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编写一个基于SimpleActionClient的回调函数
Description: 相比一个简单的线性脚本，使用回调函数的示例程序流会更复杂。Tutorial Level: ADVANCED
示例
在一些情况下，阻塞直到一个目标完成不会提供足够的灵活。相反的，基于事件运行或许需要更多场景。在以下例程中，提供如何使用回调来避免调用waitForResult()来阻塞用于目标完成。
1 #include <ros/ros.h>
2 #include <actionlib/client/simple_action_client.h>
3 #include <actionlib_tutorials/FibonacciAction.h>
4
5 using namespace actionlib_tutorials;
6 typedef actionlib::SimpleActionClient<FibonacciAction> Client;
7
8 // Called once when the goal completes
9 void doneCb(const actionlib::SimpleClientGoalState& state,
10 const FibonacciResultConstPtr& result)
11 {
12 ROS_INFO("Finished in state [%s]", state.toString().c_str());
13 ROS_INFO("Answer: %i", result->sequence.back());
14 ros::shutdown();
15 }
16
17 // Called once when the goal becomes active
18 void activeCb()
19 {
20 ROS_INFO("Goal just went active");
21 }
22
23 // Called every time feedback is received for the goal
24 void feedbackCb(const FibonacciFeedbackConstPtr& feedback)
25 {
26 ROS_INFO("Got Feedback of length %lu", feedback->sequence.size());
27 }
28
29 int main (int argc, char **argv)
30 {
31 ros::init(argc, argv, "test_fibonacci_callback");
32
33 // Create the action client
34 Client ac("fibonacci", true);
35
36 ROS_INFO("Waiting for action server to start.");
37 ac.waitForServer();
38 ROS_INFO("Action server started, sending goal.");
39
40 // Send Goal
41 FibonacciGoal goal;
42 goal.order = 20;
43 ac.sendGoal(goal, &doneCb, &activeCb, &feedbackCb);
44
45 ros::spin();
46 return 0;
47 }
但我想要使用类!
当尝试注册类方法时，注册目标、活跃和反馈回调的语法并不是很方便。然而，这已经完成了，通过"超级有用但有时很难得到正确的语法" boost::bind (查看boost 文档).
以下是一个其他Fibonnaci ActionClient的示例，使用到类：
1 #include <ros/ros.h>
2 #include <actionlib/client/simple_action_client.h>
3 #include <actionlib_tutorials/FibonacciAction.h>
4
5 using namespace actionlib_tutorials;
6 typedef actionlib::SimpleActionClient<FibonacciAction> Client;
7
8 class MyNode
9 {
10 public:
11 MyNode() : ac("fibonacci", true)
12 {
13 ROS_INFO("Waiting for action server to start.");
14 ac.waitForServer();
15 ROS_INFO("Action server started, sending goal.");
16 }
17
18 void doStuff(int order)
19 {
20 FibonacciGoal goal;
21 goal.order = order;
22
23 // Need boost::bind to pass in the 'this' pointer
24 ac.sendGoal(goal,
25 boost::bind(&MyNode::doneCb, this, _1, _2),
26 Client::SimpleActiveCallback(),
27 Client::SimpleFeedbackCallback());
28
29 }
30
31 void doneCb(const actionlib::SimpleClientGoalState& state,
32 const FibonacciResultConstPtr& result)
33 {
34 ROS_INFO("Finished in state [%s]", state.toString().c_str());
35 ROS_INFO("Answer: %i", result->sequence.back());
36 ros::shutdown();
37 }
38
39 private:
40 Client ac;
41 };
42
43 int main (int argc, char **argv)
44 {
45 ros::init(argc, argv, "test_fibonacci_class_client");
46 MyNode my_node;
47 my_node.doStuff(10);
48 ros::spin();
49 return 0;
50 }
这个示例的关键所在是调用sendGoal ，该函数使用boost::bind： https://raw.githubusercontent.com/ros/common_tutorials/hydro-devel/actionlib_tutorials/src/fibonacci_class_client.cpp
1 #include <ros/ros.h>
2 #include <actionlib/client/simple_action_client.h>
3 #include <actionlib_tutorials/FibonacciAction.h>
4
5 using namespace actionlib_tutorials;
6 typedef actionlib::SimpleActionClient<FibonacciAction> Client;
7
8 class MyNode
9 {
10 public:
11 MyNode() : ac("fibonacci", true)
12 {
13 ROS_INFO("Waiting for action server to start.");
14 ac.waitForServer();
15 ROS_INFO("Action server started, sending goal.");
16 }
17
18 void doStuff(int order)
19 {
20 FibonacciGoal goal;
21 goal.order = order;
22
23 // Need boost::bind to pass in the 'this' pointer
24 ac.sendGoal(goal,
25 boost::bind(&MyNode::doneCb, this, _1, _2),
26 Client::SimpleActiveCallback(),
27 Client::SimpleFeedbackCallback());
28
29 }
30
31 void doneCb(const actionlib::SimpleClientGoalState& state,
32 const FibonacciResultConstPtr& result)
33 {
34 ROS_INFO("Finished in state [%s]", state.toString().c_str());
35 ROS_INFO("Answer: %i", result->sequence.back());
36 ros::shutdown();
37 }
38
39 private:
40 Client ac;
41 };
42
43 int main (int argc, char **argv)
44 {
45 ros::init(argc, argv, "test_fibonacci_class_client");
46 MyNode my_node;
47 my_node.doStuff(10);
48 ros::spin();
49 return 0;
50 }
我们不注册活跃或反馈回调函数，因此我们可以使用传递null函数指针来代替。我们也可以通过设置两个参数为空来使用，因为默认的回调函数为null。
