Add slic macros that only log the first time they're called

[kennyweiss]

A discussion in #1683 prompted the question about adding slic macros that only log/warn the first time they're encountered.

I'd suggest adopted something like the following (based on code that @tomstitt wrote a few years ago):

#define SLIC_INFO_ONCE_IF(cond, msg) \
   do                               \
   {                                \
      static bool once = true;      \
      if (cond)                     \
      {                             \
         if (once)                  \
         {                          \
            SLIC_INFO(msg);          \
            once = false;           \
         }                          \
      }                             \
   } while (false)

#define SLIC_INFO_ONCE(msg) SLIC_INFO_ONCE_IF(true, msg)

#define SLIC_INFO_ONCE_ROOT_IF(cond, msg) \
   do                                    \
   {                                     \
      static bool once = true;           \
      if (cond)                          \
      {                                  \
         if (once)                       \
         {                               \
            SLIC_INFO_ROOT(msg);          \
            once = false;                \
         }                               \
      }                                  \
   } while (false)

#define SLIC_INFO_ONCE_ROOT(msg) SLIC_INFO_ONCE_ROOT_IF(true, msg)

We should also add similar macros for warnings and possibly debug.

[rhornung67]

I think would be generally useful. I recommend using the current macro names and appending _ONCE to them for this rather. This would make it easy for users to apply them without having to look up specific macro names beyond what they are already using. The examples you posted are not uniform in this respect.

[jcs15c]

When implemented, these methods will be particularly useful in

• NURBSPatch.hpp during parameter space evaluation methods.
• intersect_patch_impl.hpp if excessive intersections are recorded.