Constructing a nested shadowop call

This page applies to Harlequin v13.1r0 and later; both Harlequin Core and Harlequin MultiRIP.

This nested shadowop call checks whether an operator (in this case setscreen) has been shadowed before, and makes sure that it calls the previous shadow if so.

TEXT

            <<
              /setscreen {
                          {
                          (setscreen angle: )print 1 index ==
                        } exec
                        { setscreen } exec
              }
              1183615869 internaldict /shadowproc get /setscreen
              2 copy known {
                    get dup null ne {
                                      % proc oldproc
                                      2 copy 2 exch put pop
                    } { pop } ifelse
              } { pop pop } ifelse bind
            >> 1183615869 internaldict /shadowop get exec