latest method
The mark added last, for a caller that built one and let go of it.
A chart with no marks answers a mark belonging to nothing and reports it in
errors, rather than quietly adding a point nobody asked for.
Returns The last mark added.
Implementation
VlChartMark latest() {
int n = marks.length;
if ( n > 0 ) {
return marks[(n - 1)];
}
this.error("the chart has no marks, so there is no last one");
VlChartMark loose = VlChartMark();
loose.owner = this;
return loose;
}