How Can Watch Variables be Configured in a Watch Window Before Running a Debug Session in VS2017?

Question

In all of my searching, I have not come across any trick, plug-in, or setting that would allow me to pre-populate a Watch Window for use during debugging.

The well-known steps to watch a variable in Visual Studio 2017 is to set a breakpoint (perhaps on the first instance of a variable being assigned a value), then, adding the variable to a Watch Window. On subsequent runs, that watched variable should remain in the Watch Window.

Is there a way to accomplish pre-populating the Watch Window before a debugging session? I have code that runs in a timed sequence. Taking the extended time during an execution break to pause and set up a watch causes the program to crash. Such timeout crashes while setting up variable watch objects makes for difficult interaction with the debugger. Pre-populating the watch list would help considerably.

I know that I could use a technique such as using Debug.Print(...) statements, which are printed to the Output Window during code execution. However, this doesn't allow me the control and visual feedback to my debugging efforts that comes from a Watch Window.

Answer 1

Watches can only be evaluated when you are paused in the debugger, say on a breakpoint. They can't be evaluated during normal execution. Your options to get around this limiation are:

1. Add Debug.Print(...) or something similar to your code that outputs a value.
2. Similar to #1 add a TracePoint which you'll find in the actions setting of a breakpoints setting (that's the gear icon when you hover over a breakpoint). When the TracePoints are hit they will then evaluate the expression that you specficied in the actions window and log it to the Output window. The advantage of TracePoints over adding your own logging is that you can turn it off and on without building your code. More info at: https://learn.microsoft.com/en-us/visualstudio/debugger/using-breakpoints?view=vs-2019#BKMK_Print_to_the_Output_window_with_tracepoints
3. Use the VS Enterprise only feature Snapshots which is part of IntelliTrace. Basically set your breakpoints but rather than stopping on them to look at the watch just continue. Each time you stop a snapshot of the process will be taken capturing the state of your application at that time. Then once you're finished use the Diagnostic Tools window to select each of the snasphots and activate them. For each snapshot you can use the debugger just as if you stopped the application. So you can use watches and inspect etc. Of course you can't step as the app has already ran but you can go to the next snapshot etc. More info at: https://learn.microsoft.com/en-us/visualstudio/debugger/view-snapshots-with-intellitrace?view=vs-2019 and https://devblogs.microsoft.com/visualstudio/step-back-while-debugging-with-intellitrace/

Answer 2

How Can Watch Variables be Configured in a Watch Window Before Running a Debug Session in VS2017?

I'm afraid the answer is negative.For now,the Watch window can only be configured after the debug session start.It's like a runtime window only occurs during debugging.

So we can't pre-populate it before debug session for now. In other words, it's by design.

As alternative ways,you can follow Andy's detailed suggestions above.

And since your needs is meaningful in some specific debugging situation, you can also post your suggestion on development community like a user voice to add a new feature.