VBA-SafeTimer

Reliable, no-crash timer for VBA. Code can be debugged and stopped safely.

Windows notes:

• SetTimer is used for calling back VBA code at regular intervals
• VBA does all the heavy lifting
  • memory allocation - no need for side-allocations
  • break mode check - so that timer calls are ignored / skipped in break / debug mode
  • timer cleanup - timer is removed when the corresponding form is destroyed

Mac notes:

• not implemented, yet

Installation

Download the latest release.

Just import the following code modules in your VBA Project:

• SafeTimer.cls
• LibTimers.bas
• TimerForm.frm - Alternatively, this can be easily recreated from scratch in 2 easy steps:
  • insert new form
  • rename it to TimerForm

Usage

Just add a SafeTimer instance WithEvents to any of your classes. The TimerCall event will be raised at the desired interval. See demo.

Optionally, you can pass a Variant when you call SafeTimer.StartTimer so that it is passed back in the event.

Implementation

Windows:

• each instance of SafeTimer class calls SetTimer when its StartTimer method is called
• each callback call (at set interval) to SafeTimer.TimerProc will raise a TimerCall event to any listening classes
• a single call to VariantCopy is made so that we can copy memory (no kernel.dll needed)
• a few assmebly bytes (just 23 on x64 and just 20 on x32) are used to redirect the timer call to the correct SafeTimer instance

Mac:

• not implemented

Demo

Import the following code modules:

• Demo.bas - run DemoMain
• DemoTimer.cls

There is also a Demo Workbook available for download.