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Stop writing CLI validation. Parse it right the first time. (hackers.pub)
submitted 1 year ago by to c/programming@programming.dev
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[–] 5 points 1 year ago (2 children)

Clap has dependent options and mutually-exclusive argument groups built-in: https://docs.rs/clap/latest/clap/_derive/_tutorial/index.html#argument-relations

For the environment-specific requirements, you can use compiler feature flags...

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  • [–] 6 points 1 year ago (1 child)

    Mentioned this to the other commenter, but this doesn't use the type system to enforce the mutual exclusivity constraint. In Rust, the main way to do that via the type system is through enums.

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  • [–] 3 points 1 year ago

    Ah, fair enough. Not sure how to do that then.

    I was gonna say, I feel like the current method does a good enough job documenting that validation has happened, but I guess you do want it reflected in the structure of the type, so that the code that takes the information from the struct can safely make the assumption that some of the options don't exist. And then, yeah, it would be nice to not need a separate parsing step for that.

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