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(* Library module defined by the International Standard
Information technology - programming languages
BS ISO/IEC 10514-1:1996E Part 1: Modula-2, Base Language.
Copyright ISO/IEC (International Organization for Standardization
and International Electrotechnical Commission) 1996-2021.
It may be freely copied for the purpose of implementation (see page
707 of the Information technology - Programming languages Part 1:
Modula-2, Base Language. BS ISO/IEC 10514-1:1996). *)
DEFINITION MODULE StdChans;
(* Access to standard and default channels *)
IMPORT IOChan;
TYPE
ChanId = IOChan.ChanId;
(* Values of this type are used to identify channels *)
(* The following functions return the standard channel values.
These channels cannot be closed.
*)
PROCEDURE StdInChan (): ChanId;
(* Returns the identity of the implementation-defined standard source for
program
input.
*)
PROCEDURE StdOutChan (): ChanId;
(* Returns the identity of the implementation-defined standard source for program
output.
*)
PROCEDURE StdErrChan (): ChanId;
(* Returns the identity of the implementation-defined standard destination for program
error messages.
*)
PROCEDURE NullChan (): ChanId;
(* Returns the identity of a channel open to the null device. *)
(* The following functions return the default channel values *)
PROCEDURE InChan (): ChanId;
(* Returns the identity of the current default input channel. *)
PROCEDURE OutChan (): ChanId;
(* Returns the identity of the current default output channel. *)
PROCEDURE ErrChan (): ChanId;
(* Returns the identity of the current default error message channel. *)
(* The following procedures allow for redirection of the default channels *)
PROCEDURE SetInChan (cid: ChanId);
(* Sets the current default input channel to that identified by cid. *)
PROCEDURE SetOutChan (cid: ChanId);
(* Sets the current default output channel to that identified by cid. *)
PROCEDURE SetErrChan (cid: ChanId);
(* Sets the current default error channel to that identified by cid. *)
END StdChans.
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