Simplify clap derive definition

[tranzystorekk]

Highlights:

• Make short and long attributes automatically parse field names
• Add possible_values
• Change render field type to PathBuf

[dbrgn]

Make short and long attributes automatically parse field names

Hi, we discussed automatically parsed field names here: https://github.com/dbrgn/tealdeer/pull/108#discussion_r730452346

I'd tend towards keeping the explicit commands, mostly for consistency and because this way people can read/grep the commands without knowing how the clap auto-generated flag names work. For example, if someone wants to know how the clear-cache command works and searches the source code for that, there would be no instances that can be found.

Do you disagree with that?

[dbrgn]

Add possible_values

Nice, I didn't know about this option. Unfortunately it causes a line wrap because it's a bit more verbose:

vs

@niklasmohrin what's your opinion, worth it or not? I don't think the possible_values features will bring any additional benefits, because the validation itself happens on the FromStr level (but I might be wrong about that). If it's purely convenience, I think I'd stick with the manually controlled variant, because it's more compact.

[tranzystorekk]

Make short and long attributes automatically parse field names

Hi, we discussed automatically parsed field names here: #108 (comment)

I'd tend towards keeping the explicit commands, mostly for consistency and because this way people can read/grep the commands without knowing how the clap auto-generated flag names work. For example, if someone wants to know how the clear-cache command works and searches the source code for that, there would be no instances that can be found.

Do you disagree with that?

Something rubs me the wrong way when looking at the explicit version, but I cannot argue with your standpoint 😅

[tranzystorekk]

Regarding possible_values, it might indeed be just a cosmetic change, unless FromStr impl changes to Err = Infallible, but then the validation would be split into two separate places in code...

One potential gain is if we switch to clap-generated completion which completes possible_values.

[dbrgn]

One potential gain is if we switch to clap-generated completion which completes possible_values.

That's a very good point, I'm convinced 😄

[tranzystorekk]

One more thought - should we leave a comment in code with a brief rationale for leaving flag names explicit?

[dbrgn]

@tranzystorek-io thank you for the updates! Yes, such a comment would be helpful. Would you like to add one? Afterwards this should be ready to merge!