Let's check out Clikt

Let's check out Clikt, the "Command Line Interface for Kotlin". It is a popular open source library that provides command line tooling for Kotlin! It has a rich feature set that I will explain and go over in this talk.

Transcript

1. Clikt brian plummer @plummermakes
2. Command Line Interface for Kotlin
6. /giphy ain’t nobody got time for that
7. Clikt does one job really well
8. Options and Arguments
13. val count by option()
14. val count by option().default(“1”)
15. val count: Int by option().int().default(1)
16. option(help = “Number of greetings”)
18. val name by argument()
19. val name by argument(help = “name to say hello to”)
24. val someFlag by option()
25. val someFlag by option().flag()
26. val someFlag by option(“-f”).flag()
27. val someFlag by option (“-f”).flag(default = false)
28. ./cliktsample brian Flag f has value: false Hello brian!
29. ./cliktsample -f brian Flag f has value: true Hello brian!
30. How do we get that binary? ./cliktsample
31. Gradle’s application plugin
32. ./gradlew installDist ./build/install/cliktsample/bin/ clicktsample
33. Packages us up nicely!
34. Lots of features! Let’s look at just a couple more
35. Custom Types
36. Multiple Options
37. Nested Commands
38. Prompt for input val name by option().prompt()
39. Prompt for password prompt(requireConfirmation = true, hideInput = true)
40. And much much more •Choice / Mutually Exclusive / Eager /……Options •Documenting / Formatting •Token normalization / Replacing stdin/stdout •Launch Editor / Bash Autocomplete •Exception Handing
41. And much much more
42. Why not a Kotlin lib like kotlin-argparse or kotlinx.cli? •Lack of subcommand, though that has changed •Not nearly as feature rich •Clikt tries to be consistent and intuitive •Clikt is JVM based
43. Sometimes we have to support scripts that we would rather not
44. There was a ruby script that did string interpolation
45. Legacy Kotlin
46. We can now •Isolate the legacy code •Better control on legacy code invocation •Build new features on our terms •Refactor and pull code into Kotlin
47. StranglerFig Application •Martin Fowler ~ 2004 •Create new system around the old •Gradually move functionality to new •Less risky way to replace
48. Thanks! @plummermakes