More powerful shell completion
bartekpacia opened this issue · comments
Checklist
- Are you running the latest v3 release? The list of releases is here.
- Did you check the manual for your release? The v3 manual is here.
- Did you perform a search about this feature? Here's the GitHub guide about searching.
What problems are there currenty?
-
shell completions is only possible for commands - not for flags
-
ShellCompletionFunc
does not provide what the user has already entered in the prompt
What problem does this solve?
Currently urfave/cli
allows for customizing shell completion only for commands.
The Go module that does the best job at shell completions is cobra. Here are docs for it. urfave/cli
is not Cobra and I hope it will never become one – it's much more lightweight, minimal, and fun - but I strongly believe that shell completions are a very useful feature.
Proposed solution
ShellComplete
func for flags, for example:
cli.StringFlag{
Name: "region-id",
Aliases: []string{"id"},
Value: "",
Usage: "region to upload data to",
ShellComplete: func(ctx context.Context, c *cli.Command) {
fmt.Println("us-central1")
fmt.Println("us-east1")
fmt.Println("eu-west1")
},
},
Additionally, both ShellComplete
on flags and on command should provide the content of the prompt, so the developer can e.g. filter out duplicated completions:
cli.Command{
Name: "run",
ShellComplete: func(ctx context.Context, c *cli.Command, args []string) []string {
options := []string{"alpha", "bravo", "charlie", "delta"}
if err != nil {
return
}
completions := []string{}
for _, option := range options {
if slices.Contains(args, option) {
continue
}
completions = append(completions, option)
}
return completions
},
}
To avoid reinventing the wheel, completion shell scripts could be taken from Cobra (link). Deep dive & research is required to see if it fits into urfave/cli.
Summary of proposed changes
-
change type of
ShellCompleteFunc
from:type ShellCompleteFunc func(ctx context.Context, c *Command)
to:
type ShellCompleteFunc func(ctx context.Context, c *Command, args []string, toComplete string) ([]string, ShellCompDirective)
The presence and name of
ShellCompDirective
is tentative – but it's useful in Cobra.This ideally should be done before v3 stable gets released.
-
add
ShellComplete
field to all the flags –StringFlag
,IntFlag
. (What aboutBoolFlag
?)
Describe alternatives you've considered
None.
@bartekpacia I love this! Most of my recent programmable completion experience has been with click so the signature changes you are recommending make perfect sense to me.
oh, and to answer your question about BoolFlag
: idk offhand, so try out an implementation and see how it feels?