User interface

GIPSY programs do not interact with the user directly, but do this through the GIPSY user interface, Hermes. If for instance a program needs some input from the user, it will send a request to Hermes which will then prompt the user for the required parameters. The same goes for informational messages intended for the user. If a program wants to inform the user that the integrated flux density of a source is x Janskys, it will not do this with an ordinary WRITE statement, but via a library routine which sends a request to Hermes.

Below is an overview of the most important user interface facilities. Documentation of all user interface routines can be found in a separate document. There is also an example program which demonstrates the use these routines.

Starting and stopping

The first thing a task must do when it is running is to tell Hermes that it is alive and ready for communication. This is done with subroutine INIT. A call to INIT must always be the first executable statement in a task.
Likewise we need to inform Hermes that the task has finished its job. This is done with a call to FINIS (always just before the STOP or END statement).

User input

Input from the user is requested with the USERxxx routines. There are eight of those routines, each for different types of inputs.
requests INTEGER input
requests LOGICAL input
requests REAL input
requests DOUBLE PRECISION input
requests CHARACTER input
same as USERCHAR, but all characters are converted to lower case
same as USERCHAR, but all characters are converted to upper case
requests verbatim CHARACTER input
All these routines are integer functions which return the number of items entered by the user. Arguments to these routines are: Default levels have the following effect:
0 --- no default is possible
1 --- user is prompted, but default is taken when user types RETURN
2 --- user is not prompted and default is taken unless the input was pre-specified
4 --- (added to any of the above values) the user is required to enter the exact number of items

The behaviour of GIPSY resulting from a call to these routines is described in the user documentation.

User input keywords

When one of the user input routines is called, the user may be prompted depending on the value of the default level and whether the requested keyword is already known to Hermes. So repeated calls for the same keyword do not automatically prompt the user, but normally return the value that is already present.

Cancelling a keyword

If it is necessary to prompt the user again for some keyword, e.g. when the task executes a loop and for every pass through the loop a new value is required, the routine CANCEL should be called.

Rejecting a keyword

Before the input given by the user is passed to the task, Hermes checks if it conforms to the task's request. If not, Hermes rejects the input and prompts the user again.
If the input does conform to the request, but for an other reason is unacceptable to the task, the task can call the routine REJECT and then request the input again. One of the arguments to REJECT is a message intended to explain why the input is unacceptable. This message will be displayed in tHermes' User Command Area.

Text output

Tasks can send output to the terminal screen and/or the log file using the subroutine ANYOUT. Arguments to this routine are:

Status output

Information about the status of a atsk, i.e. what the task is doing at the moment, can be sent to Hermes' Task Status Area using the subroutine STATUS. This routine has one argument: a character constant or variable containing the status message.

Error reporting

A task can report any errors it encounters by calling the subroutine ERROR. Arguments to this routine are:

More features...

A separate document lists all user interface routines. Routines not described above support following features:
Programming GIPSY