This macro expands by default to
256. For a C++
standard conforming preprocessor, the end-user can change this to
512 or 1024 by defining this macro to either value before
including any library headers, as long as the end-user also
defines the
BOOST_PP_LIMIT_MAG
macro to be equal to or greater than this value.
NOTE: for the current latest versions of default preprocessor for
Microsoft's VC++ compiler there is a nested macro limit of 256.
This means in actuality that the number of repetitions using VC++
is actually less than 256 depending on the repetition macro being
used. For the BOOST_PP_REPEAT macro this limit appears to be 252
while for the BOOST_PP_ENUM... series of macros this limit appears
to be around 230, before the VC++ compiler gives a "C1009:
compiler limit : macros nested too deeply" error. This is a
compiler limitation of VC++ which may vary depending on the
specific repetition macro being used, and therefore is not a
problem the preprocessor library can solve. This limitation of the
default preprocessor for VC++ does not exist for the new standard
conforming preprocessor for VC++ in Visual Studio 2019 invoked
with the
/Zc:preprocessor switch.