INFO: Tips to Improve Performance While Using OLE Servers (138072)

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Tip One

Here are two ways in which an object could be created using early binding:

•    Dim x As New MyClass
     Call x.MyMethod
  
  						

  -or-

•    Dim x As MyClass
     Set x = New MyClass
     Call x.MyMethod
  
  						

The latter code is faster and more efficient because it creates an instance of the object only while executing the Set statement. The former code doesn't instantiate the object until the statement that calls a method of the object.

In the former code, each call to a member of an object checks to see if it has been instantiated. If not it is instantiated at that point, the call is made. In the latter code, no such check is made, so it is faster. It is the responsibility of the application developer to ensure that an object variable has been properly instantiated before calling any of its members.

Another thing to keep in mind is that the former code guarantees that you always have a reference to an object. Therefore, even if you:

   Set x = Nothing
				

and later check:

   If x Is Nothing Then
				

x is instantiated at that point. Such a check will always return a value of False. Whereas in the latter code, you are always free to set x to Nothing and check for it correctly later.

Tip Two

While calling members of an out-of-process OLE Server such as an OLE EXE server, if you need to make repetitive calls to members that return quickly (for example, members like the height property of the Form object that don't use many instruction cycles), it will be faster to call a single method that bundles all these other "lightweight" properties into an array or returns them as parameters to this single method. This is because the time taken by the marshalling code for a cross-process call to execute is much more than what is needed to perform the task that the member does.