**Author:** ![Xirdus](https://avatars.discourse-cdn.com/v4/letter/x/b4bc9f/32.png) [@Xirdus](https://internals.rust-lang.org/u/Xirdus)\ **Post date:** [May 27, 2015, 10:55pm UTC](https://internals.rust-lang.org/t/two-little-proposals/2148/6 "2015-05-27T22:55:45Z")
Right, forgot about `_`. It has this special meaning that’s very appropriate here - although, I fear the special-char-fest will make the code much less pleasant to read. Still, it’s “less” breaking than new keyword, so has bigger chances of being chosen as RFC. ---
**Author:** ![system](https://sea2.discourse-cdn.com/flex002/user_avatar/internals.rust-lang.org/system/32/14092_2.png) [@system](https://internals.rust-lang.org/u/system)\ **Post date:** [March 25, 2019, 8:24am UTC](https://internals.rust-lang.org/t/two-little-proposals/2148/7 "2019-03-25T08:24:36Z")
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