validator equivalent in Clap 4

[ditek]

I'm new to Clap and Rust in general and I really like Clap so far. The guide I'm following uses Clap 3 and uses the validator function for custom validation. However, it seems like this function has been deprecated and removed in this PR #3963.
The official tutorial mentions that:

you can validate and parse into any data type with Arg::value_parser

Is this the new recommended way even if I just want to validate, but let Clap parse as usual? In case it matters, I need to check if the arg matches a certain regex.

[epage]

Yes, this is the new way. The idea is to put the emphasis on parsing into a validated type ("parse, don't validate") but it does not preclude validating to a non-validated type.

Say you want to validate a string, you can use clap::builder::StringValueParser::new().try_map(|s| ...). A short-cut for this is to pass in a Fn(&str) -> Result<T, E> (and you can just return a String as T) as a value parser.

[ditek]

I understand. Thanks for answering 😊