REM Module load error handler.
REM Run by !Run. Usage is as follows...
REM To check RISC-OS 3 or better...

REM RMEnsure UtilityModule 3.00 Run <Obey$Dir>.Error <CLI Opts>

REM To change the dialog box title use. : -a"<AppName>".
REM The message is set using switch.    : -m"<Some Message>"

REM <Obey$Dir>.Error Points to this file. Normal conditions for
REM use of SYS"Wimp_ReportError" apply to this.

program$="Error Handler":q$=CHR$(34)
msg$="v1.01 Syntax : -a"+q$+"<Appname>"+q$+" -m"+q$+"<Message>"+q$

REM ***** LibCLI Embedded portion. *****

REM Grab our CLI and process it.
i%=0                               :REM Init our counter.
SYS "OS_GetEnv" TO c$              :REM Grab CLI.
c$=FNcli_getswitch(c$)             :REM Strip out our filespec.

REPEAT                             :REM ** Process command line.
 switch$=FNcli_extract(c$)         :REM Extract a switch.
 opt$=LEFT$(switch$,2)             :REM Get first 2 chars.

 REM Check against known switches and set program values.
 CASE opt$ OF
  WHEN "-a","-A":program$=FNcli_grabquoted(switch$)
  WHEN "-m","-M":msg$=FNcli_grabquoted(switch$)
 ENDCASE

 REM Increment counter. If this is still zero when c$="" then we
 REM haven't been given any switches.
 i%+=1
UNTIL c$=""     :REM Wash... Rinse... Repeat...
REM ***** End of LibCLI Embedded portion. *****

DIM Block 256:Block!0=1234:$(Block+4)=msg$+CHR$0
SYS "Wimp_ReportError",Block,17,program$
END

REM Return just the "switch-line."
REM c$    : Command line to parse...
REM t$    : Temporary store for output...
REM i%    : Loop counter...
REM p%    : Position of the first switch in the string...
REM q%    : If q%=2 then we return the rest of the line...
REM Always ignore the first instance (BASIC -quit <filespec>)
DEFFNcli_getswitch(c$)
 LOCAL i%,p%,q%,t$
 i%=0:p%=0:q%=0
 FOR i%=1 TO LEN(c$)
  IF ASC(MID$(c$,i%,1))=34 THEN
   q%+=1
   IF q%=2 THEN p%=i%
  ENDIF
 NEXT i%
 t$=RIGHT$(c$,LEN(c$)-p%)
 IF LEFT$(t$,1)=" " THEN =RIGHT$(t$,LEN(t$)-1)
=t$

REM Extract a parameter from the command line...
REM c$    : Command line to parse...
REM out$  : Extracted parameter...
REM s%    : Position in the string of the first switch...
REM ns%   : Position in the string of the next switch...
REM We subtract s% from ns% to get the length of the parameter to
REM return. This starts at position s%. Finally we remove the
REM parameter we've just found from the command line.
DEFFNcli_extract(RETURN c$)
 LOCAL t$,s%,ns%,out$
 s%=INSTR(c$,"-"):ns%=INSTR(c$,"-",s%+1)
 out$=MID$(c$,s%,ns%-s%):c$=RIGHT$(c$,LEN(c$)-(ns%-1))
 IF c$=out$ THEN c$="" :REM We've just extracted the last one...
 IF RIGHT$(out$,1)=CHR$(32) THEN =LEFT$(out$,LEN(out$)-1)
=out$

REM Extract a quoted string from a parameter.
REM p$    : Parameter to parse...
REM t$    : Temporary store for string...
REM oq%   : Position in the string of the first (open) quote.
REM cq%   : Position in the string of the second (close) quote.
REM l%    : Length of the string inside the quotes.
REM This allows us to use "-" characters in filenames by enclosing
REM filespecs in quotes and ignoring "-" that appear in quotes.
DEFFNcli_grabquoted(p$)
 LOCAL t$,oq%,cq%,l%
 oq%=INSTR(p$,CHR$(34)):l%=0
 IF oq%<>0 THEN
  cq%=INSTR(p$,CHR$(34),oq%+1)
  IF cq%<>0 THEN l%=(cq%-oq%)-1
 ENDIF
 IF l%=0 THEN =""
=MID$(p$,oq%+1,l%)