Custom module: Dynamic logic

Settings are usually not dynamic, by their nature they are things that are "set", you may want to leverage a macro method instead that gets the value based on some conditions. Can you outline what dynamic logic you are looking to accomplish?

If the value that is dynamic is a custom setting then you should be able to call the API to update that setting key during your custom event. It's not impossible but as Trevor stated, it's not a common practice.

Bk is right that you can use the API to set a new value, is that what you are trying to do? I read it you want the setting itself to be a dynamic value, which it doesn't support. But there may be other options depending on what you are trying to accomplish.