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concurrency - 预期的私有类型“Ada.Real_Time.Time_Span”

问题描述

我有以下任务主体：

with Ada.Text_IO; use Ada.Text_IO;
with Ada.Real_Time; use Ada.Real_Time;
with Ada.Task_Identification; use Ada.Task_Identification;

package body pkg_task is
    task body task_t is
        activationTime : Time_Span := 1; -- 1 second
        period : Time_Span := 2; -- 2000 milliseconds
        computingTime : Time_Span := 1; -- 1000 milliseconds
        activeWaiting : Integer;
        startingTime : Time;
    begin
        delay To_Duration(activationTime);

        startingTime := Clock;

        while (Clock - startingTime) < computingTime loop
            activeWaiting := activeWaiting + 1;

            Put_Line("Task(" & Image(Current_Task) & "): Internal variable: " & Integer'Image(activeWaiting));

            if (period - (Clock - startingTime)) < computingTime then
                delay To_Duration(period - (Clock - startingTime));
            end if;
        end loop;
    end task_t;
end pkg_task;

编译时，我得到了提到的错误：

gcc-7 -c pkg_task.adb
pkg_task.adb:8:47: expected private type "Ada.Real_Time.Time_Span"
pkg_task.adb:8:47: found type universal integer
pkg_task.adb:9:39: expected private type "Ada.Real_Time.Time_Span"
pkg_task.adb:9:39: found type universal integer
pkg_task.adb:10:46: expected private type "Ada.Real_Time.Time_Span"
pkg_task.adb:10:46: found type universal integer

问题是我对这门语言很陌生，而且我不太了解它。事实上，我可以说它有点复杂，而且我在 Internet 上找不到太多信息。

标签： concurrencytaskada

解决方案

由于 Time_Span 是私有类型，因此不会自动转换文字。尝试：

To_Time_Span (1.0)

此外，由于 To_Time_Span 的参数是实数类型（持续时间），因此您需要小数部分。Ada 不会让您在没有显式转换的情况下混合整数和实数类型。

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