2009/10/6 章宏九 <secludeds...@gmail.com>:
> Thank you. I saw all the examples you gave, but I still cannot master
> how to use a variant record without a specified tag.
>
> For example:
> type
> TShapeList = (Rectangle, Triangle, Circle, Ellipse, Other);
> TFigure = record
> case TShapeList of
> Rectangle: (Height, Width: Real);
> Triangle: (Side1, Side2, Angle: Real);
> Circle: (Radius: Real);
> Ellipse, Other: ();
> end;
> var
> Figure1: TFigure;
>
> How can I specified the TShapelist value in a Figure1?
You can specify an identifier in the case statement, which will become
a new field. You can then specify what the record is used for
currently, e.g.:
TShapeList = (Rectangle, Triangle, Circle, Ellipse, Other);
TFigure = record
case Shape: TShapeList of
^^^^^^^
Rectangle: (Height, Width: Real);
Triangle: (Side1, Side2, Angle: Real);
Circle: (Radius: Real);
Ellipse, Other: ();
end;
Then you can set .Shape to Rectangle, for instance, and fill in
.Height and .Width. A function receiving a variable of this record
can then see what shape it is currently used for. You need to
maintain this .Shape field, though.
Henry
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