From:	CSBVAX::CSBVAX::MRGATE::"SMTP::CRVAX.SRI.COM::RELAY-INFO-VAX" 23-FEB-1989 17:51
To:	MRGATE::"ARISIA::EVERHART"
Subj:	DCL bug...


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Date:     Thu, 23 Feb 89 10:57 EDT
From:     <B_COSTA%UNHH.BITNET@MITVMA.MIT.EDU>
Subject:  DCL bug...
To:       info-vax@kl.sri.com
X-Original-To:  info-vax@kl.sri.com, B_COSTA


    An interesting bug has recently been discovered in DCL which we have
    confirmed exists in our version 5.0-2 (and Colorado's 5.1) of VMS.  The
    following DCL command procedure causes an error from which DCL cannot
    recover; the process is thus forced to exit - in effect - logging it
    off.

$  ON ERROR THEN GOTO Abort             ! Action to take on any error...
$
$ TestP1:       IF (P1 .NES. "")
$                         WRITE SYS$OUTPUT "P1 = <''P1'>"
$                    ELSE WRITE SYS$OUTPUT "First parameter required."
$               ENDIF
$
$ End:          EXIT
$
$ Abort:        WRITE SYS$OUTPUT "% Procedure aborted..."
$               EXIT
$

    The "IF" statement is wrong; the "THEN" is missing.  This of course
    causes the DCL error:

%DCL-E-INVIFNEST, invalid IF-THEN-ELSE nesting structure or data inconsistency

    Normally this shouldn't be a serious problem. However, the combination
    of this error and an "ON WARNING" or "ON ERROR" statement like the one
    above results in an "Improperly handled condition" and *poof* -- no
    process!

    In the final analysis, this is more of an inconvenience than anything
    else; if your command procedure has what amounts to a syntax error -
    you probably don't want it to run anyways - it's just annoying to get
    blown off the system too!  Of course it does mean that if you have a
    big job that calls other procedures, and one of these procedures has
    such an error - the caller does not have a prayer of recovering in any
    way.

                                                                BC


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