CMake/Modules/FindPackageMessage.cmake

# FIND_PACKAGE_MESSAGE(<name> "message for user" "find result details")
#
# This macro is intended to be used in FindXXX.cmake modules files.
# It will print a message once for each unique find result.
# This is useful for telling the user where a package was found.
# The first argument specifies the name (XXX) of the package.
# The second argument specifies the message to display.
# The third argument lists details about the find result so that
# if they change the message will be displayed again.
# The macro also obeys the QUIET argument to the find_package command.
#
# Example:
#
#  if(X11_FOUND)
#    FIND_PACKAGE_MESSAGE(X11 "Found X11: ${X11_X11_LIB}"
#      "[${X11_X11_LIB}][${X11_INCLUDE_DIR}]")
#  else()
#   ...
#  endif()

#=============================================================================
# Copyright 2008-2009 Kitware, Inc.
#
# Distributed under the OSI-approved BSD License (the "License");
# see accompanying file Copyright.txt for details.
#
# This software is distributed WITHOUT ANY WARRANTY; without even the
# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
# See the License for more information.
#=============================================================================
# (To distribute this file outside of CMake, substitute the full
#  License text for the above reference.)

function(FIND_PACKAGE_MESSAGE pkg msg details)
  # Avoid printing a message repeatedly for the same find result.
  if(NOT ${pkg}_FIND_QUIETLY)
    string(REGEX REPLACE "[\n]" "" details "${details}")
    set(DETAILS_VAR FIND_PACKAGE_MESSAGE_DETAILS_${pkg})
    if(NOT "${details}" STREQUAL "${${DETAILS_VAR}}")
      # The message has not yet been printed.
      message(STATUS "${msg}")

      # Save the find details in the cache to avoid printing the same
      # message again.
      set("${DETAILS_VAR}" "${details}"
        CACHE INTERNAL "Details about finding ${pkg}")
    endif()
  endif()
endfunction()