Ada编译混乱

Question

我正试着把头转到艾达的头上去。为此，我需要了解如何使用gnatmake命名、编译和链接包文件。

这个网站(http://www.infres.enst.fr/~pautet/Ada95/chap22.htm)有很好的例子，但我不明白如何编译程序的各个部分。

我在看e_c22_p2.ada和e_c22_p3.ada。由此，我创建了一个名为Conveyance1.ads的文件，并将e_c22_p2的内容添加到其中，并在其中添加了一个名为Vehicle1.adb的文件，并在其中添加了e_c22_p3.ada的内容。我使用了gnatmakVehicle1.adb，但是有编译错误。

e_c22_p2.ada包含：

                                            -- Chapter 22 - Program 2
package Conveyance1 is 

   -- This is a very simple transportation type.
   type TRANSPORT is
      record
         Wheels : INTEGER;
         Weight : FLOAT;
      end record;

   procedure Set_Values(Vehicle_In : in out TRANSPORT; 
                        Wheels_In  : INTEGER;
                        Weight_In  : FLOAT);
   function Get_Wheels(Vehicle_In : TRANSPORT) return INTEGER;
   function Get_Weight(Vehicle_In : TRANSPORT) return FLOAT;


   -- This CAR type extends the functionality of the TRANSPORT type.
   type CAR is new TRANSPORT;

   function Tire_Loading(Vehicle_In : CAR) return FLOAT;

end Conveyance1;




package body Conveyance1 is

-- Subprograms for the TRANSPORT record type.
procedure Set_Values(Vehicle_In : in out TRANSPORT; 
                     Wheels_In  : INTEGER; 
                     Weight_In  : FLOAT) is
begin
   Vehicle_In.Wheels := Wheels_In;
   Vehicle_In.Weight := Weight_In;
end Set_Values;

function Get_Wheels(Vehicle_In : TRANSPORT) return INTEGER is
begin
   return Vehicle_In.Wheels;
end Get_Wheels;

function Get_Weight(Vehicle_In : TRANSPORT) return FLOAT is
begin
   return Vehicle_In.Weight;
end Get_Weight;


-- Subprogram for the CAR record type.
function Tire_Loading(Vehicle_In : CAR) return FLOAT is
begin
   return Vehicle_In.Weight / FLOAT(Vehicle_In.Wheels);
end Tire_Loading;

end Conveyance1;




-- Results of execution
--
-- (This package cannot be executed alone.)

Answer 1

文件e_c22_p2.ada包含两个程序单元，即规范和包Conveyance1的主体。

许多Ada编译器会对此很满意，很难说服小虫接受原样，但默认情况下，每个文件需要一个程序单元，文件名等于小写的单位名(用连字符替换)，.ads代表规范，.adb代表主体。

GNAT附带了一个工具gnatchop (请参阅here)，它接受像e_c22_p2.ada这样的输入文件，并将它们分割成预期的源文件(conveyance1.ads和conveyance1.adb)。

Answer 2

正如西蒙所提到的，这个.ada文件有两个部分:规范和正文。因此，创建两个文件如下：

1. Conveyance1.ad-它包含函数、过程、变量的声明
2. Conveyance1.adb -它包含函数的主体、过程 第一个文件

-- Conveyance1.ads
---------------------------------------------------------------------------------
    package Conveyance1 is 

   -- This is a very simple transportation type.
   type TRANSPORT is
      record
         Wheels : INTEGER;
         Weight : FLOAT;
      end record;

   procedure Set_Values(Vehicle_In : in out TRANSPORT; 
                        Wheels_In  : INTEGER;
                        Weight_In  : FLOAT);
   function Get_Wheels(Vehicle_In : TRANSPORT) return INTEGER;
   function Get_Weight(Vehicle_In : TRANSPORT) return FLOAT;


   -- This CAR type extends the functionality of the TRANSPORT type.
   type CAR is new TRANSPORT;

   function Tire_Loading(Vehicle_In : CAR) return FLOAT;

end Conveyance1;

第二份文件，

-- Conveyance1.adb
------------------------------------------------------------------
package body Conveyance1 is

-- Subprograms for the TRANSPORT record type.
procedure Set_Values(Vehicle_In : in out TRANSPORT; 
                     Wheels_In  : INTEGER; 
                     Weight_In  : FLOAT) is
begin
   Vehicle_In.Wheels := Wheels_In;
   Vehicle_In.Weight := Weight_In;
end Set_Values;

function Get_Wheels(Vehicle_In : TRANSPORT) return INTEGER is
begin
   return Vehicle_In.Wheels;
end Get_Wheels;

function Get_Weight(Vehicle_In : TRANSPORT) return FLOAT is
begin
   return Vehicle_In.Weight;
end Get_Weight;


-- Subprogram for the CAR record type.
function Tire_Loading(Vehicle_In : CAR) return FLOAT is
begin
   return Vehicle_In.Weight / FLOAT(Vehicle_In.Wheels);
end Tire_Loading;

end Conveyance1;

这两个是ada包文件。为了使用这些文件，您需要创建另一个.adb (比如demo.adb)文件，如下所示。然后在demo.adb中“使用”和“使用”这些文件

-- demo.adb
------------------------------------------------------------------
with Conveyance1; use Conveyance1;
with Ada.Text_IO; use Ada.Text_IO;


procedure demo is
    my_scooter : TRANSPORT;
begin

    Set_Values(my_scooter, 3, 250.00);    -- it has a sidecar as well !!!!

end demo;

然后，最后用

gnatmake demo.adb

它还将编译您所包含的包。