Experiencing different behavior between object initialization in declaration vs. initialization in constructor
c#, winforms
Solution
I thought that these two styles of object initialization were identical, but it seems not to be the case.
Not quite.
In the first case, the `CameraWrapper` constructor is called after the base class constructor for `Form`. In the second case, the `CameraWrapper` constructor is called, then the base class constructor, then the `Form1` constructor body.
It's possible that something within the `Form` constructor affects the execution of the `CameraWrapper` constructor.
Problem
This is a WinForms C# application. The following two snippits show two different ways of initializing an object. They are giving different results. This works as expected: ``` public partial class Form1 : Form { private CameraWrapper cam; public Form1() { cam = new CameraWrapper(); InitializeComponent(); } ``` This does not work (details below): ``` public partial class Form1 : Form { private CameraWrapper cam = new CameraWrapper(); public Form1() { InitializeComponent(); } ``` Inside `CameraWrapper` I am using a third-party SDK to communicate with a camera. I register with an event on the SDK which is called when results are available. In case 1 (initialization inside constructor), everything works as expected and the event handler inside `CameraWrapper` gets called. In case 2, the event handler never gets called. I thought that these two styles of object initialization were identical, but it seems not to be the case. Why? Here is the entire `CameraWrapper` class. The event handler should get called after a call to `Trigger`. ``` class CameraWrapper { private Cognex.DataMan.SDK.DataManSystem ds; public CameraWrapper() { ds = new DataManSystem(); DataManConnectionParams connectionParams = new DataManConnectionParams("10.10.191.187"); ds.Connect(connectionParams); ds.DmccResponseArrived += new DataManSystem.DmccResponseArrivedEventHandler(ds_DmccResponseArrived); } public void Trigger() { SendCommand("TRIGGER ON"); } void ds_DmccResponseArrived(object sender, DmccResponseArrivedEventArgs e) { System.Console.Write("Num barcodes: "); System.Console.WriteLine(e.Data.Length.ToString()); } void SendCommand(string command) { const string cmdHeader = "||>"; ds.SendDmcc(cmdHeader + command); } } ```