Excel VBA is not designed to run on a separate thread because it is tightly integrated with the main Excel application. The VBA code runs within the same thread as the Excel application, and any operation performed by VBA directly affects the Excel application and its user interface.
Operating on a separate thread means running a process independently of the main application thread. This allows the main thread to remain responsive while the secondary thread performs computationally intensive or time-consuming tasks. However, Excel VBA does not support multi-threading or running code on a separate thread out of the box.
Running VBA code on a separate thread would require additional programming techniques or external libraries to simulate multi-threading behavior. One approach to achieve this is by using external libraries like the Microsoft Windows API (Application Programming Interface) or third-party libraries that provide multi-threading capabilities. However, implementing such techniques can be complex and may introduce synchronization issues or lead to instability if not done carefully.
Let’s consider an example to understand why running VBA on a separate thread can be problematic. Suppose you have a VBA macro that performs a lengthy calculation on a large dataset. If this calculation is executed on a separate thread, it can free up the main Excel application to continue responding to user interactions. However, if the user tries to interact with the worksheet while the VBA code is still executing, conflicts may arise. For example, if the user adds or deletes rows, it could interfere with the ongoing calculation, leading to incorrect results or even crashes.
To overcome the limitations of running VBA on a single thread, alternative approaches can be considered. For example, instead of directly executing time-consuming tasks within VBA, you can offload those tasks to other programming languages or environments that support multi-threading, such as using Python or C# alongside Excel. This way, you can benefit from multi-threading capabilities without compromising the stability and responsiveness of the Excel application.