Hello,<div><br></div><div>I&#39;ll try to illustrate what I am trying to do on this example:<br><div><br></div><div><div>#define VER 1</div><div><br></div><div>// given alternative sets of macros:</div><div>#if VER==1</div>

<div>#define M0()</div><div>#define M1( arg0 )</div><div>#define M2( arg0, arg1 )</div><div>#define M3( arg0, arg1, arg2 )</div><div>#define M4( arg0, arg1, arg2, arg3 )</div><div>#elif VER==2</div><div>#define V0( x )</div>

<div>#define V1( x, arg0 )</div><div>#define V2( x, arg0, arg1 )</div><div>#define V3( x, arg0, arg1, arg2 )</div><div>#define V4( x, arg0, arg1, arg2, arg3 )</div><div>#endif</div><div><br></div><div>// I&#39;m trying to write alternative versions of INVOKE for the above sets of macros,</div>

<div>// so that the interface below needs no #ifs</div><div>#if VER==1</div><div>#define INVOKE( n_args ) \</div><div>    BOOST_PP_CAT(M,n_args)( BOOST_PP_ENUM_PARAMS(n_args,arg) )</div><div>#elif VER==2</div><div>#define INVOKE( n_args ) \</div>

<div>    BOOST_PP_CAT(V,n_args)( dummy BOOST_PP_ENUM_TRAILING_PARAMS(n_args,arg) )</div><div>#endif</div><div><br></div><div>// the interface implemented in terms of INVOKE</div><div>#define A0() INVOKE(0)</div><div>#define A1( arg0 ) INVOKE(1)</div>

<div>#define A2( arg0, arg1 ) INVOKE(2)</div><div>#define A3( arg0, arg1, arg2 ) INVOKE(3)</div><div>#define A4( arg0, arg1, arg2, arg3 ) INVOKE(4)</div><div><br></div><div>int main()</div><div>{</div><div><span class="Apple-tab-span" style="white-space:pre">	</span>A2(1,2)</div>

<div>}</div></div></div><div><br></div><div>My goal here is to keep INVOKE as simple and non-redundant as possible, because alternative versions of INVOKE for alternative sets of given macros will be added later on.</div>

<div><br></div><div>Now the call A2(1,2) doesn&#39;t compile. If I understand correctly, the reason is ENUM_PARAMS(n_args,arg) is passed to M2, while I need the result of macro expansion of ENUM_PARAMS(...)  to be passed to M2. So my question is: Is there a way around this?</div>

<div><br></div><div>I attached a file ready to compile with the presented code.</div><div><br></div><div>Thanks in advance</div><div>Kris</div>