[Discuss-gnuradio] Stream selector and changing variable after N samples

[Aylons Hazzud]

I have been experimenting with the stream selector in gnuradio
companion, but am stuck in situation.

First, how do I change a variable after N samples? I want the signal
to switch from a filter to another at a fixed rate, but blks2.selector
uses a variable to do the switching.

So, how could I change the value of this variable after N samples?

Am I missing any documentation on using variables to dynamically
change block behaviour? Looks like gr-extras is full of these
situations, but I can't find documentation on how to use it.