Coroutine needed here?

Questions & Answers
1

I'm a little confused. I have a routine that loads an object from a file (using WWW and yield), and after it's loaded, I want to modify the game object that it loads into.

What's the best way to do this?

What I have now looks something like this:

void MakeObjectFromFile (url)
{
  GameObject newObj = GetObjectViaWWW (url); // returns a gameobject with the thing in it
  newObject.GetComponent(Collider).isTrigger = true;
}

GameObject GetObjectViaWWW (url)
{
   make a game object, various setup
   StartCoroutine(WaitForResponse(www));
}

public IEnumerator WaitForResponse(WWW www)
{
  yield return www;
  // check for errors
  if (www.error == null)
  etc.
}

If I understand correctly, GetObjectViaWWW will return immediately, so GetComonent(Collider) will probably fail because the coroutine is still just getting started.

I don't really want to do the post-processing in the WaitForResponse routine. Mainly, I haven't found a coding pattern I like for that, if one exists.

So is there one? Is there a preferred clean way of 'waiting for the operation to complete' when it's called in a subroutine like this? Should I set a semaphore and check it in an Update function or something?

It feels like I want to use a callback function. Which is sorta what a coroutine is, right? Can I pass a function into this somehow, essentially a callback from a callback?

2

You can do something like this:

void MakeObjectFromFile (url)
{
    //lambda version to do it inline
    GetObjectViaWWW (url, go=>go.GetComponent<Collider>.isTrigger = true);
    //or with a callback function
    GetObjectViaWWW (url, ManipulateGameObject);
}

//callback function
void ManipulateGameObject(GameObject go)
{
    go.GetComponent<Collider>.isTrigger = true;
}

//wrapper for the coroutine, stops you needing to add on StartCoroutine
void GetObjectViaWWW(string url, Action<GameObject> callback)
{
    StartCoroutine(GetObjectViaWWWCoroutine(url, callback));
}

//Action<T> is a delegate which takes one parameter, void return type
IEnumerator GetObjectViaWWWCoroutine (string url, Action<GameObject> callback)
{
    //make a game object, various setup
    yield return StartCoroutine(WaitForResponse(www));
    //do stuff with gameobject
    callback(createdGameobject);
}

public IEnumerator WaitForResponse(WWW www)
{
  yield return www;
  // check for errors
  if (www.error == null)
  etc.
}