Question

我希望你能给我建议。我试图首次使用ADA 95的面向对象功能，并且我希望两个派生类cyclicgroup和polyggroup调用属于其基类的put（）方法， abstractGroup。但是编译器并没有像我期望的那样跟踪类层次结构，只是告诉我在对put（）的调用中类型不匹配。如何告诉编译器识别对象之间的连接？

这里有5个文件，其中所有多余的东西都已删除，并尝试编译：

grpdriver2.adb：

与Ada.Text_IO;使用Ada.Text_IO; 与Ada.Command_Line;使用Ada.Command_Line;

with groupstuff2; 与subgrphandler2;

procedure grpdriver2 is
    cycg:  groupStuff2.cyclicgroup;
    polyg: groupStuff2.polygonGroup;
begin

    cycg := groupstuff2.createCyclicGroup( 10);
    subgrphandler2.put(cycg);   -- line 13

    ------------------------------------------------------------------------------------------------------------------

    polyg := groupstuff2.createPolygonGroup( 10);
    subgrphandler2.put(polyg);     -- line 18

end grpdriver2;

............................................... ................................................... ................

groupstuff2.ads：

与Ada.Text_IO;使用Ada.Text_IO; 与Ada.Command_Line;使用Ada.Command_Line;

groupstuff2软件包为

type abstractGroup is tagged record
    x: integer;
end record;


type cyclicGroup is new abstractGroup with record
    y: integer;
end record;


function createCyclicGroup( size: in integer)  return cyclicGroup ;

----------------------------------------

type polygonGroup is new abstractGroup with record
    null;
end record;

function createPolygonGroup( size: in integer) return polygonGroup ;

end groupstuff2;

............................................... ........................................

groupstuff2.adb：

包主体groupstuff2为

procedure put( g: in abstractGroup) is
    x: integer;
begin
    x := 1;
end put;


function createCyclicGroup( size: in integer)  return cyclicGroup is
    cycg: cyclicGroup;
begin
    cycg.x := size;

    return cycg;

end createCyclicGroup;

function createPolygonGroup( size: in integer) return polygonGroup is
    polyg: polygonGroup;
begin
    polyg.x := size;


    return polyg;

end createPolygonGroup;

end groupstuff2;

............................................... ...............................

subgrphandler2.ads：

与Ada.Text_IO;使用Ada.Text_IO; 与Ada.Command_Line;使用Ada.Command_Line;

with groupstuff2;

包subgrphandler2是

procedure  put( g: in groupStuff2.abstractGroup);

end subgrphandler2;

............................................... ............................................

subgrphandler2.adb：

包主体subgrphandler2为

procedure  put( g: in groupStuff2.AbstractGroup) is

begin
        put("THIS IS A PUT STATMENT");      
end put;

end subgrphandler2;

比较尝试：

C：\ GNAT \ 2018 \ bin \ ceblang> gnatmake grpdriver2 gcc -c grpdriver2.adb grpdriver2.adb：13：36：在groupstuff2.ads:7处定义的预期类型“ abstractGroup” grpdriver2.adb：13：36：找到在groupstuff2.ads:16处定义的类型“ cyclicGroup” grpdriver2.adb：18：36：在groupstuff2.ads:7处定义的预期类型“ abstractGroup” grpdriver2.adb：18：36：找到在groupstuff2.ads:25处定义的类型“ polygonGroup” gnatmake：“ grpdriver2.adb”编译错误

Answer 1

我无法使用GNAT CE 2018（仅支持Ada 2012）来编译Ada95代码，但是似乎您需要将Class属性添加到{{1}的参数类型中} put中的}使其接受类宽类型（即subgrphandler2及其所有扩展名（继承的类型））。

您可能还想通过在其定义中添加groupStuff2.AbstractGroup关键字来使groupStuff2.AbstractGroup实际上是抽象的。

此（重新格式化的代码）在ANAT 2012模式下的GNAT CE 2018上编译：

group_driver_2.adb

abstract

group_stuff_2.ads

with Group_Stuff_2; 
with Sub_Group_Handler_2;

procedure Group_Driver_2 is

   Cycg  : Group_Stuff_2.Cyclic_Group;
   Polyg : Group_Stuff_2.Polygon_Group;

begin

   Cycg := Group_Stuff_2.Create_Cyclic_Group (10);
   Sub_Group_Handler_2.Put (Cycg);

   Polyg := Group_Stuff_2.Create_Polygon_Group (10);
   Sub_Group_Handler_2.Put (Polyg);

end Group_Driver_2;

group_stuff_2.adb

package Group_Stuff_2 is

   type Abstract_Group is abstract tagged 
      record
         X: Integer;
      end record;

   --  Cyclic_Group 

   type Cyclic_Group is new Abstract_Group with 
      record
         Y: Integer;
      end record;

   function Create_Cyclic_Group
     (Size: in Integer)  return Cyclic_Group;

   --  Polygon_Group 

   type Polygon_Group is new Abstract_Group with null record;

   function Create_Polygon_Group
     (Size: in Integer) return Polygon_Group ;

end Group_Stuff_2;

sub_group_handler_2.ads

package body Group_Stuff_2 is

   -------------------------
   -- Create_Cyclic_Group --
   -------------------------

   function Create_Cyclic_Group
     (Size : in Integer) return Cyclic_Group
   is
      Cycg : Cyclic_Group;
   begin
      Cycg.X := Size;
      return Cycg;
   end Create_Cyclic_Group;

   --------------------------
   -- Create_Polygon_Group --
   --------------------------

   function Create_Polygon_Group
     (Size : in Integer) return Polygon_Group 
   is
      Polyg: Polygon_Group;
   begin
      Polyg.X := Size;
      return Polyg;
   end Create_Polygon_Group;

end Group_Stuff_2;

sub_group_handler_2.adb

with Group_Stuff_2;

package Sub_Group_Handler_2 is

   procedure Put (G : in Group_Stuff_2.Abstract_Group'Class);

end Sub_Group_Handler_2;

ADA面向对象的编译错误-我不理解该错误

1 个答案: