Using exception when `fast but no exception` is turned on.

Archived Forums Questions & Answers
1

Can I use C# exceptions when Fast but no exception optimization is turned on ?

EDIT: Test Code

using UnityEngine;
using System.Collections;
using System;

public class TestException : MonoBehaviour {
	private string exceptionMessage;
	// Use this for initialization
    void Start () {
    }

    // Update is called once per frame
    void Update () {
    
    }

    void GenerateExceptionRandomly()
    {
    	int a = UnityEngine.Random.Range(0, 2);
        if (a != 0)
    	{
	    throw new ApplicationException("Exception");
    	}
    }

    void OnGUI()
    {
	    GUILayout.BeginVertical();
	    if (exceptionMessage != null)
	    {
	    	GUILayout.Label(exceptionMessage);
	    }
	    else
	    {
	    	GUILayout.Label("No exception");
	    }
	
	    if (GUILayout.Button("Reset exception", GUILayout.Width(200), GUILayout.Height(50)))
	    {
	    	exceptionMessage = null;
	    }
	
	    if (GUILayout.Button("Random exception", GUILayout.Width(200), GUILayout.Height(50)))
	    {
		    try
		    {
		    	GenerateExceptionRandomly();
		    }
		    catch (Exception e)
		    {
		    	exceptionMessage = e.StackTrace;
		    }
	    }
    	GUILayout.EndVertical();
    }
}
2

Here’s information from Unity’s devs (as of September 2012):

  1. “Fast but no exceptions” has limitation that it will crash if exception is thrown from native code. 100% managed exceptions work fine.
  2. “Fast but no exceptions” also breaks some reflection code. Typically it is the code that tries to discover currently executing stack frame / assembly. This going to be improved with Unity 4.0.
  3. “Fast but no exceptions” improves managed->native calls by about 3x. So calls like transform.position become ~3x faster.

Source: http://forum.unity3d.com/threads/how-much-slower-is-slow-and-safe-vs-fast-but-no-exceptions.150254/#post-1033345