Is there a way to parameterize functions in COBOL?

Question

I'm coding routines like:

READ-A.
       READ FILE-A
           AT END
             MOVE 1 TO EOF-A
           NOT AT END 
             ADD 1 TO CN-READ-A
       END-READ.
F-READ-A. EXIT.

to read several files and I was wondering if there's a way to code a routine that is able to read the filename from a variable so I don't have to code the same thing for each file. Thanks!

Answer 1

One solution as said above is to use multiple programs or nested program, for which I have included an example below, which is solution 1.

Another solution is to COBOL classes, which might not be to your liking but I like them, so I've included an example, which is solution 2.

Solution 1:

   program-id. TestProgram.
   working-storage section.
   01 file-name        pic x(128).
   01 file-lines       pic 9(9).
   procedure division.
       move 0 to file-lines
       move "d:\rts_win32.txt" to file-name
       call "program1" using file-name file-lines
       display file-lines
       stop run
   end program TestProgram.

   program-id. Program1.

   file-control.
       select file-a assign to myfile
           organization is line sequential.

   data division.
   fd file-a.
   01 file-a-line      pic x(80).

   working-storage section.
   01 EOF-A            pic 9 value 0.
   linkage section.
   01 lk-filename      pic x(128).
   01 CN-READ-A        pic 9(9).
   procedure division using lk-filename
                            CN-READ-A.

       move lk-filename to myfile
       open input file-a

       perform READ-A until EOF-A equals 1
       close file-a
       goback.

       READ-A.
       READ FILE-A
           AT END
             MOVE 1 TO EOF-A
           NOT AT END 
             ADD 1 TO CN-READ-A
       END-READ.
       F-READ-A. 
       EXIT.


   end program Program1.

Solution 2

  program-id. TestProgram.:
   working-storage section.
   01 file-counter type FileLineCounter.

   procedure division.
       set file-counter to new type FileLineCounter("d:\rts_win32.txt")
       display file-counter::LineCount
       stop run
   end program TestProgram.

   class-id FileLineCounter.

   file-control.
       select file-a assign to myfile
           organization is line sequential.

   data division.
   fd file-a.
   01 file-a-line      pic x(80).

   working-storage section.

   01 cn-read-a binary-long property as "LineCount".

   method-id New.
   01 EOF-A            pic 9 value 0.
   procedure division using by value filename as string.

       set myfile to filename
       open input file-a

       perform READ-A until EOF-A equals 1
       close file-a
       goback.

       READ-A.
       READ FILE-A
           AT END
             MOVE 1 TO EOF-A
           NOT AT END 
             ADD 1 TO CN-READ-A
       END-READ.
       F-READ-A. 
       EXIT.

   end method.

   end class.