${default} not interpolated into help if using vars

[mitar]

type cli struct {
  Config string `type:"path" default:"${config_file}" help:"Default: ${default}"`
}

func main() {
  kong.Parse(&cli,
    kong.Vars{
      "config_file": "~/.app.conf",
    })
}

This prints in help Default: ${config_file} and not Default: ~/.app.conf.

[alecthomas]

I think what will need to happen is that Kong should iteratively resolve variables until none remain unresolved.

[mitar]

Or just first interpolate default, and then interpolate help?

[alecthomas]

That won't solve interpolation ordering issues on other fields. For example, enum would have the same issue.