How to use default component value as variable in assignin()

I've added components to an app and set default values for some of them. How does one access these default values in order to use them in assignin() such that it is unnecessary to change them or write over them in the UI?

[dpb]

Think we'll have to see some code to illustrate what, specifically, you're talking about...I've set default values on UI in app's and never run across a need for assignin so having hard time imagining what you must be trying to do here.