Why does the assign method fire when a property with an assign method is used in a math expression on the right side of an assignment statement? This happens in VFP 6 and 7.

DEFINE CLASS MyCLASS as Custom
	PROCEDURE height_assign
		LPARAMETERS vNewVal
		*To do: Modify this routine for the Assign method
		THIS.Height = m.vNewVal
		WAIT WINDOW "Assignment fired - value "+ STR(vnewval)+".  Press any key to continue.."
	ENDPROC
ENDDEFINE

* Test program to show anomally
PROCEDURE test

* create class
o = CREATEOBJECT("myclass")
* Wait window should appear in assign method
o.height = 1
* wait window should not appear in assign method
y= o.height+2

Return