Macro BOOST_VMD_ASSERT_IS_EMPTY

BOOST_VMD_ASSERT_IS_EMPTY — Asserts that the input is empty.

Synopsis

// In header: <boost/vmd/assert_is_empty.hpp>

BOOST_VMD_ASSERT_IS_EMPTY(...)

Description

The macro checks to see if the input is empty or not. If it is not empty, it forces a compiler error.

The macro is a variadic macro taking any input. For the VC++8 compiler (VS2005) the macro takes a single parameter of input to check and not variadic data.

The macro normally checks for emptiness only in debug mode. However an end-user can force the macro to check or not check by defining the macro BOOST_VMD_ASSERT_DATA to 1 or 0 respectively.

.... = variadic input, for VC++8 this must be a single parameter.

returns = Normally the macro returns nothing. 

          If the input is empty, nothing is output.
          
          For VC++, because there is no sure way of forcing  
          a compiler error from within a macro without producing
          output, if the input is not empty the 
          macro forces a compiler error by outputting invalid C++.
          
          For all other compilers a compiler error is forced 
          without producing output if the input is not empty.

It is recommended to append BOOST_PP_EMPTY() to whatever input is being tested in order to avoid possible warning messages from some compilers about no parameters being passed to the macro when the input is truly empty.

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