Add documentation for env

[vmalloc]

No description provided.

[kaj]

Nice and simple. Apart from two minor issues, I think this looks just fine (I'm not the maintainer, though).

[kaj]

By the way, maybe the flag hide_env_values (useful to avoid printing out sensitive data from environment in help messages) should also be mentioned here.

[vmalloc]

@kaj I didn't know that one! Couldn't find it in the source though. Can you point me to a resource detailing it?

[kaj]

@kaj I didn't know that one! Couldn't find it in the source though. Can you point me to a resource detailing it?

It's listed at https://docs.rs/clap/2.33.0/clap/struct.Arg.html#method.hide_env_values (but the actual documentation is marked as TODO). I use it in a project and it works fine.

[vmalloc]

@kaj I'm not sure I get what that does... Using env by default does not output the value being used anywhere... what does that hide exactly?

[kaj]

@kaj I'm not sure I get what that does... Using env by default does not output the value being used anywhere... what does that hide exactly?

It does, in the --help output. Try the example given in this crate:

env RETRIES=7 cargo run --example=env -- --help

[vmalloc]

@kaj ooooh I see. Ok, will add it then

[vmalloc]

@kaj I added documentation for hide_env_values

[TeXitoi]

Thanks for the contribution!

Note that this is pure clap documentation, and I generally avoid to doubling this documentation. But env is a frequently asked feature, thus I'm OK to put it here.