Re: [boost] Cmake

Subject: Re: [boost] Cmake
From: Robert Ramey (ramey_at_[hidden])
Date: 2017-06-24 21:15:49

On 6/24/17 1:18 PM, Edward Diener via Boost wrote:
> On 6/24/2017 2:53 PM, Robert Ramey via Boost wrote:
>> On 6/24/17 11:42 AM, Edward Diener via Boost wrote:

>> dependencies A.cpp -> dependent libraries for application A
>> dependencies B.cpp -> dependent libraries for application B
> 
> How is a library supposed to know what your application needs 

Right it can't.  That is my point.

One cannot say that the date/time library dependent upon the 
serialization library just because it includes some of the serialization 
library headers.  You can't say that any time the date/time is used the 
serialization library has to be included as well.  You have to wait 
until you see the final application to know whether the part of 
date/time you actually used includes the serialization library.

There seems to be an idea that one can build library dependencies 
automatically by recurrsively scanning the source code #include files. 
This examples shows why this cannot be done.  Dependency outside of a 
particular application is undefined.

? That is  not its responsibility. Doesn't CMake allow manipulation of 
what an
> application needs at some higher level ? When I have used CMake to build 
> LLVM/Clang it certainly allowed me to choose what I wanted for my 
> particular build even though LLVM/CLang provide a whole slew of 
> CMakeLists.txt files. 

If we cannot setup CMake pretty easily for Boost
> libraries so that the end-user can manipulate builds and tests for his 
> needs our CMake setup will be worthless.

LOL - I'm sure we can do it manually.  That's what I do.  What we can't 
do is build date/time ahead of time before we know the application. 
This topic originally came up in the discussion of boost tools bcm? 
which automatically build a dependency tree.

Robert Ramey