Adding methods, properties, and events

Testing the DLL

Using APL+Win, an instance of the DLL is created as shown in Figure 10.

Figure 10. APL+Win

Using APLX, an instance of the DLL is created as shown in Figure 11.

Figure 11. APLX

Using Dyalog, an instance of the DLL is created as shown in Figure 12.

Figure 12. Dyalog

APL+Win and APLX are consistent in the enumeration of the events, methods, and properties of the DLL. However, it is unclear why Dyalog is unable to see the event.

Demonstration

⎕wi '?MyProperty'

The property MyProperty is a read/write property that is numeric.

⎕wi 'xMyProperty' ⍝ Read
0
⎕wi 'xMyProperty' 100.75 ⍝ Write
⎕wi 'xMyProperty' ⍝ Read
101

There appears to be an inconsistency! On closer examination of the code, it is apparent that the DLL coerces the value of the property to integer; hence, the result is 101 instead of 100.75.

public int MyProperty
{
get { return myVar; }
set
{
MyEvent();
myVar = value;
}
}

This property will also raise the event MyEvent upon the value of the property being changed. However, the event was raised in the previous assignment but I had not specified an event handler. An event handler is specified in the usual manner, thus:

⎕wi 'onXMyEvent' '0.01×+\10/1' ⍝ Specify event handler
⎕wi 'xMyProperty' 190254 ⍝ Expect handler to run
0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1
⎕wi 'xMyProperty' ⍝ Verify
190254

The event handler did fire and ran the APL handler; any APL+Win function may be called by the handler.

The method eventm also raises the event MyEvent.

⎕wi 'Xeventm' ⍝ Call method & expect MyEvent to fire

The method MMethod simply returns a static result:

⎕wi 'XMMethod' ⍝ This method returns a string
Ajay Askoolum

Finally, the method MyMethod takes a single argument and returns it incremented by 10.

⎕wi '?MyMethod'
XMyMethod method:
Result@Long ← ⎕WI 'XMyMethod' numarg@Long
⎕wi 'XMyMethod' 190254
190264

Although the methods, properties, and events in this demonstration C# COM DLL are simple, it is clear that it is now possible to write COM servers in the Microsoft flagship language, C#, for deployment with APL. Moreover, the template developed in this article for building and deploying such DLLs is minimalist, as would become clear from a study of the subject. For instance, I have completely circumvented the issues relating to strong names, the Global Assembly Cache and the debate related to managed code.