On 1. Sep, 2009, at 4:12, j s wrote:
According to Microsoft, the math macros are not part of standard C/C+
+:
http://msdn.microsoft.com/en-us/library/4hwaceh6(VS.80).aspx
I'm not going to quibble with them on that point, as they were nice
enough
to provided them with:
_USE_MATH_DEFINES
as an alternative. The problem is the config.h approach is I now
have to
include a config.h everywhere I want to use a math macro. Even
worse is if
I put all my platform dependent options in that file. If I put an
unrelated
macro change in that file, I just retriggered a rebuild for many
files not
requiring a rebuild. The potential for triggering unnecessary
rebuilds
anytime that file is regenerated is just not worth it.
I will quibble with Microsoft that Visual Studio does not detect
when the
compilation options change.
Regards,
Juan
On Mon, Aug 31, 2009 at 8:45 PM, Philip Lowman <phi...@yhbt.com>
wrote:
On Mon, Aug 31, 2009 at 8:02 PM, j s <j.s4...@gmail.com> wrote:
I am doing cross-platform compilation. I don't want everything to
recompile on all platforms. That is a risk with having a
configuration
header file. If I remember correctly, cmake would ignore
conditional
include guards when doing dependency scanning. Therefore:
#ifdef WIN32
#include "config.hh"
#endif
would trigger a compilation on all platforms if config.hh changed.
I want everything to recompile on Windows, but not on my linux
builds.
I think when he meant a config file he meant one created by CMake
dynamically (which would only affect one build anyways).
In other words:
config.h.in:
#cmakedefine FOO
CMakeLists.txt:
set(FOO true)
configure_file(${CMAKE_CURRENT_SOURCE_DIR}/config.h.in
${CMAKE_CURRENT_BINARY_DIR}/config.h)
include_directories(${CMAKE_CURRENT_BINARY_DIR})
config.h now includes "#define FOO 1"
Of course if all you need is the "unborkify MSVC so it supports
math.h"
define then it's probably not worth it. :)
--
Philip Lowman
How about doing it like this:
compat_math.h:
------>8------
#ifndef COMPAT_MATH_H
#define COMPAT_MATH_H
#ifdef WIN32
#define _USE_MATH_DEFINES 1
#endif
#include <math.h>
#endif
------<8------
And then replace all includes of math.h by compat_math.h. Of course,
as soon as you 'touch' that file, you will trigger a lot of
recompilations. But the effects can be reduced by only including
compat_math.h in implementation files.
Michael
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