Tech Tip: Chaining user class functions

PRODUCT: 4D | VERSION: 20 | PLATFORM: Mac & Win

Published On: August 21, 2023

With the introduction of the return keyword in v20, now any user class function can be written to be chain-able. Simply return This at the end of the function. For example, given the class below:

// Class: Phrase
Class constructor($phrase : Text)
  This.phrase:=$phrase

Function question()
  This.phrase+="?"
  return This

Function exclaim()
  This.phrase+="!"
  return This

Its question() and exclaim() functions can be chained, like below:

// simple use case
$newPhrase:=cs.Phrase.new("Hello world")
$newPhrase.question().exclaim().question()
$myPhrase:=$newPhrase.phrase // "Hello world?!?"