10 ms·

after #define if(X) LET(_it,X) if (_it) it would be a macro call

• yoklov 13y ago
  I'm fairly certain that shadowing a keyword with a macro is forbidden by the standard (or invokes UB?) but this will still work for most compilers, provided LET is defined reasonably. Hm, something like #define LET(name, X) \ for (int let_once_=1, name=(X); \ let_once_; \ let_once_=0) may be reasonable, though tokenpasting in __LINE__ for good measure might be necessary for nesting.
  • 30thElement 13y ago
    Shadowing keywords is perfectly valid, although I believe you can't shadow keywords in standard headers so that compiler writers don't need to worry about it. It gives rise to some "useful" C/C++ features that should never be used, like if you want to access private members in foo.cpp, do #define private public #include "foo.cpp" #undef private
    • TazeTSchnitzel 13y ago
      I can imagine some insidious menace adding this to the top of a file: #define public protected
      • yoklov 13y ago
        I once someone jokingly do (the second only always works in C, not C++) #define else #define struct union Evil!