[PD] setting variables within an if condition in [expr] or [fexpr~]

[Peter Worth]

the algorithm i'm trying to implement using fexpr~ requires some kind
of variable, to store whether it's current output is on or off (1 or
0) - it needs to act differently in each case. ideally i'd like to
simply put the output back into another input so i can just query its
current state, but obviously this causes dsp loop errors, and i cant
use send~ and recieve~ to do this because it delays it by a block, so
on a sample by sample basis its completely out of date by the time it
comes back as one of the inputs..

so i'm guessing i need to use a variable or [value]. but can i set
this within an fexpr~ object, and will it update fast enough (if it
takes a block to update then its no good).

any ideas?

thanks.