protect deRegUserTriggers, drLoadDrf, etc

background:

cdsinit is loaded by more than just virtuoso.  ocean, runams, and others will load it.  Some functions don't make sense in all environments.  For example

deRegUserTriggers("maskLayoutXL" ...)

doesn't make sense for runams (app is not known).  I've protected my trigger registration with things like

when(deGetAppInfo("maskLayoutXL")
  deRegUserTriggers("maskLayoutXL" nil 'my_trigger_fn nil)
)

I've also used isCallable('someFunction) in a few spots.

Is this the right way to protect against calling some of this code in the wrong tool?  Another that I don't have a good answer for is drLoadDrf().  If runams encounters that it throws this error:

*Error* apply: undefined function - _ciInitDisplayPackets

so I could use isCallable('_ciInitDisplayPackets) but I don't like checking a private function because it may just suddenly break my code.  Any other good ways to protect drLoadDrf()?

Another one I'm getting I think is from a call to ciwMenuInit():

*WARNING* ciwMenuLoadFile: system file "/opt/eda/cadence/IC617/tools.lnx86/dfII/etc/tools/menus/runams.menus" not found.

Thanks

-Dan