  We study the generalized hydrodynamics of the one-dimensional classical Non
Linear Schroedinger equation in the attractive phase. We thereby show that the
thermodynamic limit is entirely captured by solitonic modes and radiation is
absent. Our results are derived by considering the semiclassical limit of the
quantum Bose gas, where the Planck constant has a key role as a regulator of
the classical soliton gas. We use our result to study adiabatic interaction
changes from the repulsive to the attractive phase, observing soliton
production and obtaining exact analytical results which are in excellent
agreement with Monte Carlo simulations.
