☜	USE Draft MDC Standard					☞

8.2.36 Use

U[SE] postcond SP L useargument

There is a large overlap in specification between the commands Open, Use, and Close. As a side-effect of the alphabetical ordering of the commands, many features are described in clause 8.2.6, the Close command. As a matter of style in this document, these features are not repeated in this clause.

Before a device can be employed in conjunction with an input or output data transfer it must be designated, through execution of a Use command, as the current device. Before a device can be named in an executed useargument, its ownership must have been established through execution of an Open command. See 8..2.7 for the syntax and interpretation of devn and deviceparameters.

The specified device remains current until such time as a new Use command is executed. As a side effect of employing expr to designate a current device, $IO is given the value of expr contained in devn and $IOReference is given the value of devn. See 7.1.4.10.6 and 7.1.4.10.7 for any differences between $IO and $IOReference.

Specification of device parameters, by means of the exprs in deviceparameters, is normally associated with the process of obtaining ownership; however, it is possible, by execution of a Use command, to change the parameters of a device previously obtained.

Distinct values for $X and $Y are retained for each device. The special variables $X and $Y reflect those values for the current device. When the identity of the current device is changed as a result of the execution of a Use command, the values of $X and $Y are saved, and the values associated with the new current device are then the values of $X and $Y.

Copyright © Standard Documents; 1977-2024 MUMPS Development Committee;
Copyright © Examples: 1995-2024 Ed de Moel;
Copyright © Annotations: 2003-2008 Jacquard Systems Research
Copyright © Annotations: 2008-2024 Ed de Moel.

Some specifications are "approved for inclusion in a future standard". Note that the MUMPS Development Committee cannot guarantee that such future standards will indeed be published.

This page most recently updated on 08-Jan-2024, 12:14:37.

For comments, contact Ed de Moel (demoel@jacquardsystems.com)