Manually Including External Libraries

Occasionally, a C++ component may require building and linking with a library that is not packaged as a REDHAWK shared library. This section details how to manually configure the compiler and linker flags. Two examples are given:

• using a pkg-config (.pc) file to find and link against a library - enables your project to check for the presence of the library and issue an error while running configure if the library is not found, and enables you to avoid hard-coded options.
• directly linking against a library - enables you to directly supply the compiler/linker flags and can be used if a pkg-config file is not available.

Adding a Library by Referencing a pkg-config File

To add a library by referencing a pkg-config (.pc) file, edit the configure.ac file in your component's implementation directory.

1. Open the configure.ac file in your component's implementation directory.

2. Locate the following line referencing PROJECTDEPS in the code:

PKG_CHECK_MODULES([PROJECTDEPS], [ossie >= 2.0 omniORB4 >= 4.1.0])

1. Add your library to the list of requirements. For example, if you need version 1.2.3 or greater of the foo library:

PKG_CHECK_MODULES([PROJECTDEPS], [
  ossie >= 2.0
  omniORB4 >= 4.1.0
  foo >= 1.2.3
])

1. If your pkg-config file is not on the pkg-config path, you can augment the pkg-config search path by adding a line just before the call to PKG_CHECK_MODULES:

export PKG_CONFIG_PATH=/custom/path:$PKG_CONFIG_PATH

Adding a Library Directly

To add a library, edit the Makefile.am file in your component's implementation directory.

1. Open the Makefile.am file in your component's implementation directory.

2. Append compiler and linker flags to the end of the CXXFLAGS and LDADD lines, respectively. For example:

   MyComponent_CXXFLAGS += -I/usr/local/include/foo
   MyComponent_LDADD += -L/usr/local/lib64 -lfoo