Re: [Boost-users] Is there a boost way to avoid this macro usage?

13 Oct 2005

      Paul Mensonides wrote:
...
...
That's pretty cool. I'm going to impose on your good nature 
to ask a follow up question here. In the real code, each CODE 
macro contains more entries, like so:
#define CODE_TABLE \
 CODE(FooCodeA, "FooCodeA short description", 
"SummarySelectorFooCodeA", "DetailSelectorFooCodeA") \
 CODE(FooCodeB, "FooCodeB short description", 
"SummarySelectorFooCodeB", "DetailSelectorFooCodeB")
And the structure is defined as:
typedef struct
{
   CodesT   theCode;
   const char *pTheCodeAsString;
   const char *pShortDescription;
   const char *pSummarySelector;
   const char *pDetailSelector;
} CodeLookupTableT;
I have done no programming with the preprocessor lib, so I 
only have a vague idea how to extend what you did to cover 
this case. (I think CODE needs to define either an array or a 
list or a sequence or a tuple, but that's as far as I have
gotten...) Would
you be willing to give it a go?
Certainly.  You just need a have a data structure of data structures.  You don't
really need CODE at all.
--------------------
foo.h
--------------------
#include 
#include 
#include 
#define CODE_TABLE \
   ( (FooCodeA, "description", "summary", "detail") ) \
   ( (FooCodeB, "description", "summary", "detail") ) \
   /**/
#define ENUM(r, _, i, tuple) \
   BOOST_PP_COMMA_IF(i) BOOST_PP_TUPLE_ELEM(4, 0, tuple) \
   /**/
class foo
{
public:
   typedef enum { BOOST_PP_SEQ_FOR_EACH_I(ENUM, ~, CODE_TABLE) };
// ...
};
#undef ENUM
--------------------
foo.cpp
--------------------
#include "foo.h"
#include 
#include 
#include 
#define ENTRY(r, _, i, tuple) \
   BOOST_PP_COMMA_IF(i) ENTRY_II tuple \
   /**/
#define ENTRY_II(code, desc, summary, detail) \
   { code, BOOST_PP_STRINGIZE(code), desc, summary, detail } \
   /**/
foo::CodeTableLookupT foo::m_lookupTable[]
   = { BOOST_PP_SEQ_FOR_EACH_I(ENTRY, ~, CODE_TABLE) }
#undef ENTRY
#undef ENTRY_II
Note that I'm using an extra ENTRY_II macro here to avoid five invocations of
BOOST_PP_TUPLE_ELEM.
<snipped>

That. Is. So. Cool! No inner macros to redefine, and you can wrap the 
enum declaration in a macro that takes CODE_TABLE (or whatever the 
developer calls it) as a parameter. Same for the array definition. This 
is a big improvement on the original version. Thank you for the great help.

I was unfamiliar with Chaos, but the code snippets looked interesting. I 
found the project on SourceForge. Will there be a release sometime?

Thanks again,
Rush

Re: [Boost-users] Is there a boost way to avoid this macro usage?

Rush Manbert