[vtk-developers] Errors in building VTKExamples in today's CVS

[Bill Lorensen]

Brad,

BTW, for the tests themselves I am using the vtk test framework, so
that only one executable per kit is generated for testing. That works
great.

On Mon, Dec 21, 2009 at 10:27 AM, Bill Lorensen <bill.lorensen at gmail.com> wrote:
> Brad,
>
> In my local build I have modified the Examples/Foo/Cxx files to do this:
>
> IF(NOT VTK_BINARY_DIR)
> FIND_PACKAGE(VTK REQUIRED)
> ENDIF(NOT VTK_BINARY_DIR)
>
> This seems to let me build outside of the VTK tree. Doesn't this
> simple approach work OK?
>
> Also, since one can build with examples off, the solution can be kept
> small if one desires it to be small.
>
> Bill
>
> On Mon, Dec 21, 2009 at 9:49 AM, Brad King <brad.king at kitware.com> wrote:
>> Dave Partyka wrote:
>>> Bill Lorensen wrote:
>>>> I'm revamping the Examples tree. As part of that I hope to remove the
>>>> complexity of the current CMakeLists.txt file. I'm not sure why there
>>>> is a need for the custom command to build the examples. The current
>>>> method makes it very difficult to add tests to the examples.
>>> I think the intention there was so that you could build the examples
>>> against an installed vtk, though I guess that doesn't make sense as we
>>> no longer ship libraries, just vtk.exe? I am CC'ing Brad King and Dave
>>> Cole  as I remember one of them describing this to me a while back. I
>>> agree though, that whole CMakeLists.txt is probably more complex than
>>> necessary.
>>
>> There are multiple reasons for the current approach:
>>
>> (1) The Examples directory has many executables, which if included in
>>    the main VTK build crowd VS solution files.
>>
>> (2) The Examples tree, along with each individual example, should build
>>    as a stand-alone project against the build or install tree.
>>
>> (3) Since the Examples tree must always support building as an outside
>>    project, it is best to keep this well-tested by *always* building
>>    it that way.
>>
>> As to the current implementation that meets the above requirements:
>>
>> (a) The only way to build the Examples tree as an outside project but
>>    also build it as part of VTK is to drive the outside project with
>>    a custom target.
>>
>> (b) The current complexity in the Examples/CMakeLists.txt file is left
>>    from old versions of CMake whose language was much weaker.
>>
>> Implementation choice (b) is easy to change.  We can fix it by making
>> VTK/Examples a totally standalone directory that CMake never enters as
>> a subdirectory of the main build.  The custom target that drive it now
>> can be moved to a separate directory.
>>
>> Implementation choice (a) is not something we can change.  Before it
>> was done this way we had constant problems with users that were unable
>> to build projects they copied from the examples because they could only
>> build in-tree.
>>
>> Bill, what you seem to want is a new requirement:
>>
>> (4) The Examples tree should have tests that run as part of the main
>>    VTK test suite.
>>
>> Since there is no add_subdirectory() in the main VTK that enters the
>> real Examples build tree, CTestTestfile.cmake does not include the
>> Examples tests.  There are two approaches to solving this problem.
>>
>> (c1) Add a test in the main VTK tree that invokes CTest to run all
>>     tests from the Examples tree.
>>
>> (c2) Use the TEST_INCLUDE_FILE property to include the VTK Examples
>>     test suite in the main VTK test suite:
>>     http://www.cmake.org/cmake/help/cmake2.6docs.html#prop_dir:TEST_INCLUDE_FILE
>>
>> I also have some ideas for more complicated solutions but let's not
>> discuss them if (c1) or (c2) is acceptable.
>>
>> -Brad
>>
>