The "demand" subroutines described in the previous examples can be generalized and used for any file.
Consider a "generalized" FETCH command like this:
FETCH FIELDS(#FIELD1 #FIELD2 ... #FIELDn) FROM_FILE(FILE)
WITH_KEY(#KEY1 ... #KEYn)
This can be replaced by executing a "demand" subroutine that exactly emulates the FETCH command like this:
EXECUTE SUBROUTINE(GET_FILE) WITH_PARMS(#KEY1 ... #KEYn)
The actual "demand" subroutine in generalized format would look like this:
SUBROUTINE NAME(GET_FILE) PARMS((#GETKEY1 *RECEIVED)
" "
(#GETKEYn *RECEIVED))
DEFINE FIELD(#GETKEY1) REFFLD(#KEY1)
" " " "
DEFINE FIELD(#GETKEYn) REFFLD(#KEYn)
DEF_LIST NAME(#FILE)
FIELDS(#KEY1 ... #KEYn #FIELD1 ... #FIELDn)
TYPE(*WORKING) ENTRYS(as required)
LOC_ENTRY IN_LIST(#FILE) WHERE('(#KEY1 = #GETKEY1) *AND
" " "
(#KEYn = #GETKEYn)')
IF_STATUS IS_NOT(*OKAY)
FETCH FIELDS(#FIELD1 #FIELD2 ... #FIELDn) FROM_FILE(FILE)
WITH_KEY(#GETKEY1 ... #GETKEYn)
ADD_ENTRY TO_LIST(#FILE)
ENDIF
Points to Note:
- This routine does not account for 2 possibilities.
- The first is that the working list may overflow. This could be solved by using the COUNTER parameter on the DEF_LIST command. Before the ADD_ENTRY command the value could be checked and the list cleared (CLR_LIST command) if greater than or equal to the ENTRYS value.
- The second is the fact that the requested record may not be found in either the working list or the database. This could be solved by an IF_STATUS after the FETCH command. If found the record would be added to the working list. If not found appropriate action could be taken (e.g.: ABORT command).