completions:Supportaddingadditionalcodetocompletevalues

For some argument values, the bash-completions may want to include additional logic for what type of value to complete, rather than allowing arbitrary strings. For instance, an option might accept a path to a file that exists; bash has a mechanism for that. Or, an option might accept the name of a git ref that exists; that's something more easily implemented in the program in Rust. Either way, it makes sense to augment clap's completion logic.

This also argues for implementing the completions by calling the program at runtime, rather than via shell; that way, arbitrary logic in Rust can determine what to complete, rather than providing a template system to feed in shell code (ick).

该提问来源于开源项目：clap-rs/clap