Re: [boost] Cmake

Subject: Re: [boost] Cmake
From: Stefan Seefeld (stefan_at_[hidden])
Date: 2017-06-24 16:22:17

On 24.06.2017 12:08, Gary Furnish via Boost wrote:
> On Sat, Jun 24, 2017 at 9:57 AM, Stefan Seefeld via Boost
> <boost_at_[hidden]> wrote:
>> On 24.06.2017 04:59, Peter Dimov via Boost wrote:
>>> There is considerable interest in Boost supporting CMake, but it seems
>>> that everyone has different ideas as to what this support will entail.
>>> After deliberation and discussions, I have identified the following
>>> (separate) scenarios:
>> I'm a bit confused by the listing, as you use the term "user" in quite
>> different ways.
>>
>>> 1. The user installs a Boost release as usual with `b2 install`, which
>>> makes the installation visible to CMake and usable via
>>> find_package(boost_libname).
>>>
>>> 2. The user brings several Boost libraries as git submodules into his
>>> CMake-based project and uses add_subdirectory in his CMakeLists.txt to
>>> link to them.
>>>
>>> 3. The user uses CMake to install an individual Boost library, which
>>> is then available for find_package.
>>>
>>> 4. The user uses CTest to run the tests of an individual Boost library.
>>>
>>> 5. CMake is supported as a way to build and install the entire Boost,
>>> in place of b2.
>>>
>>> 6. CTest is supported as a way to run the tests for the entire Boost,
>>> in place of b2.
>> All but 1) are addressed at boost developers, i.e. people who want to
>> build (, test, etc.) boost itself. Only 1) is concerned about users who
>> want to use boost as external dependency to their own project.
>>
>>> At the moment, I think that we should concentrate on (1) and (2) as
>>> providing most bang for the buck.
>> To be honest, I don't quite understand 2). Why do you want to support
>> building boost (or parts of it) as an integral part of something else ?
>> Modularity and encapsulation doesn't seem to have any value to you, or
>> does it ?
>>
> As good as modularity and encapsulation sound they make it very hard
> to test code.
Huh ? Test what code ? As a boost user I want to test *my* code, not
boost. (Of course, that doesn't prevent me from also playing the role of
a boost developer / tester, but that are two very different things.

>   Even different distributions sometimes patch packages
> of the same version the same without anyway to detect this.  If you
> don't build boost as part of your program you can't certify its bug
> free with tests.  And forget certification of bug free between
> different versions of boost!
Yeah, now we are plainly in the discussion of Boost's lack of API and
ABI stability.

>   It is simply not an option to rely on
> external libraries when stuff must test clean.
I strongly disagree. Rigorous testing (which includes the clear
distinction between unit testing and integrated testing) doesn't
invalidate encapsulation. Quite the opposite !

>   What mechanism you use
> to do this various but modularity and encapsulation are a dream.

Very sad, but luckily doesn't reflect my experience.

        Stefan

-- 
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