I would think this will arrive sooner or later in the core Qlik Sense Enterprise product, but not wanting to wait I created an alternate solution for this. It solves my needs in this space but there are of course room for improvement too.
The solution is built around a generic key-value store, which is included in recent versions of the open source Butler service (butler.ptarmiganlabs.com).
The idea is pretty simple:
You first insert into the key-value store whatever parameters you want to pass to a an app's load script. This is done by calling Butler's REST API, either using some 3rd party tool outside of Sense (database, upstream data source, Powershell etc) or from another Sense app using a "Call AddKeyValue()" call.
The second app then reads the keys where parameters are stored, and voila - we have parameter passing between apps as well as from outside world into an app.
Like this:
True, you will have to set up and run Butler for this to work. But it's open source (free) and runs nicely even on the existing Sense servers. You also need to add some script lines for inserting the parameters, but it's literally just a few lines of script:
Write values to key-value store from the first app...
Every single workaround I saw so far (including the suggestion for Butler above) has one fatal flaw: they are scoped to the app, not to the task. There is just no way to have 1 app
So if previously you had 1 app and a task that was spitting out 10 versions based on a parameter with 10 values, or 1 app with multiple tasks specified and parametrized differently, suddenly you need 10 apps. If all the app was doing was data processing, then it's not so bad, you can minimize repetition of script via includes. If the app had actual visualizations in it... ouch.
Yes please, this is such a useful feature for reload workflow flexibility.
My current use case: designing a workflow for daily extracts and weekly extracts behaving differently. I'd like to "flip a variable switch" to force different processing behavior on the weekend.