Databases
StackOverflow2013
Postsdbo
POEvent Subscription Lost when Passing Instance Object
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POEvent Subscription Lost when Passing Instance Object
    primarykey
    data
    text
    <p>I have created an external class (<code>TheClass</code>) with an event (<code>TheEvent</code>) and subscribe to it from within another class's Panel constructor:</p> <pre><code>public aPanel() { ... theClassInstance.TheEvent += new WaitCallback(aMethod); ... } </code></pre> <p>Later in the program, I call a method passing <code>theClassInstance</code> as the only parameter</p> <pre><code>bMethod((object)theClassInstance); </code></pre> <p>where</p> <pre><code>public void bMethod(object inputTheClassInstance) { ... } </code></pre> <p>Knowing that the input object is of type <code>TheClass</code>, I do the following:</p> <pre><code>public void bMethod(object inputTheClassInstace) { TheClass theClassInput = (TheClass)inputTheClassInstace; ... } </code></pre> <p>Later in <code>bMethod()</code> I call a method <code>RaiseEvent()</code> exposed by <code>theClassInput</code> which will actually trigger the event. In <code>RaiseEvent()</code> I have</p> <pre><code>if(this.TheEvent != null) TheEvent(); </code></pre> <p>to make sure something is subscribed to the event but <code>this.TheEvent</code> equates to null. If I place the subscription within <code>bMethod()</code></p> <pre><code>bMethod(...) { ... theClassInput.TheEvent += new WaitCallback(aMethod); ... } </code></pre> <p>it works just fine but I would like to keep it in the Panel's constructor. I figured that because <code>theClassInput</code> is pointing to the same object as <code>theClassInstance</code> it wouldn't make a difference which triggers the event. Any thoughts on how I can keep the subscription in the constructor while calling it from within <code>bMethod()</code> using <code>theClassInput</code>?</p>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USFlimzy
    1. USjohn
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POEvent Subscription Lost when Passing Instance Object
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POEvent Subscription Lost when Passing Instance Object
      1. This table or related slice is empty.
      1. VTUpMod
    1. COIf I read correctly, it should be possible to subscribe from the Panel.ctor. Do verify you're dealing with the same instance (write theClassInput.GetHashCode() with Debug.WriteLine)
      singulars
      1. POEvent Subscription Lost when Passing Instance Object
      1. USHenk Holterman
    2. COIt's really hard to follow code when it's presented in tiny snippets like this, especially with names like "bMethod", "TheClass" and "TheEvent". Please show a short but *complete* example which demonstrate the problem. Normally this would *not* be an issue.
      singulars
      1. POEvent Subscription Lost when Passing Instance Object
      1. USJon Skeet
    3. COHow unequivocally certain are you theClassInstance is the same instance as theClassInput?
      singulars
      1. POEvent Subscription Lost when Passing Instance Object
      1. USJimmy Hoffa
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload