Maybe something like this (?):
[some operations] doWithPrecision: 100.
Precision is thread-variable (Thread current precisionOf Floats).
Tempting, but that doesn't handle the case that you call back into another module -- the other module will get your module's floating point precision. I guess we could posit yet a new kind of variable whith is thread-specific *and* module specific....
If that module needs specific precision, it will setup own precision of floats at entry point and restore original precision on exit. This is how works proposed
[some operations] doWithPrecision: 100
If the module does not need specific precision, everything is OK.
Viktor