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Jeff, Is there any limit to the number of times that a subroutine in a command procedure can be called? I'll be crushed if there is, because I much prefer them to wretched GOTOs. I also heard that they're fast, too. |
In answer to your question "Is there any
limit to the number of times that a subroutine in a command
procedure can be called?" the answer is : There is no limit. However DCL is not reentrant so a
procedure cannot call itself, or call another procedure that
eventually calls itself again. Also for any given level of
DCL command procedures, GOSUB calls can only go 16 levels
deep in calls. Hope this helps Jeff PS. I am an old FORTRAN programmer,
competent in my skills as such, and I'm not afraid to use
GOTOs.
Addendum
2-JUN-1999
Thanks to Brian
Schenkenberger of TMESIS for
pointing out that the proper answer is a bit more involved
than the above response. In DCL there are two types of
SUBROUTINES. There is the GOSUB/RETURN version and the
CALL/SUBROUTINE/ENDSUBROUTINE version. In my answer above I was only addressing
the GOSUB/RETURN version, where you are allowed 16 levels of
subroutine calls for each of the possible 32 DCL command
procedure levels. This form is not reentrant since the
context of local DCL symbols is valid only for the level of
the command procedure, and all GOSUB levels use the same
scope of local and global DCL symbols. As Brian pointed out to me, the other
method of DCL subroutines, ie: the
CALL/SUBROUTINE/ENDSUBROUTINE method, essentially allows the
user to encapsulate a multiple file/command procedure into
one file/command procedure. In other words rather than
having multiple command procedures calling one another using
the @ (at-sign) they could invoke the procedure using the
DCL CALL command which then processes the corresponding
SUBROUTINE/ENDSUBROUTINE section as if it were a new level
of DCL command procedures, even though the code is embedded
in the original file/command procedure. In this case, you are limited by DCL's
level of command procedures, ie: 32 levels. Also, since each
level of DCL command procedures allows a local DCL symbol
table, you can say that this form of DCL subroutine calls is
indeed, reentrant, as long as you do not exceed the total
procedure level of 32.
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