Understanding Deferreds

Contents:

• Introduction to Deferred
  • What is a Deferred?
  • A Synchronous Problem
  • A Deferred Solution
• Deferred Inline Callbacks
  • When to use it
  • How to use it
• Deferred Callback Propagation
  • Callbacks and errbacks are always created in pairs
  • When a chain of callbacks and errbacks is useful
  • Multiple Callbacks for a single Deferred
  • An errback calling a callback and continuing as-normal
• Delaying Deferreds
  • Reactor.CallLater
  • task.deferLater
  • task.LoopingCall
• Deferred Failures
  • Failure.value()
  • Failure.check()
• Cancelling a Deferred
  • When it is useful
  • How to use it
• Pre-Called Deferreds
  • example
• Timing-Out a Deferred
  • When it is useful
  • How to use it
• Using The DeferredList
  • When to use it
  • How to use it
  • Other Useful Information: Parameters
• Using the Deferred Semaphore
  • When to use it
  • How to use it
• Chaining Deferreds
  • When to use it
  • How to use it
• Common Gotchas
  • yield not returning anything
  • Not waiting for a function that returns a Deferred