Page History

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
     EXECUTE SUBROUTINE(GET_FILE)
...
 WITH_PARMS(
...
#KEY1 ...
...
 #KEYn)
...
The actual "demand" subroutine in generalized format would look like this:SUBROUTINE NAME
     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).