EXEC_ON_SELECT Procedure (Unix)

Registers callback procedures on input for a vector of logical unit numbers (LUNs).

This function will not work when a PV‑WAVE Widget application is running. This is due to an interaction between the event loop and the PV‑WAVE facility used to detect input on a file descriptor.

Usage

    EXEC_ON_SELECT, luns, commands

Input Parameters

luns—Vector of logical unit numbers.

commands—Vector of procedure names. It must have the same number of entries as the vector luns.

Keywords

Widget—If present and nonzero, resisters LUNs and commands with the WAVE Widgets or Widget Toolbox event loop (WwLoop or WtLoop).

Just_reg—If present and nonzero, registers the unit numbers and callback procedures. Do not wait for any input. This is useful when this procedure is used with widgets.

Discussion

This procedure checks for input on all the logical unit numbers specified in the luns vector. When there is input available on luns (k), the commands (k) procedure is called with luns (k) as its (only) argument. This procedure never returns; it just keeps handling callbacks when input is available.

When used with the WAVE Widgets applications (i.e., when the Widget and Just_reg keywords are used), the callback procedures must have the following parameters:

top, data, nparams, id, lun, source

See Also

ADD_EXEC_ON_SELECT, DROP_EXEC_ON_SELECT, SELECT_READ_LUN