›MODULE ; CATCH.ACT››; copyright (c) 1984›; by Action Computer Services›; All Rights Reserved››; This module provides two PROCs›; (Catch and Throw) which can be used›; for error trapping (and flow›; control, yeck!) in ACTION!.  To›; use them, you must call the Catch›; PROC to indicate where you want›; the program to continue when you›; call Throw.  When throw is called,›; execution will continue following›; the last call to Catch with the›; same index as the call to Throw.›; Calling Catch is similar (but not›; identical) to TRAP in BASIC.  It›; differs in that the actual trapping›; is generated by the user (by›; calling Throw) and that you can›; have multiple Catch'ers active at›; one time.  Also, you cannot Throw›; to a Catcher that is no longer ›; active (the PROC/FUNC containing›; it has RETURN to it's caller).  The›; Throw procedure tries to check for›; this error, but it is possible to›; fool it into thinking it's OK.  If›; you want to solve this problem, you›; can set 'c_t_sp(index)' to zero›; before you return from the PROC›; that contained the Catch(index).›; If index is greater than 24 or›; if there is no matching Catch index›; for the Throw, then Error will be›; called with a value of CTERR›; (defined below to be 71).  If you›; setup your own Error procedure and›; use Catch and Throw, your error›; procedure should handle this error›; as well or your program will most›; likely "go off the deep end".›››DEFINE CTERR = "71" ››BYTE ARRAY c_t_sp(25)=[0 0 0 0 0 0 0› 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]›BYTE ARRAY c_t_hi(25), c_t_lo(25)›››PROC Catch(BYTE index)›  DEFINE TSX="$BA", TXA="$8A",›         LDYA="$AC", STAY="$99",›         PLA="$68", LDAY="$B9",›         PHA="$48"››  IF index>=25 THEN›    Error(CTERR,0,CTERR) FI ››  [›    LDYA index  ›    PLA›    STAY c_t_hi›    PLA›    STAY c_t_lo›    TSX›    TXA›    STAY c_t_sp›    LDAY c_t_lo›    PHA›    LDAY c_t_hi›    PHA›  ]›RETURN›››PROC Throw(BYTE index)›  DEFINE TXS="$9A", PHA="$48",›         LDYA="$AC", STX="$86",›         TSX="$BA", TAX="$AA",›         LDAY="$B9"››  BYTE sp=$A2››; get current stack pointer›  [ TSX : STX sp ]››  IF index>=25 OR sp+2>c_t_sp(index)›    THEN Error(CTERR,0,CTERR) FI ››  [›    LDYA index  ›    LDAY c_t_sp›    TAX›    TXS›    LDAY c_t_lo›    PHA›    LDAY c_t_hi›    PHA›  ]›RETURN››MODULE ; just in case››