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Oracle Visual Builder: Applications That Outlive Their First Release · Module 8 · Action chains and events

Conditions and branching

Lesson 81 of 176 · 2 min

Making a decision inside a chain, and KEEPING THE CONDITION READABLE BY THE PERSON WHO INHERITS IT. A chain that never branches is rare. A chain whose branches nobody can follow is what an application becomes if this lesson is skipped. THE MECHANISM IS A CONDITION STEP WITH TWO PATHS, AND IT IS UNREMARKABLE. What is remarkable is how quickly it becomes unreadable, because a visual branch takes real space and the eye loses which path it is on. THE FIRST RULE IS THAT THE CONDITION SHOULD BE READABLE AS A SENTENCE. A compound expression with three comparisons and two operators is correct and is not readable in a small box — nobody inheriting it will work out what it means, and they will not delete it either, so it becomes permanent and unexamined. Name it: put the answer in a well-named variable and branch on that. THE SECOND IS…

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In this module: Module 8 · Action chains and events

  1. 1What an action chain isFree preview
  2. 2Events: what can start one
  3. 3The common actions
  4. 4Conditions and branching
  5. 5Chains that call chains
  6. 6Waiting: asynchronous steps
  7. 7Failure inside a chain
  8. 8JavaScript, and when to reach for it
  9. 9Keeping a chain readable
  10. 10Debugging one that misbehaves
  11. 11Logic that does not belong here
  12. 12What breaks: four action chain failures
  13. 13Lab briefing · A chain that survives being read