Re: [Boost-users] BOOST_PP_COUNTER compiler errors (MSVC8)

From: Robert Dailey (rcdailey_at_[hidden])
Date: 2007-12-20 17:10:25

I think I found the issue. It seems that you can't use the # symbol inside
of macros without it being treated as a preprocessor operator. I don't know
of any way to escape the # character to be treated as part of the macro
code. Is there a way I can increment the counter without doing the #include
statement? Perhaps there is a different implementation of a counter
somewhere that utilizes templates?

Thanks.

On Dec 20, 2007 3:51 PM, Robert Dailey <rcdailey_at_[hidden]> wrote:

> Hi,
>
> I'm currently compiling my code in Visual Studio 2005. Below is the code
> that utilizes BOOST_PP_COUNTER. Note that the goal here is to increment the
> counter 1 time each time the CHECK_MATCH_AND_RETURN macro is used. This
> allows me to make sure that I've got one macro call per enumeration member.
> The problem I'm having is that I'm getting page after page of compiler error
> and as far as I can tell I'm using the counter system as it was shown in the
> code examples. Below I've also listed some of the compiler errors I'm
> getting:
>
> Compiler Errors:
> error C2162: expected macro formal parameter
> error C2065: 'include' : undeclared identifier
> error C2882: 'boost' : illegal use of namespace identifier in expression
>
>
> Code:
>
> #include <boost/static_assert.hpp>
> #include <boost/preprocessor/slot/counter.hpp>
>
> /// Various camera actions that may be performed.
> /// These actions are usually a result of input events.
> enum CameraAction
> {
>       MOVE_FORWARD = 0
>     , MOVE_BACKWARD
>     , MOVE_LEFT
>     , MOVE_RIGHT
>     , MOVE_UP
>     , MOVE_DOWN
>     , ROTATE_RIGHT
>     , ROTATE_LEFT
>     , ROTATE_UP
>     , ROTATE_DOWN
>     , ROLL_LEFT
>     , ROLL_RIGHT
>     , INCREASE_ACCEL
>     , DECREASE_ACCEL
>     , ENABLE_LOOK
>     , TOGGLE_LOOK
>     , ENABLE_AUTO_MOVE
>     , TOGGLE_AUTO_MOVE
>
>     /// @cond
>     , NUM_CAMERAACTIONS
>     , CAMERAACTION_NONE
>     /// @endcond
> };
>
>
> //=========================================================================================
> CameraAction StringToCameraAction( const std::string& str )
> {
>     // I'm using a macro here because I need the stringizing preprocessor
> operator (#)
>     // to make the conditionals more manageable. By using this macro, I
> never have to explicitly
>     // update the string comparison itself if the enumeration names ever
> change.
>     #define CHECK_MATCH_AND_RETURN( action ) if( str == #action ) { return
> action; } #include BOOST_PP_UPDATE_COUNTER()
>
>     CHECK_MATCH_AND_RETURN( ROTATE_LEFT )
>     CHECK_MATCH_AND_RETURN( ROTATE_RIGHT )
>     CHECK_MATCH_AND_RETURN( ROTATE_UP )
>     CHECK_MATCH_AND_RETURN( ROTATE_DOWN )
>     CHECK_MATCH_AND_RETURN( MOVE_UP )
>     CHECK_MATCH_AND_RETURN( MOVE_DOWN )
>     CHECK_MATCH_AND_RETURN( MOVE_LEFT )
>     CHECK_MATCH_AND_RETURN( MOVE_RIGHT )
>     CHECK_MATCH_AND_RETURN( MOVE_FORWARD )
>     CHECK_MATCH_AND_RETURN( MOVE_BACKWARD )
>     CHECK_MATCH_AND_RETURN( ROLL_RIGHT )
>     CHECK_MATCH_AND_RETURN( ROLL_LEFT )
>     CHECK_MATCH_AND_RETURN( INCREASE_ACCEL )
>     CHECK_MATCH_AND_RETURN( DECREASE_ACCEL )
>     CHECK_MATCH_AND_RETURN( ENABLE_LOOK )
>     CHECK_MATCH_AND_RETURN( TOGGLE_LOOK )
>     CHECK_MATCH_AND_RETURN( ENABLE_AUTO_MOVE )
>     CHECK_MATCH_AND_RETURN( TOGGLE_AUTO_MOVE )
>
>     // This helps me remember to add/remove items above.
>     BOOST_STATIC_ASSERT( (BOOST_PP_COUNTER)+1 != NUM_CAMERAACTIONS );
>
>     return CAMERAACTION_NONE;
> }
>