怎么才能让自定义属性对用户只读
如题，如何设置属性对用户只读？而程序可以改变它的值？用protect和hidden关键词的话，用户也无法访问这个属性了。。。
程序代码：
clea
otest=CREATEOBJECT('employee')
otest.hiredate={^2022-12-01}
?otest.hiredate
otest.sethiredate()
?otest.hiredate
DEFINE CLASS employee AS CUSTOM
*!* HIDDEN HireDate
*!* PROTECTED HireDate
First_Name = "Jiang"
Last_Name = "Sam"
Address = ""
HireDate = {^2017-06-05}
cprogramname=[] &&用来判断修改者
PROCEDURE GetHireDate
RETURN This.HireDate
ENDPROC
PROCEDURE hiredate_assign
PARAMETERS m.vnewval
m.voldval=this.hiredate
if strextract(this.cprogramname,[.],[])==UPPER([sethiredate])
*!* 检查cprogramname修改者是不是我们制定的方法
this.hiredate=m.vnewval
ELSE
this.hiredate=m.voldval
ENDIF
this.cprogramname=[] &&恢复不可修改状态
PROCEDURE sethiredate
this.cprogramname=PROGRAM() &&传递方法名给属性cprogramname
this.hiredate=DATE()
ENDDEFINE