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I'd appreciate it if someone can explain the reason why the actionlib simpleServer constructor needs to be initialized as a constructor initializer list? If the initialization's removed the compilation fails.
reference to actionlib tutorials
I know this is more as a C++ question rather than ROS related question!
Thank you.
You are correct; this is a C++ question.
The actionlib::SimpleActionServerclass does not have a default constructor: http://docs.ros.org/melodic/api/actio...
Therefore, you must provide constructor arguments when the SimpleActionServer object is constructed. If this object is a member of another class, then the C++ standard states that the constructor arguments must be passed in the initializer list.
Before the compound statement that forms the function body of the constructor begins executing, initialization of all direct bases, virtual bases, and non-static data members is finished. Member initializer list is the place where non-default initialization of these objects can be specified.
I tend to use cppreference.com for C++ reference material, but you will probably find that a textbook aimed at teaching C++ explains the material in a more approachable way.
Asked: 2019-10-19 20:16:07 -0600
Seen: 512 times
Last updated: Oct 19 '19
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Aside of ahendrix correct answer below, a suggestion:
If you want to initiate the action server at another moment, you can consider wrapping the
actionlib::SimpleActionServerin astd::shared_ptr. I would not suggest it as the default approach, but it can be useful in cases where the action server is not supposed to be active directly at the time of calling the constructor of your class.If with
you mean it may be desirable to not have the
ActionServerinstantiated then delaying construction by using a (smart) pointer is indeed an option.If you were instead thinking of "initiate" as: placing the server in the active state, then perhaps setting
auto_starttofalse(ctor docs) would be a better approach.Good point, I was not thinking of the
auto_startoption, which is indeed a better approach.