Why Do I Need to Set Objects to Nothing in VBA?
I received a version of the following question from a reader the other day:
Why do I need to set objects to Nothing? Something about releasing resources. Doesn't seem to affect performance.
Here's a modified version of my response, with links to some useful articles on the topic:
Generally speaking, you don't usually need to explicitly set object variables to Nothing in VBA as the language cleans them up automatically when the procedure exits.
Technically speaking, VBA takes care of incrementing the COM reference count when an object is created and decrementing the reference count when the object variable goes out of scope. One thing you do need to be careful to avoid is creating circular references, though that's mostly an issue if you have pairs of classes that refer to each other via something like a.Parentand.Childclass property.
Referenced articles
Memory Management in VBA: 3 Keys to Avoiding Memory Leaks
Managing memory in VBA is a piece of cake, especially if you follow three simple guidelines.
Managing Memory in COM
We continue on with our restaurant analogy to explain the concept of reference counting and COM object cleanup.
Scope vs. Extent in VBA
Master the extent and scope of your VBA variables for code that’s efficient, effective, and easy to maintain.
Reference Counting’s Fatal Flaw: Circular References
We look at several types of circular references along with a handy tool that you can use to help identify circular references in your own code.
Cover image created with Microsoft Designer