Aleksey, Many thanks for your detailed reply. I think the second scenario with pre-generated headers convinces me more, since our compilation times are not optimal at all :(. But as you stated in the book: more work for compiler means less work at runtime. These were not exactly the words, but I can remember the meaning. I have one more question: I tried to use the preprocess_map.py script, but encounter some problems. Running it on Windows with Python 2.5 causes the following output: D:\projects\libraries\boost_1_33_0\libs\mpl\preprocessed>preprocess_map.py Usage: preprocess_map.py <mode> <boost_root> [<source_file>] Purpose: updates preprocessed version(s) of the header(s) in "boost\mpl\map\aux_\preprocessed" directory Example: the following command will re-generate and update all 'apply.hpp' headers: preprocess_map.py all f:\cvs\boost apply.cpp How do I submit here the max map size? Or did you mean that I should write a similar script, which pregenerates headers by my own? If I look inside of this script, there is one call to main which passes 3 parameters, but probably this does not work. If I pass parameters as in this example, I get an error that gcc is not installed. Ok, I will install it and put it into my PATH env var, but still the question, how do specify the size of max map? Is there any way to include pre-generated headers for 150 elements into the next boost release? Probably the unnumbered mpl::map template could go until 50 types to save compilation time, but if someone wishes to go above, he/she could use numbered map templates like map150. The problem, why I am going to suggest it, is that if someone pre-generates the header and updates the version, it is possibly, that pre-generated headers will be removed and project maintainer (not usually programmer who generated these headers) will suddenly get compiler errors and will have to repeat this procedure again. And some other question: Dave said, that mpl::map had some bug fixes from the 1.33 release to upcoming 1.34. Will these preprocessing scripts break the changes? Many thanks for your effort and time, Ovanes -----Original Message----- From: Aleksey Gurtovoy [mailto:agurtovoy@meta-comm.com] Sent: Saturday, November 04, 2006 3:29 AM To: boost-users@lists.boost.org Cc: Ovanes Markarian; dave@boost-consulting.com Subject: Re: [mpl::map] generating map for 150 types Hi Ovanes,
I need to define a map with int_<1...150>->Type1...150 pairs.
Im source file I define:
#define BOOST_MPL_CFG_NO_PREPROCESSED_HEADERS #define BOOST_MPL_LIMIT_MAP_SIZE 150
#include <boost/mpl/map.hpp>
A word of caution: redefining BOOST_MPL_LIMIT_MAP_SIZE is not recommended. Doing so globally will make you pay for what you probably don't use (unless all present and future 'map' usages in your project demand the 150-elements limit), and doing so within a translation unit will lead to an ODR violation. If you need to construct a sequence beyond the default size, use its numbered form (http://www.boost.org/libs/mpl/doc/refmanual/variadic-sequence.html).
When compiling I get an error in the file: ...\boost\include\boost-1_33_1\boost\mpl\map.hpp on line: 36 fatal error C1083: Cannot open include file: 'boost/mpl/map/map150.hpp': No such file or directory
Development environment is Visual C++ 8 Express Edition
The help states:
[...] What the BOOST_MPL_LIMIT_MAP_SIZE docs don't say is that there is a default upper limit of 50 elements for the macro's value: #define BOOST_MPL_CFG_NO_PREPROCESSED_HEADERS #define BOOST_MPL_LIMIT_MAP_SIZE 50 #include <boost/mpl/map.hpp> // compiles This upper limit is overridable as well, but since touching BOOST_MPL_LIMIT_MAP_SIZE is not recommended anyway, I'll instead demonstrate how to bump the number of map's numbered forms up to 150. The simpliest way would be just this: #include <boost/mpl/map/map50.hpp> #include <boost/preprocessor/iterate.hpp> namespace boost { namespace mpl { # define BOOST_PP_ITERATION_PARAMS_1 \ (3,(51, 150, <boost/mpl/map/aux_/numbered.hpp>)) # include BOOST_PP_ITERATE() }} // use map150<....> with the caveat that the extra 100 map templates are generated on the fly using the preprocessor, which isn't ideal from the compilation time standpoint. Alternatively, you can pre-generate these extra templates once and for all using the '$BOOST_ROOT/libs/mpl/preprocessed/preprocess_map.py' script and the existing numbered map files in the '$BOOST_ROOT/boost/mpl/map/' and '$BOOST_ROOT/libs/mpl/preprocessed/map/' subdirectories as an example. HTH, -- Aleksey Gurtovoy MetaCommunications Engineering