[boost] Autolinking when an autolinked function/class is never used

From: Edward Diener (eldiener_at_[hidden])
Date: 2008-07-11 17:02:51

I think it is an error when an end-user uses a Boost library which may 
need a separate DLL built, never uses a function/class which is 
implemented in that separate DLL, and yet the Boost header files for 
that library bring in autolinking. Is this considered an error in the 
development of a Boost library ?

What is invariably happening when this situation occurs is that a header 
file which has autolinking code ( #pragma comment(lib,"somelib") in VC++ 
for example ) is included for functions/classes which are not in the 
autolinked library at all. This is because the Boost developer has not 
placed all the autolinked functionality for a particular library in its 
own header file, preferring instead to place declarations in logically 
related header files. While the latter is understandable as far as 
organization of a library is concerned it destroys the ability of that 
library to enforce autolinking only when the end-user requires it.

Despite the fact that library developers, of Boost libraries which are 
not completely header only, go for orthogonality when creating their 
header files I would like to see things changed so that using a library 
which does not require the built library to be linked in when using 
functionality of that library does not being in autolinking. I realize 
that there are macros of the BOOST_SOMELIB_NO_LIB around to turn off 
autolinking but this places a burden on the end user which should not be 
there.

I was recently using the date/time library for the first time, used 
functionality which I was pretty sure was not in the built library based 
on the documentation, yet autolinking code was brought in to force me as 
an end-user to specify the location of the import library. When I 
defined BOOST_DATE_TIME_NO_LIB in my project settings, everything linked 
fine without specifying the import library, so obviously the DLL was not 
needed. Nobody wants to distribute a shared library with their code when 
it is unnecessary.