Add pkg-config files for control libraries

[domire8]

Similar to a recent PR on network-interfaces, I'm adding here the pkg-config files to the control libraries. For each module, I'm creating a separate file and then I'm also creating one for the top level cmake project that summarizes the 4 modules. The result are 5 files:

• /usr/local/lib/pkgconfig/state_representation.pc:

  prefix=/usr/local
  exec_prefix=${prefix}
  includedir=${prefix}/include
  libdir=${exec_prefix}/lib
  
  Name: state_representation
  Description: This library provides a set of classes to represent states in Cartesian and joint space.
  Version: 6.3.1
  Requires: eigen3 >= 3.4.0
  Cflags: -I${includedir} 
  Libs: -L${libdir}
  

• /usr/local/lib/pkgconfig/dynamical_systems.pc:

  prefix=/usr/local
  exec_prefix=${prefix}
  includedir=${prefix}/include
  libdir=${exec_prefix}/lib
  
  Name: dynamical_systems
  Description: This library provides a set of classes to represent dynamical systems; functions which map a state to a state derivative.
  Version: 6.3.1
  Requires: state_representation >= 6.3.1
  Cflags: -I${includedir} 
  Libs: -L${libdir}
  

• /usr/local/lib/pkgconfig/robot_model.pc:

  prefix=/usr/local
  exec_prefix=${prefix}
  includedir=${prefix}/include
  libdir=${exec_prefix}/lib
  
  Name: robot_model
  Description: This library is a wrapper for the pinocchio library, used to compute dynamics model of a robot.
  Version: 6.3.1
  Requires: state_representation >= 6.3.1, pinocchio >= 2.6.9
  Cflags: -I${includedir} -lOsqpEigen
  Libs: -L${libdir}
  

• /usr/local/lib/pkgconfig/controllers.pc:

  prefix=/usr/local
  exec_prefix=${prefix}
  includedir=${prefix}/include
  libdir=${exec_prefix}/lib
  
  Name: controllers
  Description: This library introduces a set of controllers to be used in robotic control-loop schemes.
  Version: 6.3.1
  Requires: robot_model >= 6.3.1
  Cflags: -I${includedir} 
  Libs: -L${libdir}
  

• /usr/local/lib/pkgconfig/control_libraries.pc:

  prefix=/usr/local
  exec_prefix=${prefix}
  includedir=${prefix}/include
  libdir=${exec_prefix}/lib
  
  Name: control_libraries
  Description: control_libraries
  Version: 6.3.1
  Requires: state_representation >= 6.3.1, dynamical_systems >= 6.3.1, controllers >= 6.3.1, robot_model >= 6.3.1
  Cflags: -I${includedir} 
  Libs: -L${libdir}
  

Of course, the Requires tags in that last file will only be filled with the libraries that are actually installed.

It's a small feature that will most likely not used a lot but it can't hurt to do it. My main motivation is to add it here such that other packages can create pkg-config files where we add Requires: control_libraries. This wouldn't be possible if control libraries doesn't have pkg-config files itself.

[eeberhard]

Seems like a great addition. Thanks for advancing our project configuration with more cmake magic!

[eeberhard]

The base config input file was renamed, but the generated output is still ${PROJECT_NAME}Config.cmake. Should it also be changed to the lowercase naming convention <lowercasePackageName>-config.cmake? It shouldn't be a breaking change since find_package looks for both name types but I would also make sure that's tested before confirming it.

[domire8]

Hm yeah good point, I think I like ${PROJECT_NAME}Config.cmake better. I renamed the file

[eeberhard]

Indentation looks a bit off here

Suggested change

	if(PKGCONFIG_LIBRARIES)
	set(PKGCONFIG_LIBRARIES "${PKGCONFIG_LIBRARIES}, ${ARGV0} >= ${ARGV1}")
	else()
	set(PKGCONFIG_LIBRARIES "${ARGV0} >= ${ARGV1}")
	endif()
	if(PKGCONFIG_LIBRARIES)
	set(PKGCONFIG_LIBRARIES "${PKGCONFIG_LIBRARIES}, ${ARGV0} >= ${ARGV1}")
	else()
	set(PKGCONFIG_LIBRARIES "${ARGV0} >= ${ARGV1}")
	endif()

[eeberhard]

The semicolon here is not quite right - I would suggest a hyphen or colon instead.

Suggested change

	set(PKG_DESC "This library provides a set of classes to represent dynamical systems; functions which map a state to a state derivative.")
	set(PKG_DESC "This library provides a set of classes to represent dynamical systems: functions which map a state to a state derivative.")