Using r#keyword or aliases?

[SOF3]

Rust supports a syntax called "keyword identifiers", where you may call a variable r#type instead of resorting to an alias like ty.

However, it is also common to see (even in rust-src) that type is aliased as ty when used in variable names or struct fields.

Should r#type or ty be prefrred? If the latter is preferred, what about other keywords? Is there a conventional mapping from the keyword to the alternative identifier?

For example, in Java, it is common to have variables named clazz when the variable type is a java.lang.Class.

It would be useful for provide such a mapping, or otherwise to encourage use of r# in api-guidelines (especially the naming section)

[SOF3]

I think ty is a special case though, because it's too common that structs are called ty even when they don't need to.

[jyn514]

The ones I've seen are

• crate -> krate
• type -> ty
• self -> this
• mod -> module

I don't think I've actually seen anyone using keyword identifiers unless it was done by cargo fix or something.

[ThomasdenH]

I like using r#keywords! Using another name is always at least slight less clear. It may be harder to r#type though, depending on the tooling.

[SOF3]

I think r#keyword is mostly used for backward compatibility, such as reqwest::r#async in the past.

[Ixrec]

Compatibility across epochs/editions is definitely the reason raw keywords / r#keyword were added to the language, and the use case they're designed for.

While we theoretically could replace some aliases with raw keywords instead, aliases have been the only option for so long that they're the de facto standard, so we'd need a pretty strong motivation to switch. And personally, even if we could boil that ocean, I like aliases better for subjective aesthetic reasons and because they're fundamentally a simpler solution to this problem (grokking how raw keywords help with the cross-epoch lexing problem may not be that hard, but it's not trivial either).

[SOF3]

Also recall how difficult it is to figure out hwo to use raw keywords in quote.

[Buer-Nahida]

I like r#keyword, because in I using cplusplus time, I always use k_var_name to name the variable when is a the name for variable is a duplicate of a keyword duplicate of a keyword