  The problem of the calculation of inclusive breakup cross sections in nuclear
reactions is reexamined. For that purpose, the post-form theory proposed by
Ichimura, Austern and Vincent [Phys. Rev. C32, 431 (1985) is revisited, and an
alternative derivation of the non-elastic breakup part of the inclusive breakup
is presented, making use of the coupled-channels optical theorem. Using the
DWBA version of this model, several applications to deuteron and $^6$Li
reactions are presented and compared with available data. The validity of the
zero-range approximation of the DWBA formula is also investigated by comparing
zero-range with full finite-range calculations.
