Insane Dependencies

[nobody]

From: helvey@accelrys.com

Simply including boost/date_time/posix_time headers causes build times to skyrocket. Building a file that includes boost/date_time/posix_time/posix_time.hpp takes almost a minute, removing the header drops the time to less than a second.
Also why no conversions to time_t? It would be nice not to have include the header outside of translation units. :)

[az_sw_dude]

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Well, nothing even close on my Linux machine:

time g++-4.0 -I /opt/devTools/boost_rc_1_34 test.cpp

real    0m1.482s
user    0m1.140s

//test.cpp
#include "boost/date_time/posix_time/posix_time.hpp"

int main()
{

  return 0;
}

**************
That said, I agree that header isn't particularly "light weight" -- it does include a large number of files.  Some of this could be paired down by removing depedence on lexical_cast and shared_ptr in the core library.  Neither of these are quick changes to make.

As for time_t conversion, please submit that as an independent feature request, but be aware that there are many dates/times that will cause an exception on this conversion since there are many dates/time boost date-time can represent that time_t cannot.

Thx,

Jeff

[Andrey Semashev]

I suspect most of the compilation overhead is due to IO support code, which aside from streams uses quite a few heavy things, such as lexical_cast and Boost.StringAlgo. It would be really great to move as much of this code to the compiled library as possible.

[Andrey Semashev]

Request for conversions to time_t extracted to #3132.

[Marshall Clow]

Is this still a useful request? Here's what I got on my MacBookPro (junk is just 'main', junk2 includes "boost/date_time/posix_time/posix_time.hpp")

DuoTwo:~ marshall$ time g++ -I /Marshall/Sources/boost/trunk junk.cpp

real 0m0.056s user 0m0.025s sys 0m0.023s

DuoTwo:~ marshall$ time g++ -I /Marshall/Sources/boost/trunk junk2.cpp

real 0m1.641s user 0m1.395s sys 0m0.228s

[Andrey Semashev]

I think, it is useful. Boost.DateTime is included from other libraries, such as Boost.Thread. Now it brings in quite a few other dependencies, such as Boost.StringAlgo and Boost.LexicalCast. I think, making Boost.DateTime headers as lightweight as possible is a good thing.

One solution I have in mind is extracting as much IO code as possible into the compiled binary. However, I have other thoughts on optimizing IO that I wanted to implement during the extraction. But these tasks can be done independently.