Confused about Coroutines

Question

I'm almost convinced I'm seeing a bug, but this is an entirely new concept for me, so I need some help to understand what's going on. Here's a somewhat simplified version:

static function Initialize() { Debug.Log("EventManager.Initialize() called"); if (initialized) return; Debug.Log("EventManager.Initialize() 1"); eventQueue = new PriorityQueue(); initialized = true; Debug.Log("EventManager.Initialize() 2"); DoLoop(); Debug.Log("EventManager.Initialize() 3"); }

static private function DoLoop() { Debug.Log("Enter Loop()"); while (true) { Debug.Log("Top of Loop() loop"); while (eventQueue.Count) { // do something useful } Debug.Log("Before Loop() wait"); yield WaitForSeconds(1.0); } Debug.Log("Exit Loop()"); }

What's weird is I never see "Enter Loop()" in the console (or anything from DoLoop()), but I see the "Initialize 1", 2, and 3. If I comment out the while (true) loop, I'll see both the "Enter Loop()" and "Exit Loop()", but otherwise neither. What's going on?

Answer 1

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Answer by KvanteTore · Apr 06, 2010 at 07:06 AM

When a coroutine is called, it does not automatically run through to completion. It returns the body of the routine embedded in an object implementing the IEnumerator interface. Each time MoveNext is called on the object, the coroutine continues until the next yield, and returns the yield argument (in your case an instance of WaitForSeconds).

When writing scripts in C#, this is explicit. You have to start a corutine with StartCoroutine(coroutine());, where the IEnumerator is passed to the unity engine, and called at the appropriate times depending on the [YieldInstructions][2] returned from the IEnumerator.

In Javascript, I believe the compiler determines which routines are coroutines, and automatically calls StartCoroutine automatically, however apparently not from static routines.

TLDR; do as Eric suggested, remove both instances of static.

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runevision ♦♦ · Apr 06, 2010 at 09:37 AM 0

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Re the scripting language name, it is consistently referred to as Javascript in the Unity manual and in other official written Unity materials.

KvanteTore · Apr 06, 2010 at 11:14 AM 0

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@$$anonymous$$une ok. thx :)

Eric5h5 · Apr 06, 2010 at 05:03 PM 1

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Javascript automatically uses StartCoroutine from anywhere, not just Update etc.

KvanteTore · Apr 06, 2010 at 11:11 PM 0

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@Eric5h5. Ok, that's kind of neat and kind of scary... updated the last statement to reflect this.

Answer 2

Answer by Eric5h5 · Apr 06, 2010 at 05:24 AM

Remove both instances of "static".

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Confused about Coroutines

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