cmake - preset settings for entries from ini file - cmake

Question

I have a project that uses some third party libraries. So each time I setup this project with CMake, I have to set each entry (path of the third party library) on the GUI of CMake. I improve this by making CMake script guess the path by this script (learn this technique from OGRE):
# Guess the paths.
set( OGRE_SOURCE "${CMAKE_CURRENT_SOURCE_DIR}/Dependencies/Ogre" CACHE STRING "Path to OGRE source code (see http://www.ogre3d.org/tikiwiki/tiki-index.php?page=CMake+Quick+Start+Guide)" )
So each time I setup with CMake, it will automatic fill the entry OGRE_SOURCE. But that doesn't enough. If the Ogre source is not in the path
"${CMAKE_CURRENT_SOURCE_DIR}/Dependencies/Ogre"
, then I have to open and edit the CMake script or I have to edit the entry on the GUI of CMake. I find that pretty inconvenient, especially when you link to a lot of third party libraries.
So I want to use another technique: preset settings for entries from file - CMake reads the presets from file PresetEntries.txt (that I make) and apply the these presets on the entries (It's a lot quicker to edit the path in text file than on the GUI of CMake).
Here my idea about this preset file: PresetEntries.txt
OGRE_SOURCE=E:/Source/ogre
I found that CMake can read a text file, but if I use this, I have to do string manipulations.
CMake has the file CMakeCache.txt to save the settings on the CMake GUI, but I want it to be simple: it should only has the preset settings that need to be pre-set.
So I wonder if CMake support this preset settings for entries from file.
Edit:
So I read this question and see that CMake can set config from file, but this require to fire cmake with the -C mysettings.cmake, but I wanna it to be automatically with CMake GUI - just edit the file and hit generate button in CMake GUI. So I wanna make this question more specific:
In my CMakeLists.txt should have script like this:
# Guess the paths.
#I wanna have this function from C++
#https://msdn.microsoft.com/en-us/library/windows/desktop/ms724353%28v=vs.85%29.aspx?f=255&MSPPError=-2147217396
GetPrivateProfileString("OGRE", #lpAppName
"OGRE_SOURCE", #lpKeyName
"${CMAKE_CURRENT_SOURCE_DIR}/Dependencies/Ogre", #lpDefault
OGRE_SOURCE_VAR,#lpReturnedString
MAX_PATH, #nSize, may be can reduce this variable
"LibPath.ini") #lpFileName
set( OGRE_SOURCE "${OGRE_SOURCE_VAR}" CACHE STRING "Path to OGRE source code" )
In the file LibPath.ini
[OGRE]
OGRE_SOURCE = "E:/Source/ogre"
So the user can choose to either use the ini file or not.
I don't know if there any way I can use a function that similar to function GetPrivateProfileString (of C++) in CMake.
Thanks for reading

Answer 1

The external libraries should be included by one of the following commands
find_package(ttnlib REQUIRED HINTS /usr/local/lib/cmake)
include_directories(${ttnlib_INCLUDE_DIR})
set(EXTRA_LIBS ${EXTRA_LIBS} ${TTNLIB_LIBRARY})
or
find_library(MY_EXTERNAL_LIB name COOLSTUFF libCOOLSTUFF libCOOLSTUF.so hints /usr/local/lib)
The search for the external packages and libraries should only be necessary for the first run of cmake.

Answer 2

I can't find the function to read the ini file, so what I can do is create a simple function that read simple txt file for myself.
I declare the function in 1 file for other file use it
"\CMake\Dependencies\CommonFunc.cmake"
#------------Define function Read file------------
macro( readSettingFile KEY DEFAULT_RESULT STRING_RESULT_OUT)
unset(STRING_RESULT)
# Read the file
file( READ "${CMAKE_SOURCE_DIR}/LibPath.txt" LIB_PATH_STR )
# Set the variable "Esc" to the ASCII value 27 - basically something
# which is unlikely to conflict with anything in the file contents.
string(ASCII 27 Esc)
# Turn the contents into a list of strings, each ending with an Esc.
# This allows us to preserve blank lines in the file since CMake
# automatically prunes empty list items during a foreach loop.
string(REGEX REPLACE "\n" "${Esc};" LIB_PATH_LINES "${LIB_PATH_STR}")
foreach(LINE ${LIB_PATH_LINES})
if("${LINE}" MATCHES "${KEY}")
#remove the key, leave the content untouch
string(REPLACE "${KEY}" "" STRING_RESULT ${LINE})
# Swap the appended Esc character back out in favour of a line feed
string(REGEX REPLACE "${Esc}" "" STRING_RESULT ${STRING_RESULT})
endif()
endforeach()
if("${STRING_RESULT}" STREQUAL "")
set( STRING_RESULT ${DEFAULT_RESULT} )
endif()
#message( STATIC "---GTA Sa-----" "[${STRING_RESULT}]" )
endmacro()
(I need the help from this answer to write this function :p)
Here is how I use
For example: "\CMake\Dependencies\Ogre.cmake"
#include common functions
include( CMake/Dependencies/CommonFunc.cmake )
#---------------Guess the paths.----------------------
#----Set OGRE_SOURCE
readSettingFile( "OGRE_SOURCE="
"E:/Source/ogre"
STRING_RESULT
)
set( OGRE_SOURCE "${STRING_RESULT}" CACHE STRING "Path to OGRE Source" )
#----Set OGRE_BINARIES
readSettingFile( "OGRE_BINARIES="
"E:/Source/_build/ogre"
STRING_RESULT
)
set( OGRE_BINARIES "${STRING_RESULT}" CACHE STRING "Path to OGRE's build folder generated by CMake" )
Here is the setting file
"\LibPath.txt"
OGRE_SOURCE=E:/Source/ogre
OGRE_BINARIES=E:/Source/_build/ogre