REPORT?demo_list_hide?NO?STANDARD?PAGE?HEADING.
*-----------------------------
class?superclass?definition.?定義基類
??public?section.
????data?para(30)?type?c?value?'this?is?super?method!'.
????methods?write_first.
????methods?write.
endclass.

class?subclass?definition?inheriting?from?superclass.?定義派生類
??public?section.
????methods?write_first?redefinition.?定義重載方法
????methods?write_second.
endclass.

class?superclass?implementation.
??method?write_first.
????write:/?para.
????skip.
??endmethod.
??method?write.
????write:/?'super?method?not?inheriting!'.
??endmethod.
endclass.

class?subclass?implementation.
??method?write_first.
????call?method?super->write_first.?通過super調用基類的方法，反之me
??endmethod.
??method?write_second.
????para?=?'the?redifinition?method!'.
????call?method?me->write_first.?通過me調用自身的方法
??endmethod.
endclass.

*------------------------------------------------------

*-基類有多個派生類的時候，所有操作都在派生類中實現，并不需要通過基類定義對象實例，可以將基類定義為一個模板，聲明為抽象類。

*-抽象類包含至少一個抽象方法，不能通過create?object聲明對象實例。抽象方法只包含方法的定義，不包含具體的實現，實現在子類中。

class?superclass2?definition?abstract.??定義一個抽象類
??public?section.
????data?abs(40)?value?'this?is?a?super?abstract!'.
????methods?write_first?abstract.定義抽象方法
endclass.
class?subclass2?definition?inheriting?from?superclass2.
??public?section.
????methods?write_first?redefinition.
????methods?write_second.
endclass.
class?subclass2?implementation.
??method?write_first.
????write:/?'abstract:'.
????write:/?abs.
????skip.
??endmethod.
??method?write_second.
????write:/?'this?is?the?second?method.'.
??endmethod.
endclass.
data?new2?type?ref?to?subclass2.

data?new?type?ref?to?subclass.

start-of-selection.
??create?object?new.
??call?method:?new->write_first,?new->write_second,?new->write.派生類的實例化對象可以調用自身的所有方法，而且可以調用基類的方法，但是方法重載之后，不能通過實例化對象直接調用該方法，需用supper來實現。

create?object?new2.

call?method:?new2->write_first,?new2->write_second.

最終類與最終方法：

最終類和最終方法都是不可以繼承的，為了防止多級別的派生導致的語義語法沖突。

class?finalclass?definition?final.

…………

methods?final_write?final.

endclass.

?

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