Default casing for value names

[FintanH]

Hey 😊

I noticed that the default casing for value names is upper case, for example:

#[derive(Debug, Clone, PartialEq, Eq, Parser)]
pub struct SyncSettingsArgs {
    /// Sync with at least N replicas.
    #[arg(long, short, default_value_t = 3)]
    pub replicas: usize,
    /// Sync with the given list of seeds.
    #[arg(long = "seed", action = clap::ArgAction::Append, value_name = "nid")]
    pub seeds: Vec<NodeId>,
    /// How long to wait for syncing to complete.
    #[arg(long, value_name = "seconds", default_value_t = DEFAULT_SYNC_TIMEOUT.as_secs())]
    pub timeout: u64,
}

will output:

  -r, --replicas <REPLICAS>  Sync with at least N replicas [default: 3]
      --seed <nid>           Sync with the given list of seeds
      --timeout <seconds>    How long to wait for syncing to complete [default: 9]

I was wondering if there is a way to have the default be lowercase, i.e. <replicas> in this case instead, without having to label it with value_name? I tried looking around but couldn't seem to see if this possible at the moment.

[epage]

You can use the rename_all command attribute

[FintanH]

Thanks for the response @epage 😊 I'm likely holding this wrong so might need some guidance. I've got a reproducible here https://github.com/FintanH/sync-clap-mvp/blob/master/src/lib.rs#L310.

Running the command through cargo I get:

cargo run -p sync -- --help            
    Finished dev [unoptimized + debuginfo] target(s) in 0.03s
     Running `target/debug/sync --help`
Sync repositories to and from the network

Usage: 
  rad sync [--fetch | --announce] [--rid <rid>] [--timeout <secs>] [--debug] [--seed <nid>]
  rad sync status [--sort-by <field>]
  rad sync --inventory

Commands:
  status  Display the whether other nodes are synced our out-of-sync with this node's signed references
  help    Print this message or the help of the given subcommand(s)

Options:
      --rid <rid>            Repository Identifier to be synchronized
      --debug                Output debug information, if any
  -v, --verbose              Out verbose information, if any
      --fetch                When `--fetch` is specified, any number of seeds may be given using the `--seed` option, eg. `--seed <nid>@<addr>:<port>`
      --announce             When `--announce` is specified, this command will announce changes to the network. Can be used in tandem with `--fetch` to also fetch beforehand
      --inventory            If `--inventory` is specified, the node's inventory is announced to the network. This mode ignores the `--rid` argument
  -r, --replicas <REPLICAS>  Sync with at least N replicas [default: 3]
      --seed <nid>           Sync with the given list of seeds
      --timeout <seconds>    How long to wait for syncing to complete [default: 9]
  -h, --help                 Print help
  -V, --version              Print version

It's still printing REPLICAS. I've also tried adding it to the field https://github.com/FintanH/sync-clap-mvp/blob/master/src/lib.rs#L321, and also the struct https://github.com/FintanH/sync-clap-mvp/blob/master/src/lib.rs#L254 -- all with no luck 🤔

[epage]

Sorry, I forgot how busted rename_all is. We are tracking it in #3709.

[FintanH]

Heh, all good! Glad to hear I'm not losing my mind 🙃 Is there anything I can do to help with that task? I'm happy to try dig in if you can point me where to start looking 😁

[epage]

Huh, I normally don't look at breaking changes until we're ready but with the suggested way of implementing this, we can

1. Implement the new attributes
2. Deprecate the existing attribute (which includes generating a dummy function we call to produce a deprecation warning)
3. Condition-out the attribute on unstable-v5

The code is at

• clap/clap_derive/src/attr.rs

  Line 79 in 5e3386b

  let magic = match name_str.as_str() {

• clap/clap_derive/src/item.rs

  Line 822 in 5e3386b

  Some(MagicAttrName::RenameAll) => {

• clap/tests/derive/naming.rs

  Line 367 in 5e3386b

  fn test_rename_all_is_propagated_from_enum_to_variant_fields() {

• clap/tests/derive/rename_all_env.rs

  Line 10 in 5e3386b

  #[command(rename_all_env = "kebab")]

We'll want to check how these propagate from enums to struct variant fields.