# Single compilation units

Even before reading [1], we noticed a great speed up in compile time for all PCL libraries if instead of compiling N object files and linking them together, we compile only one, and include all the sources of the N files in this main source. If you peek at an older version of PCL, you might notice things along the lines of:

 1 2 3 4 5 6  // Include the implementations instead of compiling them separately to speed up compile time #include "extract_indices.cpp" #include "passthrough.cpp" #include "project_inliers.cpp" #include "statistical_outlier_removal.cpp" #include "voxel_grid.cpp" 

and in CMakeLists.txt:

 1 2 3 4 5 6 7 8 9  rosbuild_add_library (pcl_ros_filters src/pcl_ros/filters/filter.cpp # Compilation is much faster if we include all the following CPP files in filters.cpp #src/pcl_ros/filters/passthrough.cpp #src/pcl_ros/filters/project_inliers.cpp #src/pcl_ros/filters/extract_indices.cpp #src/pcl_ros/filters/statistical_outlier_removal.cpp #src/pcl_ros/filters/voxel_grid.cpp )