[vtk-developers] Plan to make CMake 3.3 and C++11 required

[Robert Maynard]

Hi,

I believe that the VTK object reference counting model is not well
suited to a transition to c++11 shared pointer design. It would
require a redesign of how everyone constructs VTK classes ( New,
ShallowCopy, etc ) with no clear gain. VTK already uses an atomic ref
count, and we don't need the shared_ptr overhead of holding the
destructor.

I do see value in VTK providing pre-made destructors for
std::shared_ptr, etc so that you can safely mix the two different
types of reference counting.

On Mon, Jan 16, 2017 at 4:47 PM, Alexis Girault
<alexis.girault at kitware.com> wrote:
> Awesome! Will there be any interest to transition to the c++11 smart
> pointers (shared, weak, unique)?
>
> Alexis
>
> On Mon, Jan 9, 2017 at 5:18 PM, Robert Maynard <robert.maynard at kitware.com>
> wrote:
>>
>> We have merged in the branch to require CMake 3.3 today. So I will be
>> keeping an eye on the dashboard machines and updating machines over
>> the next couple of days.
>>
>> I also expect to have a MR open end of this week that will explicitly
>> enable C++11 with a goal to have that merged in on Monday Jan 16.
>>
>> On Wed, Jan 4, 2017 at 2:06 PM, Robert Maynard
>> <robert.maynard at kitware.com> wrote:
>> > As we start a new year, it is time to announce that we are planning on
>> > rolling out a series of updates to VTK that are starting with the update
>> > of the minimum required CMake version.
>> >
>> > We have chosen CMake 3.3 as the minimum required version for numerous
>> > reasons,
>> > the most important of those reasons being:
>> >
>> > - It is the first CMake release that offers C++11 support for all four
>> > major
>> >   compilers ( GCC / MSVC / Clang / XCode ). [1]
>> >
>> > - The CMake version is sufficiently new enough that it allows for a
>> > cleaning
>> >   of the existing CMake infrastructure. The current CMake minimum
>> > version
>> >   requires VTK to maintain forks of numerous FindPackages and Modules
>> > that are
>> >   part of newer CMake versions.
>> >
>> > - Supports HTTPS downloads, with all the official binaries come with
>> > support.
>> >   Allowing for migration of external data to a HTTPS only server.
>> > Something we
>> >   are going to require in the near future. [2]
>> >
>> > As mentioned above this year we have a series of upgrades planned to VTK
>> > which
>> > require moving the minimum CMake version to 3.3. The most significant
>> > of these changes to all developers is the requirement of a C++11 capable
>> > compiler.
>> >
>> > Yes you heard that correct, VTK is going to soon require a C++11 capable
>> > compiler. To be more exact we are going to require a compiler that
>> > understands
>> > the significant majority of the C++11 language and runtime additions.
>> > The exact
>> > versions for each compiler have not been set in stone, but a rough
>> > estimation
>> > would be:
>> >   - GCC 4.8+
>> >   - Clang 3.3+
>> >   - XCode 5.0+
>> >   - MSVC 2013+
>> > As we progress through the year, I expect a more concrete list of
>> > supported
>> > compilers will be determined and documented.
>> >
>> > Now the roll out for C++11 support is going to happen in multiple stages
>> > with an initial plan being:
>> >
>> > Stage 1: We require CMake 3.3, upgrade all dashboards, work through
>> > developer
>> >          reported issues with the version bump
>> >
>> > Stage 2: Explicitly enable C++11 compiler flags during CMake
>> > configuration. Again
>> >          we will have to upgrade/retire dashboards, work through
>> > developer
>> >          reported issues.
>> >
>> > Stage 3: Update the VTK Coding Standards for C++11.
>> >
>> > Stage 4: Allow C++11 to be used in VTK ( outside currently permitted
>> > usage ).
>> >
>> > Notes:
>> >
>> > 1 - If you are using a different compiler vendor than one of those
>> > listed above
>> >     please see if it is currently supported
>> >     (
>> > https://cmake.org/cmake/help/v3.7/manual/cmake-compile-features.7.html ).
>> >     If the vendor is not explicitly listed please contact me, so we can
>> > discuss
>> >     what options are available.
>> >
>> > 2 - https://data.kitware.com is transitioning to be the location for all
>> >     external data, and requires a SSL connection.
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>