Understanding FindCABLE in CMake Modules

Purpose

• It assists in integrating CABLE with your CMake project by automatically determining the paths to necessary files:
  • CABLE executable (CABLE)
  • CABLE Tcl wrapper library (CABLE_TCL_LIBRARY)
  • CABLE include directory (CABLE_INCLUDE_DIR)
• The FindCABLE module is a CMake script designed to locate an installed CABLE library on your system.

Functionality

1. • The module starts by verifying if CABLE information is already cached from a previous build (NOT CABLE).
   • If a cache exists (CABLE_BUILD_DIR), it loads the cached data, potentially saving time on repeated searches.

2. Extracting Information from Cache (if build directory is found)
   

   • If the build directory is located, the script retrieves the following from the cache:
     • CABLE_LIBRARY_PATH: Path to CABLE libraries
     • CABLE_EXECUTABLE_PATH: Path to the CABLE executable
     • CABLE_INCLUDE_DIR: Path to CABLE include files

3. Finding CABLE Library (if cache info is missing)
   

   • If cache information or the build directory is unavailable, the script searches for the CABLE Tcl wrapper library (CableTclFacility) in the following locations (in order):
     • Paths specified in CABLE_LIBRARY_PATH (if set)
     • Standard library locations relative to the build directory

4. Finding CABLE Executable (if library is not found in cache)
   

   • If the library search fails, the script looks for the CABLE executable (cable) in system paths.

5. Deriving Include Directory (if executable is found)
   

   • Once the CABLE executable is located, the script deduces the path to the include directory based on a relative path assumption (refer to the source code for details).

6. Setting Variables
   

   • After successful searches, the script sets the following CMake variables:
     • CABLE: Path to the CABLE executable
     • CABLE_TCL_LIBRARY: Path to the CABLE Tcl wrapper library
     • CABLE_INCLUDE_DIR: Path to the CABLE include directory

How to Use

1. Include the Module
   

   • In your CMakeLists.txt file, include the FindCABLE module using the find_package command:

   find_package(CABLE REQUIRED)
   

2. Link Libraries and Use Include Directory
   

   • During project configuration, CMake will use the variables set by FindCABLE to link your project against the CABLE libraries and include the necessary headers from the CABLE_INCLUDE_DIR.

---

cmake_minimum_required(VERSION 3.0)
project(MyCABLEProject)

# Try to find CABLE using the FindCABLE module
find_package(CABLE REQUIRED)

# Include CABLE headers
include_directories(${CABLE_INCLUDE_DIR})

# Create a simple executable that uses CABLE
add_executable(my_cable_program main.cpp)

# Link against CABLE libraries
target_link_libraries(my_cable_program ${CABLE_TCL_LIBRARY})

1. CMake Minimum Required Version
   This line specifies the minimum CMake version required to build this project.
2. Project Declaration
   project(MyCABLEProject) declares the project name.
3. Find CABLE
   
   • find_package(CABLE REQUIRED) attempts to locate CABLE using the FindCABLE module. The REQUIRED keyword indicates that your project depends on CABLE and cannot proceed without it.
4. Include CABLE Headers
   
   • include_directories(${CABLE_INCLUDE_DIR}) adds the CABLE include directory to your project's include paths. This will allow your code to access CABLE header files.
5. Create Executable
   
   • add_executable(my_cable_program main.cpp) defines an executable named my_cable_program that will be built from the source file main.cpp.
6. Link Libraries
   
   • target_link_libraries(my_cable_program ${CABLE_TCL_LIBRARY}) instructs CMake to link the built executable (my_cable_program) against the CABLE Tcl wrapper library (CABLE_TCL_LIBRARY). This ensures that your code can access CABLE functionality during execution.

• You may need to modify the linking step depending on the specific libraries provided by CABLE. Consult the CABLE documentation for details.
• Replace main.cpp with your actual source file that uses CABLE functionality.

---

1. • If CABLE provides a pkg-config file, you can use CMake's pkg_search_module to locate it programmatically:

   pkg_search_module(CABLE REQUIRED)
   
   # Access CABLE variables set by pkg_search_module
   include_directories(${CABLE_INCLUDE_DIR})
   target_link_libraries(my_cable_program ${CABLE_LIBRARIES})  # May differ depending on CABLE
   

   • This approach leverages the existing pkg-config system on your machine for CABLE discovery, potentially offering wider compatibility. However, it requires CABLE to provide the necessary pkg-config file.