Add cmake_utils feature to set a library minimum version (#10)

Signed-off-by: jparisu <javierparis@eprosima.com>

Signed-off-by: jparisu <javierparis@eprosima.com>

Author: jparisu

cmake_utils/README.md

@@ -30,6 +30,8 @@ In order to compile a C++ library, use the following macros:
 1. To compile tests for the library: `compile_test(${<test path>})`
 1. To install the package following eprosima defaults `eprosima_packaging()`
 
+---
+
 ## Module Requirements
 
 In order create a package (called Module from now on) using this library,
@@ -49,8 +51,9 @@ The version will be loaded from this file if it is not set in `project_settings.
 
 Every module requires to have a `LICENSE` file in order to install it with the result of the module.
 
+---
 
-#### Project using cmake_utils variables
+## Project configuration using cmake_utils variables
 
 These are the variables that could/must be set in the `project_settings.cmake` file.
 Those variables which default is `x` must be set, and those with `-` are not required.
@@ -87,7 +90,21 @@ Those variables which default is `x` must be set, and those with `-` are not req
 |------------------------------|-------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------|
 | MODULE_CPP_VERSION           | C++17                                                                   | C++ version                                                                                        |
 
-#### Project using cmake_utils CMake options
+### Minimum Package Version
+
+Setting the CMake variable `<library>_MINIMUM_VERSION` will force the `find_package` call to look for library
+`<library>` with minimum version `${<library>_MINIMUM_VERSION}`.
+
+e.g.
+
+```cmake
+set(MODULE_FIND_PACKAGES fastrtps)
+set(fastrtps_MINIMUM_VERSION "2.8")  # This will force to use a version of fastrtps higher or equal 2.8
+```
+
+---
+
+## Project using cmake_utils CMake options set
 
 There are default CMake options used within cmake_utils package that will always be set.
 In case the user sets these variables, they will have that value. Otherwise,

cmake_utils/cmake/cpp_common/find_external.cmake

@@ -20,11 +20,28 @@
 #
 # ARGUMENTS:
 # - EXTERNAL_PROJECT_NAMES: List of names of external projects to find
+#
+# If ${${EXTERNAL_PROJECT}_MINIMUM_VERSION} is set for any of the project names passed as argument, it will
+# be used in order to look for a minimum version for this package.
+#
+
 macro(find_external_projects EXTERNAL_PROJECT_NAMES)
 
     foreach(EXTERNAL_PROJECT ${EXTERNAL_PROJECT_NAMES})
-        find_package("${EXTERNAL_PROJECT}" REQUIRED)
-        message(STATUS "Package ${EXTERNAL_PROJECT} found")
+        # Check if this project requires a minimum version, set as ${EXTERNAL_PROJECT}_MINIMUM_VERSION
+        if (${${EXTERNAL_PROJECT}_MINIMUM_VERSION})
+
+            find_package("${EXTERNAL_PROJECT}" "${${EXTERNAL_PROJECT}_MINIMUM_VERSION}" REQUIRED)
+            message(
+                STATUS
+                "Package ${EXTERNAL_PROJECT} found higher than minimum version ${EXTERNAL_PROJECT}_MINIMUM_VERSION")
+
+        else()
+
+            find_package("${EXTERNAL_PROJECT}" REQUIRED)
+            message(STATUS "Package ${EXTERNAL_PROJECT} found")
+
+        endif()
     endforeach()
 
     # Finish macro