Summary of GT.M Error-Handling Facilities

EXTENSION

EXPLANATION

OPEN/USE/CLOSE EXCEPTION

Provides a deviceparameter specifying an XECUTE string or entryref that GT.M invokes upon encountering a device-related exception condition.

MUMPS /LIST ZLINK :"/LIST"

Creates a listing file of all the errors detected by the compiler. Detects syntax errors. Useful in the process of re-editing program to correct errors.

ZGOTO

Provides for removing multiple levels from the M invocation stack.

ZMESSAGE

Creates or emulates arbitrary errors.

$STACK

Contains the current level of M execution stack depth.

$STACK()

Returns values describing aspects of the execution environment.

$ECODE

Contains a list of error codes for “active” errors; these are the errors that have occurred, but have not yet been cleared.

$ESTACK

Contains an integer count of M virtual machine stack levels that have been activated and not removed, since the last time $ESTACK was NEW'd.

$ETRAP

Contains a string value that GT.M invokes when an error occurs during routine execution.

$QUIT

Indicates whether the current block of code was called as an extrinsic function or a subroutine.

$ZCSTATUS

Holds the value of the status code for the last compilation performed by a ZCOMPILE command.

$ZEDIT

Holds the value of the status code for the last edit session invoked by a ZEDIT command.

$ZEOF

Holds the value ‘1’ (TRUE) if the last READ on the current device reached end-of-file, otherwise holds a ‘0’ (FALSE).

$ZERROR

Contains a string supplied by the application, typically one generated by the code specified in $ZYERROR.

$ZLEVEL

Contains current level of DO/EXECUTE nesting ($STACK+1).

$ZMESSAGE()

Translates a VMS/GT.M condition code into text form.

$ZSTATUS

Contains the error condition code and location of last exception condition occurring during routine execution.

$ZTRAP

Contains an XECUTE string or entryref that GT.M invokes upon encountering an exception condition.

$ZYERROR

Contains an entryref to invoke when an error occurs; typically used to maintain $ZERROR.