RE: GOBACK vs EXIT PROGRAM

[geir.kildal@xxxxxxxxxxxxxx]

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.
.
Jon.

Thank you for a thorough explanation.  So we can just forget EXIT
PROGRAM/STOP RUN and only  use GOBACK, then, in all programs, without
considering whether they are called as main- or subprograms (or both)?


Mvh.

Geir Kildal






"Jon Paris" <Jon.Paris@Partner400.com>
Sent by: cobol400-l-admin@midrange.com
03.05.2002 18:01
Please respond to cobol400-l


        To:     <cobol400-l@midrange.com>
        cc:
        Subject:        RE: GOBACK vs EXIT PROGRAM


 >> please explain the difference between GOBACK and EXIT PROGRAM for
me(and
maybe a lot of others?)

GOBACK was added in ANSI '85 (I think) as an answer to the age-old problem
caused by the fact that EXIT PROGRAM is ignored when in the main program.
It is just a no-op and cause the logic to drop-though to whatever is next
in
the code.  Nasty and produces some very hard to debug situations.  This
causes problems in a multi-language environment where a generic routine
may
be called form COBOL as a sub program or from another language, in which
case it would tend to become main.  In many cases programs would be coded
as
EXIT PROGRAM followed by STOP RUN on the next line to avoid dropping
through
into unexpected logic.  Alternatively in implementations that allowed
non-COBOL programs to appear within the run unit (such as the OS/400 COBOL
implementations) a "stub" program is often used in front of the non-COBOL
programs to ensure that any subsequent COBOL programs are sub programs.
This has the added benefit of increasing performance as the run unit is
not
constantly being torn down and then rebuilt.

GOBACK was the "solution" since they couldn't change the definition of
EXIT
PROGRAM.  GOBACK acts as an EXIT PROGRAM in a sub program and STOP RUN if
it
is in a main.

Jon Paris
Partner400


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