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"Cannot allocate an object of abstract type [...]" due to PLUGINLIB_EXPORT_CLASS

asked 2016-06-28 01:54:17 -0600

Megacephalo gravatar image

Hi all,

I have been trying to create a Rviz plugin to plant multiple waypoints on the map, I refer to PlantFlagTool and try to make one out of my own. The problem when I did so from scratch is that the compiler complains the following error:

In instantiation of ‘B* class_loader::class_loader_private::MetaObject<C, B>::create() const [with C = rviz_waypoint_assigner::RvizWaypointAssigner; B = rviz::Tool]’:

(...)

cannot allocate an object of abstract type ‘rviz_waypoint_assigner::RvizWaypointAssigner’
      return new C;
                 ^

But I did whatever I could to get the plug-in to get to the ROS tool-chain. Is it because I missed the exact procedure to make the plug-in functional? Thank you in advance !

Here is the barebone of my codes:

CMakeLists.txt

cmake_minimum_required(VERSION 2.8.3)
project(iceira_waypoint_provider)

find_package(catkin REQUIRED COMPONENTS
  roscpp
  rospy
  rviz
  visualization_msgs
)

find_package(PkgConfig)

include_directories( include
  ${catkin_INCLUDE_DIRS}
)

link_directories(${catkin_LIBRARY_DIRS})

catkin_package(
    INCLUDE_DIRS include
    LIBRARIES ${PROJECT_NAME}
    CATKIN_DEPENDS roscpp visualization_msgs
)

add_library(${PROJECT_NAME} src/rviz_waypoints_assigner.cpp)

target_link_libraries(${PROJECT_NAME} ${catkin_LIBRARIES})

package.xml

<?xml version="1.0"?>
<package>
  <name>iceira_waypoint_provider</name>
  <version>0.0.0</version>

  <buildtool_depend>catkin</buildtool_depend>
  <build_depend>roscpp</build_depend>
  <build_depend>rospy</build_depend>
  <build_depend>rviz</build_depend>
  <build_depend>visualization_msgs</build_depend>
  <build_depend>geometry_msgs</build_depend>

  <run_depend>roscpp</run_depend>
  <run_depend>rospy</run_depend>
  <run_depend>rviz</run_depend>
  <run_depend>visualization_msgs</run_depend>
  <run_depend>geometry_msgs</run_depend>

  <export>
      <rviz plugin="${prefix}/plugin_description.xml"/>
  </export>
</package>

plugin_description.xml

<library path="lib/libiceira_waypoint_provider">
  <class name="rviz_waypoint_assigner/RvizWaypointAssigner"
     type="rviz_waypoint_assigner::RvizWaypointAssigner"
     base_class_type="rviz::Tool">
  </class>
</library>

rviz_waypoints_assigner.h

#ifndef _RVIZ_WAYPOINT_ASSIGNER_
#define _RVIZ_WAYPOINT_ASSIGNER_

#include <rviz/tool.h>
#include <boost/concept_check.hpp>

namespace rviz_waypoint_assigner {
  class RvizWaypointAssigner : public rviz::Tool
  {
  public:
    RvizWaypointAssigner();
    ~RvizWaypointAssigner();

    virtual void onInitialize() ;

    virtual void activate() ;
    virtual void deactive() ;



  private:

  } ; // class RvizWaypointAssigner
} // namespace rviz_plugin_tutorials
#endif

rviz_viewpoints_assigner.cpp

#include <ros/console.h>

#include "iceira_waypoint_provider/rviz_waypoints_assigner.h"

namespace rviz_waypoint_assigner {

RvizWaypointAssigner::RvizWaypointAssigner()
{
  // do something
}

RvizWaypointAssigner::~RvizWaypointAssigner()
{
    // do something
}

void RvizWaypointAssigner::onInitialize()
{
  // do something
}

void RvizWaypointAssigner::activate()
{
    // do something
}

void RvizWaypointAssigner::deactive()
{
    // do something
}


} // namespace rviz_waypoint_assigner

#include <pluginlib/class_list_macros.h>
PLUGINLIB_EXPORT_CLASS(rviz_waypoint_assigner::RvizWaypointAssigner, rviz::Tool )
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1 Answer

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answered 2016-06-28 02:20:24 -0600

gvdhoorn gravatar image

updated 2016-06-28 02:21:17 -0600

The problem is that the compiler expects you to have implemented all methods declared in rviz::Tool. If you don't, you've essentially created something called an abstract base class.

  class RvizWaypointAssigner : public rviz::Tool
  {
  public:
    ...
    virtual void activate() ;
    virtual void deactive() ;
    ...
  };

Looking at the rviz::Tool API docs, the last method is actually called deactivate(), not deactive() (see the docs as well).

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Comments

thank you @gvdhoorn. By correcting that simple typo, everything works! So, I really need to learn more how to use API for verification ! Thanks!

Megacephalo gravatar imageMegacephalo ( 2016-06-28 05:12:06 -0600 )edit

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Asked: 2016-06-28 01:54:17 -0600

Seen: 89 times

Last updated: Jun 28 '16