Conditional block instantiation within GRC

I have GRC-based flowgraph where I’d like to be able to turn off the
graphical blocks, to save CPU.
Ideally, I’d like to be able to pass a command-line parameter that
controls whether certain blocks
are instantiated and connected into the flow-graph.

I know there’s a “disable” mechanism within GRC itself, but is there any
way to do that dynamically
when the flowgraph starts?

Principal Investigator
Shirleys Bay Radio Astronomy Consortium