Hi Roman, thanks for your answer. How can do that with MPL? Any pointers? Thanks, Christian On Mon, Dec 7, 2009 at 4:30 AM, Roman Perepelitsa wrote:

2009/12/6 Christian Henning

...

Hi there,

let's assume I have a structure which takes 5 ints as template parameters.

template< int NumChannel        , int FirstChannelBits  = 0        , int SecondChannelBits = 0        , int ThirdChannelBits  = 0        , int FourthChannelBits = 0        , int FifthChannelBits  = 0        > struct pixel_type_generator { /* omitted*/ }

The first parameter is different as it defines how many of the other parameters are actually used.

How can I use boost::preprocessor to get this kind of code repetition:

<cut> FWIW, this can be achieved with Boost.MPL instead of preprocessor. Roman Perepelitsa. _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

On Mon, Dec 7, 2009 at 10:13 PM, Steven Watanabe wrote:

AMDG

This is 248,832 calls. I wouldn't be surprised if this worked out to several million template instantiations. The largest tests that I have run have been less than 50,000 template instantiations. I think you're going to destroy the compiler if you try this.

Steven, but as far as I understand it will destroy the compiler eitherway. Does it really matter if he is going to use preprocessor to generate the code or MPL? Templates are instantiated in both cases... Best Regards, Ovanes

OK OK. I was thinking the same. ;-) For now I would be more than thankful if someone could tell how I can actually accomplish the code using boost::preprocessor or even boost::mpl. This test wont be permanent. I'm trying to nail down issues with gil. Though, I can run in stages. Thanks, Christian On Mon, Dec 7, 2009 at 5:00 PM, Steven Watanabe wrote:

AMDG

Ovanes Markarian wrote:

...

On Mon, Dec 7, 2009 at 10:13 PM, Steven Watanabe wrote:

...

This is 248,832 calls.  I wouldn't be surprised if this worked out to several million template instantiations.  The largest tests that I have run have been less than 50,000 template instantiations.  I think you're going to destroy the compiler if you try this.

but as far as I understand it will destroy the compiler eitherway. Does it really matter if he is going to use preprocessor to generate the code or MPL? Templates are instantiated in both cases...

How is the Preprocessor vs. MPL relevant to what I said? The only way to make it work is to split the tests into many translation units.

In Christ, Steven Watanabe

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Hi there, thanks Steven for your good advise. I have been making some progress but I'm stuck on one part. Here is some code that exhibits my problem. #include template< int i, int j > void test() {} int main() { #define S1 (1)(2)(3) #define S2 (1)(2)(3) #define FOR_EACH( r, data, elem ) BOOST_PP_CAT( elem \ , BOOST_PP_COMMA() ) #define FOR_EACH_PRODUCT(r, product) test< BOOST_PP_SEQ_FOR_EACH( FOR_EACH \ , BOOST_PP_EMPTY() \ , product \ ) >(); BOOST_PP_SEQ_FOR_EACH_PRODUCT( FOR_EACH_PRODUCT \ , (S1)(S2) \ ) return 0; } Here is what the preprocessor produces: test< 1, 1, >(); test< 1, 2, >(); test< 1, 3, >(); test< 2, 1, >(); [snip] My problem is that I cannot figure out how to get rid of the last comma? Any ideas? Thanks, Christian

Wow, thanks Steven. This is exactly what I'm looking for. Although, I find the name BOOST_PP_SEQ_ENUM a bit odd. Everything works now. And yes, there are way too many template instantiations. ;-) Christian On Sun, Dec 13, 2009 at 6:05 PM, Steven Watanabe wrote:

AMDG

Christian Henning wrote:

...

Hi there, thanks Steven for your good advise. I have been making some progress but I'm stuck on one part. Here is some code that exhibits my problem.

#include

template< int i, int j > void test() {}

int main() {    #define S1 (1)(2)(3)    #define S2 (1)(2)(3)    #define FOR_EACH( r, data, elem ) BOOST_PP_CAT( elem \                                                  , BOOST_PP_COMMA() )

   #define FOR_EACH_PRODUCT(r, product) test<  BOOST_PP_SEQ_FOR_EACH( FOR_EACH \                                                                     , BOOST_PP_EMPTY() \                                                                     , product \                                                                     ) >();

   BOOST_PP_SEQ_FOR_EACH_PRODUCT( FOR_EACH_PRODUCT \                                 , (S1)(S2) \                                 )

   return 0; }

Here is what the preprocessor produces:

test< 1, 1,   >(); test< 1, 2,   >(); test< 1, 3,   >(); test< 2, 1,   >(); [snip]

My problem is that I cannot figure out how to get rid of the last comma? Any ideas?

BOOST_PP_SEQ_ENUM?

In Christ, Steven Watanabe

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