[CMake] configure_file - false vs "0"

[James C. Sutherland]

>>>
>>> Aah, now I see what you want...
>>>
>>> #define TEST_VAR_VALUE ${TEST_VAR_VALUE}
>>>
>>> is what you want.
>>
>>
>> But if I do
>> set( TEST_VAR_VALUE 0 )
>> then this results in TEST_VAR_VALUE being undefined rather than  
>> having the value of 0 as I want.  If the value is anything other  
>> than zero it works.  This is what I tried to explain in my original  
>> (probably unclear) post...
>>
>
> $ cat CMakeLists.txt
> cmake_minimum_required( VERSION 2.6 )
> project( test )
> set( TEST_VAR_VALUE1 0 )
> set( TEST_VAR_VALUE2 1 )
> set( TEST_VAR_VALUE3 "hello there" )
> configure_file( config.h.in ${test_BINARY_DIR}/config.h )
>
> $ cat config.h.in
> #define TEST_VAR_VALUE1 ${TEST_VAR_VALUE1}
> #define TEST_VAR_VALUE2 ${TEST_VAR_VALUE2}
> #define TEST_VAR_VALUE3 ${TEST_VAR_VALUE3}
>
> $ mkdir build && cd build && cmake ..
> $ cat config.h
> #define TEST_VAR_VALUE1 0
> #define TEST_VAR_VALUE2 1
> #define TEST_VAR_VALUE3 hello there
>
>
> Which presumably is what you want... why would you think that  
> SET(TEST_VAR_VALUE 0) "undefines" it? For that you either use  
> SET(TEST_VAR_VALUE), or with newer versions of CMake you can use the  
> clearer UNSET(TEST_VAR_VALUE).
>
>
> Michael

Thank you and Bill for your patience and help.  Indeed, I  
misunderstood the "#define" vs "#cmakedefine" in the config.h.in  
file.  This now works.

BTW, although I am somewhat new to build systems, I find cmake to be a  
very nice tool - definitely much simpler to use than autoconf!  I also  
dabbled with bjam and find cmake more usable (and the fact that it  
supports F90 is great).

Thanks again for the help.