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Q138072: INFO: Tips to Improve Performance While Using OLE Servers

Article: Q138072
Product(s): Microsoft Visual Basic for Windows
Version(s): 4.00
Operating System(s): 
Keyword(s): kbVBp400
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Standard Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition, 16-bit, for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 16-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows, version 4.0 
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SUMMARY
=======

This article lists tips to keep in mind when instantiating an OLE server object,
when calling a method, or when using a property of the object.

MORE INFORMATION
================

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.

Additional query words: optimization speed quick 4.00

======================================================================
Keywords          : kbVBp400 
Technology        : kbVBSearch kbAudDeveloper kbVB400Search kbVB400 kbVB16bitSearch
Version           : 4.00
Issue type        : kbinfo

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