// Current way
int16 FOO=0
int16 BAR=1
int16 value

// Proposed way
enum foo_bar { FOO, BAR }

colcon build --cmake-args -DCMAKE_VERBOSE_MAKEFILE:BOOL=ON --packages-select <package>

ros2 run --prefix 'gdb -ex run --args' package_name executable_name

def generate_launch_description():
    """Generate launch description with multiple components."""
    container = ComposableNodeContainer(
            node_name='my_container',
            node_namespace='',
            package='rclcpp_components',
            node_executable='component_container',
            composable_node_descriptions=[
                ComposableNode(
                    package='composition',
                    node_plugin='composition::Talker',
                    node_name='talker',
                    extra_arguments=[{'use_intra_process_comms': True}]),
                ComposableNode(
                    package='composition',
                    node_plugin='composition::Listener',
                    node_name='listener',
                    extra_arguments=[{'use_intra_process_comms': True}])
            ],
            output='screen',
    )

export RCUTILS_CONSOLE_OUTPUT_FORMAT="[{severity} {time}] [{name}]: {message} ({function_name}() at {file_name}:{line_number})"

ERROR: the following packages/stacks could not have their rosdep keys resolved
to system dependencies:
ros2doctor: No definition of [python3-ifcfg] for OS version [xenial]
rviz_assimp_vendor: No definition of [assimp] for OS version [xenial]
ament_clang_tidy: No definition of [clang-tidy] for OS version [xenial]

Starting >>> tracetools_trace                                                                       
[0.212s] WARNING:colcon.colcon_ros.prefix_path.catkin:The path '/home/bot/Code/rviz/install' in the environment variable CMAKE_PREFIX_PATH seems to be a catkin workspace but it doesn't contain any 'local_setup.*
' files. Maybe the catkin version is not up-to-date?             
[0.212s] WARNING:colcon.colcon_ros.prefix_path.catkin:The path '/home/bot/Development/dr-ros/install_isolated' in the environment variable CMAKE_PREFIX_PATH seems to be a catkin workspace but it doesn't containa
ny 'local_setup.*' files. Maybe the catkin version is not up-to-date?
Traceback (most recent call last):trace - 0.1s]    
  File "<string>", line 1, in <module>                                                        
  File "/usr/lib/python3/dist-packages/colcon_python_setup_py/package_identification/python_setup_py.py", line 111, in get_setup_arguments
    runpy.run_path(str(setup_py))                                                         
  File "/usr/lib/python3.5/runpy.py", line 261, in run_path
    code, fname = _get_code_from_file(run_name, path_name)                                      
  File "/usr/lib/python3.5/runpy.py", line 236, in _get_code_from_file
    code = compile(f.read(), fname, 'exec')                                                                                    
  File "/home/bot/ros2_ws/src/micro-ROS/ros_tracing/ros2_tracing/tracetools_trace/setup.py", line 33
    f'trace = {package_name}.trace:main',                                                                
                                       ^
SyntaxError: invalid syntax                                                                                                                            
--- stderr: tracetools_trace                         
Traceback (most recent call last):                                                                 
  File "/usr/lib/python3/dist-packages/colcon_core/executor/__init__.py", line 91, in __call__
    rc = await self.task(*args, **kwargs)                                                                                                                                                                          
  File "/usr/lib/python3/dist-packages/colcon_core/task/__init__.py", line 92, in __call__                                                                                                                  
    return await task_method(*args, **kwargs)                                                              
  File "/usr/lib/python3/dist-packages/colcon_ros/task/ament_python/build.py", line 50, in build
    setup_py_data = get_setup_data(self.context.pkg, env)                                                                  
  File "/usr/lib/python3/dist-packages/colcon_core/task/python/__init__.py", line 20, in get_setup_data
    return dict(pkg.metadata[key](env))                                                              
  File "/usr/lib/python3/dist-packages/colcon_ros/package_identification/ros.py", line 128, in getter
    str(desc.path / 'setup.py'), env)                                                                                                                                                                              
  File "/usr/lib/python3/dist-packages/colcon_python_setup_py/package_identification/python_setup_py.py", line 209, in get_setup_arguments_with_context                      
    cmd, stdout=subprocess.PIPE, env=env, check=True)                                               
  File "/usr/lib/python3.5/subprocess.py", line 398, in run                                                                                            
    output=stdout, stderr=stderr)
subprocess.CalledProcessError: Command '['/usr/bin/python3', '-c', "import sys;sys.path.insert(0, '/usr/lib/python3');from colcon_python_setup_py.package_identification.python_setup_py import get_setup_arguments
;output = repr(get_setup_arguments('/home/bot/ros2_ws/src/micro-ROS/ros_tracing/ros2_tracing/tracetools_trace/setup.py'));sys.stdout.buffer.write(output.encode('utf-8'))"]' returned non-zero exit status 1
---
Failed   <<< tracetools_trace   [ Exited with code 1 ]

Summary: 0 packages finished [0.30s]
  1 package failed: tracetools_trace
  1 package had stderr output: tracetools_trace
Command '['/usr/bin/python3', '-c', "import sys;sys.path.insert(0, '/usr/lib/python3');from colcon_python_setup_py.package_identification.python_setup_py import get_setup_arguments;output = repr(get_setup_argume
nts('/home/bot/ros2_ws/src/micro-ROS/ros_tracing/ros2_tracing/tracetools_trace/setup.py'));sys.stdout.buffer.write(output.encode('utf-8'))"]' returned non-zero exit status 1

cd ~
python3.6 -m venv virtualenv --without-pip
cd virtualenv/
source bin/activate

raceback (most recent call last):
  File "/usr/bin/vcs", line 6, in <module>
    from pkg_resources import load_entry_point
  File "/usr/local/lib/python3.6/site-packages/pkg_resources/__init__.py", line 3017, in <module>
    @_call_aside
  File "/usr/local/lib/python3.6/site-packages/pkg_resources/__init__.py", line 3003, in _call_aside
    f(*args, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/pkg_resources/__init__.py", line 3030, in _initialize_master_working_set
    working_set = WorkingSet._build_master()
  File "/usr/local/lib/python3.6/site-packages/pkg_resources/__init__.py", line 659, in _build_master
    ws.require(__requires__)
  File "/usr/local/lib/python3.6/site-packages/pkg_resources/__init__.py", line 967, in require
    needed = self.resolve(parse_requirements(requirements))
  File "/usr/local/lib/python3.6/site-packages/pkg_resources/__init__.py", line 853, in resolve
    raise DistributionNotFound(req, requirers)
pkg_resources.DistributionNotFound: The 'vcstool==0.2.4' distribution was not found and is required by the application

$ head /usr/bin/vcs
#!/usr/bin/python3.5

colcon build --symlink-install           Traceback (most recent call last):
  File "/usr/bin/colcon", line 6, in <module>                                                                                                                                       
    from pkg_resources import load_entry_point 
  File "/usr/local/lib/python3.6/site-packages/pkg_resources/__init__.py", line 3017, in <module>                                                                          
    @_call_aside                                   
  File "/usr/local/lib/python3.6/site-packages/pkg_resources/__init__.py", line 3003, in _call_aside                                                                     
    f(*args, **kwargs)                                 
  File "/usr/local/lib/python3.6/site-packages/pkg_resources/__init__.py", line 3030, in _initialize_master_working_set                                                        
    working_set = WorkingSet._build_master()   
  File "/usr/local/lib/python3.6/site-packages/pkg_resources/__init__.py", line 659, in _build_master                                                                       
    ws.require(__requires__)                            
  File "/usr/local/lib/python3.6/site-packages/pkg_resources/__init__.py", line 967, in require
    needed = self.resolve(parse_requirements(requirements))
  File "/usr/local/lib/python3.6/site-packages/pkg_resources/__init__.py", line 853, in resolve
    raise DistributionNotFound(req, requirers)
pkg_resources.DistributionNotFound: The 'colcon-core==0.4.3' distribution was not found and is required by the application

--- stderr: rviz_rendering
CMake Warning at /home/bot/ros2_dashing/install/ament_cmake_gmock/share/ament_cmake_gmock/cmake/ament_add_gmock.cmake:67 (add_executable):
  Cannot generate a safe runtime search path for target
  billboard_line_test_target because files in some directories may conflict
  with libraries in implicit directories:

    runtime library [libfreetype.so.6] in /usr/lib/x86_64-linux-gnu may be hidden by files in:
      /home/bot/anaconda2/lib
    runtime library [libz.so.1] in /usr/lib/x86_64-linux-gnu may be hidden by files in:
      /home/bot/anaconda2/lib
    runtime library [libcurl.so.4] in /usr/lib/x86_64-linux-gnu may be hidden by files in:
      /home/bot/anaconda2/lib

  Some of these libraries may not be found correctly.
Call Stack (most recent call first):
  /home/bot/ros2_dashing/install/ament_cmake_gmock/share/ament_cmake_gmock/cmake/ament_add_gmock.cmake:50 (_ament_add_gmock)
  CMakeLists.txt:203 (ament_add_gmock)


CMake Warning at /home/bot/ros2_dashing/install/ament_cmake_gmock/share/ament_cmake_gmock/cmake/ament_add_gmock.cmake:67 (add_executable):
  Cannot generate a safe runtime search path for target
  movable_text_test_target because files in some directories may conflict
  with libraries in implicit directories:

    runtime library [libfreetype.so.6] in /usr/lib/x86_64-linux-gnu may be hidden by files in:
      /home/bot/anaconda2/lib
    runtime library [libz.so.1] in /usr/lib/x86_64-linux-gnu may be hidden by files in:
      /home/bot/anaconda2/lib
    runtime library [libcurl.so.4] in /usr/lib/x86_64-linux-gnu may be hidden by files in:
      /home/bot/anaconda2/lib

...


/usr/lib/x86_64-linux-gnu/libSM.so: undefined reference to `uuid_generate@UUID_1.0'
/home/bot/anaconda2/lib/libpng16.so.16: undefined reference to `inflateValidate@ZLIB_1.2.9'
/usr/lib/x86_64-linux-gnu/libSM.so: undefined reference to `uuid_unparse_lower@UUID_1.0'
collect2: error: ld returned 1 exit status

conda remove libpng
sudo apt-get install libpng16-16

--- stderr: ros1_bridge                                                     
Traceback (most recent call last):                                                                                            
  File "bin/ros1_bridge_generate_factories", line 11, in <module>                    
    from ros1_bridge import generate_cpp                                               
  File "/home/bot/ros2_dashing/src/ros2/ros1_bridge/ros1_bridge/__init__.py", line 23, in <module>
    import genmsg                                                           
ImportError: No module named 'genmsg'                              
make[2]: *** [generated/get_factory.cpp] Error 1                                     
make[1]: *** [CMakeFiles/ros1_bridge.dir/all] Error 2
make: *** [all] Error 2

[0.844s] WARNING:colcon.colcon_core.package_selection:ignoring unknown package 'ros1_bridge' in --packages-select
                     
Summary: 0 packages finished [1.18s]
[1.527s] WARNING:colcon.colcon_ros.prefix_path.catkin:The path '/home/bot/Development/dr-ros/install_isolated' in the environment variable CMAKE_PREFIX_PATH seems to be a catkin workspace but it doesn't contain any 'local_setup.*' files. Maybe the catkin version is not up-to-date?

Could not import "pyqt" bindings of qt_gui_cpp library - so C++ plugins will not be available:
Traceback (most recent call last):                                                                           
  File "/home/bot/ros2_dashing/install/qt_gui_cpp/lib/python3.5/site-packages/qt_gui_cpp/cpp_binding_helper.py", line 43, in <module>
    from . import libqt_gui_cpp_sip                                                        
ImportError: /usr/lib/x86_64-linux-gnu/libQt5Core.so.5: version `Qt_5.9' not found (required by /home/bot/ros2_dashing/install/qt_gui_cpp/lib/python3.5/site-packages/qt_gui_cpp/libqt_gui_cpp_sip.so)
                                                                                       
RosPluginProvider.load(rqt_gui_py/RosPyPluginProvider) exception raised in __builtin__.__import__(rqt_gui_py.ros_py_plugin_provider, [RosPyPluginProvider]):
Traceback (most recent call last):                                                         
  File "/home/bot/ros2_dashing/build/rqt_gui/src/rqt_gui/ros_plugin_provider.py", line 81, in load
    attributes['module_name'], fromlist=[attributes['class_from_class_type']], level=0)      
ImportError: No module named 'rqt_gui_py'                                                  
                                                                                               
RecursivePluginProvider.discover() loading plugin "rqt_gui_py/RosPyPluginProvider" failed:
Traceback (most recent call last):                                                     
  File "/home/bot/ros2_dashing/install/qt_gui/lib/python3.5/site-packages/qt_gui/recursive_plugin_provider.py", line 60, in discover
    instance = self._plugin_provider.load(plugin_descriptor.plugin_id(), None)
  File "/home/bot/ros2_dashing/build/rqt_gui/src/rqt_gui/ros_plugin_provider.py", line 91, in load
    raise e
  File "/home/bot/ros2_dashing/build/rqt_gui/src/rqt_gui/ros_plugin_provider.py", line 81, in load
    attributes['module_name'], fromlist=[attributes['class_from_class_type']], level=0)
ImportError: No module named 'rqt_gui_py'

Traceback (most recent call last):
  File "/home/bot/ros2_dashing/install/rqt_console/lib/rqt_console/rqt_console", line 5, in <module>
    from rqt_gui.main import Main
ImportError: No module named 'rqt_gui'

terminate called after throwing an instance of 'rclcpp::exceptions::ParameterAlreadyDeclaredException'
what():  parameter '' has already been declared      
Aborted (core dumped)

ros2 lifecycle set <nodename> shutdown

kill -9 $(pgrep -f "`which ros2` launch")

terminate called after throwing an instance of 'rclcpp_action::exceptions::UnknownGoalHandleError'                                            
[singulation_app-5]   what():  Goal handle is not known to this client.