execute_segment(3G)

NAME

execute_segment − add a segment execution element into the open segment

SYNOPSIS

C Syntax:

void execute_segment(fildes, segno)
int fildes, segno;

FORTRAN77 Syntax:

subroutine execute_segment(fildes, segno)
integer*4 fildes, segno

Pascal Syntax:

procedure execute_segment(fildes, segno:integer);

DESCRIPTION

Input Parameters

fildes Integer file descriptor returned by gopen when an I/O path to a graphics device is opened.

segno Name of the executed segment. This can be any integer value.

Discussion

Execute_segment adds a segment reference element to the open segment. When the execute segment element is encountered during a traversal, a subset of the current Starbase state is saved (see push_state(3G)), the segment with name segno is traversed, the Starbase state is restored (see pop_state(3G)) and the traversal continues with the next element.

Execute_segment(3G) only differs from call_segment(3G) in the implicit state save and restore at traversal time.

The referenced segment, segno, does not need to exist prior to invocation of execute_segment. An empty segment will be created if necessary to satisfy the reference.

EXAMPLE

In the following C program segment, fildes is assumed to hold a file descriptor returned by a call to gopen(3G). Segment 2 is referenced from segment 1. The change to line_color_index in segment 2 will not affect the color of the polylines in segment 1, due to the implicit state save and restore.

open_segment(fildes,1,FALSE,FALSE); /* build segment 1 */
line_color_index(fildes, 1);/* set line color to index 1 */
polyline(fd, ...);/* polyline drawn in color 1 */
execute_segment(fildes, 2);/* invoke segment 2 here */
polyline(fd, ...);/* polyline drawn in color 1 */
close_segment(fildes);/* segment 1 is now closed */
open_segment(fildes,2,FALSE,FALSE); /* build segment 2 */
line_color_index(fildes,3);/* set line color index to 3 */
polyline(fd, ...);/* polyline drawn in color 3 */
close_segment(fildes);/* segment 2 is now closed */

ERRORS

1 Graphics device is not initialized for this operation.

24 Segment not open.

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