  We construct a patchy feedback for a general control system on $\R^n$ which
realizes practical stabilization to a target set $\Sigma$, when the dynamics is
constrained to a given set of states $S$. The main result is that
$S$--constrained asymptotically controllability to $\Sigma$ implies the
existence of a discontinuous practically stabilizing feedback. Such a feedback
can be constructed in "patchy" form, a particular class of piecewise smooth
controls which ensure the existence of local Carath\'eodory solutions to any
Cauchy problem of the control system and which enjoy good robustness properties
with respect to both measurement errors and external disturbances.
