QtTaskTree::Group Class

class QtTaskTree::Group

“组”是构成声明式配方的基础单元，用于描述如何执行和处理一个嵌套的异步任务树。更多内容...

标题：	`#include <qtasktree.h>`

CMake：	`find_package(Qt6 REQUIRED COMPONENTS TaskTree)` `target_link_libraries(mytarget PRIVATE Qt6::TaskTree)`
qmake：	`QT += tasktree`
自：	Qt 6.11
继承自：	QtTaskTree::ExecutableItem
状态：	技术预览

该类处于技术预览阶段，内容可能会有变动。

所有成员的列表（包括继承的成员）

注意：该类中的所有函数均为可重入函数。

公共函数

	Group(const QtTaskTree::GroupItems &children)
	Group(std::initializer_list<QtTaskTree::GroupItem> children)

详细说明

Group 是其他组项的容器。它将子任务封装成一个单元，该单元在组的父级看来是一个单一的异步任务。由于 Group 属于GroupItem 类型，因此它也可以是 Group 的子项。

使用别名自定义任务名称将子任务插入组中，例如：QThreadFunctionTask<ResultType> 或QNetworkReplyWrapperTask ：

const Group group {
    QNetworkReplyWrapperTask(...),
    QThreadFunctionTask<int>(...)
};

您可以通过插入ExecutionMode 或WorkflowPolicy 项来自定义该组的行为：

const Group group {
    parallel,
    continueOnError,
    QNetworkReplyWrapperTask(...),
    QNetworkReplyWrapperTask(...)
};

该组可以包含嵌套组：

const Group group {
    finishAllAndSuccess,
    QNetworkReplyWrapperTask(...),
    Group {
        QNetworkReplyWrapperTask(...),
        Group {
            parallel,
            QNetworkReplyWrapperTask(...),
            QNetworkReplyWrapperTask(...),
        }
        QThreadFunctionTask<QString>(...)
    }
};

该组可动态实例化自定义存储结构，该结构可用于任务间的数据交换：

struct MyCustomStruct { QByteArray data; };

Storage<MyCustomStruct> storage;

const auto onFirstSetup = [](QNetworkReplyWrapper &task) { ... };
const auto onFirstDone = [storage](const QNetworkReplyWrapper &task) {
    // storage-> gives a pointer to MyCustomStruct instance,
    // created dynamically by the running task tree.
    storage->data = task.reply()->readAll();
};
const auto onSecondSetup = [storage](QThreadFunction<QImage> &task) {
    // storage-> gives a pointer to MyCustomStruct. Since the group is sequential,
    // the stored MyCustomStruct was already updated inside the onFirstDone handler.
    const QByteArray storedData = storage->data;
};

const Group group {
    // When the group is entered by a running task tree, it creates MyCustomStruct
    // instance dynamically. It is later accessible from all handlers via
    // the *storage or storage-> operators.
    sequential,
    storage,
    QNetworkReplyWrapperTask(onFirstSetup, onFirstDone, CallDoneFlag::OnSuccess),
    QThreadFunctionTask<QImage>(onSecondSetup)
};

成员函数文档

Group::Group(const QtTaskTree::GroupItems &children)

根据给定的children 列表构建一个组。

当组的子项在编译时未知，而需在后续的运行时确定时，此构造函数非常有用：

const QStringList sourceList = ...;

GroupItems groupItems { parallel };

for (const QString &source : sourceList) {
    const QNetworkReplyWrapperTask task(...); // use source for setup handler
    groupItems << task;
}

const Group group(groupItems);

Group::Group(std::initializer_list<QtTaskTree::GroupItem> children)

根据children 生成的std::initializer_list 构建一个组。

当组的所有子项在编译时已知时，此构造函数非常有用：

const Group group {
    finishAllAndSuccess,
    QNetworkReplyWrapperTask(...),
    Group {
        QNetworkReplyWrapperTask(...),
        Group {
            parallel,
            QNetworkReplyWrapperTask(...),
            QNetworkReplyWrapperTask(...),
        }
        QThreadFunctionTask<QString>(...)
    }
};

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