#define ImplBaseRTTI(classname) RuntimeClass classname::rtti(NULL);
#define ImplRTTI(classname, b1) RuntimeClass classname::rtti(&b1::rtti, NULL)
#define ImplRTTI2(classname, b1, b2) RuntimeClass classname::rtti(&b1::rtti, &b2::rtti, NULL)
#define ImplRTTI3(classname, b1, b2, b3) RuntimeClass classname::rtti(&b1::rtti, &b2::rtti, &b3::rtti, NULL)
#define ImplRTTI4(classname, b1, b2, b3, b4) RuntimeClass classname::rtti(&b1::rtti, &b2::rtti, &b3::rtti, &b4::rtti, NULL)
#define ImplRTTI5(classname, b1, b2, b3, b4, b5) RuntimeClass classname::rtti(&b1::rtti, &b2::rtti, &b3::rtti, &b4::rtti, &b5::rtti, NULL)
#define ImplRTTI6(classname, b1, b2, b3, b4, b5, b6) RuntimeClass classname::rtti(&b1::rtti, &b2::rtti, &b3::rtti, &b4::rtti, &b5::rtti, &b6::rtti, NULL)
#define ImplRTTI7(classname, b1, b2, b3, b4, b5, b6, b7) RuntimeClass classname::rtti(&b1::rtti, &b2::rtti, &b3::rtti, &b4::rtti, &b5::rtti, &b6::rtti, &b7::rtti, NULL)
#define ImplRTTI8(classname, b1, b2, b3, b4, b5, b6, b7, b8) RuntimeClass classname::rtti(&b1::rtti, &b2::rtti, &b3::rtti, &b4::rtti, &b5::rtti, &b6::rtti, &b7::rtti, &b8::rtti, NULL)
我该如何更改此代码，例如
#define ImplRTTI(classname, ...) RuntimeClass classname::rtti(&__VA_ARGS__::rtti, NULL)
如果仅可以将ImplRTTI与此宏一起使用，则此代码不必变得很长或很复杂。
最佳答案
来自foreach-macro-on-macros-arguments
#define PP_NARG(...) PP_NARG_(__VA_ARGS__,PP_RSEQ_N())
#define PP_NARG_(...) PP_ARG_N(__VA_ARGS__)
#define PP_ARG_N( \
_1, _2, _3, _4, _5, _6, _7, _8, _9,_10, \
_11,_12,_13,_14,_15,_16,_17,_18,_19,_20, \
_21,_22,_23,_24,_25,_26,_27,_28,_29,_30, \
_31,_32,_33,_34,_35,_36,_37,_38,_39,_40, \
_41,_42,_43,_44,_45,_46,_47,_48,_49,_50, \
_51,_52,_53,_54,_55,_56,_57,_58,_59,_60, \
_61,_62,_63,N,...) N
#define PP_RSEQ_N() \
63,62,61,60, \
59,58,57,56,55,54,53,52,51,50, \
49,48,47,46,45,44,43,42,41,40, \
39,38,37,36,35,34,33,32,31,30, \
29,28,27,26,25,24,23,22,21,20, \
19,18,17,16,15,14,13,12,11,10, \
9,8,7,6,5,4,3,2,1,0
/* need extra level to force extra eval */
#define Paste(a,b) a ## b
#define XPASTE(a,b) Paste(a,b)
/* APPLYXn variadic X-Macro by M Joshua Ryan */
/* Free for all uses. Don't be a jerk. */
/* I got bored after typing 15 of these. */
/* You could keep going upto 64 (PPNARG's limit). */
#define APPLYX1(a) X(a)
#define APPLYX2(a,b) X(a) X(b)
#define APPLYX3(a,b,c) X(a) X(b) X(c)
#define APPLYX4(a,b,c,d) X(a) X(b) X(c) X(d)
#define APPLYX5(a,b,c,d,e) X(a) X(b) X(c) X(d) X(e)
#define APPLYX6(a,b,c,d,e,f) X(a) X(b) X(c) X(d) X(e) X(f)
#define APPLYX7(a,b,c,d,e,f,g) \
X(a) X(b) X(c) X(d) X(e) X(f) X(g)
#define APPLYX8(a,b,c,d,e,f,g,h) \
X(a) X(b) X(c) X(d) X(e) X(f) X(g) X(h)
#define APPLYX9(a,b,c,d,e,f,g,h,i) \
X(a) X(b) X(c) X(d) X(e) X(f) X(g) X(h) X(i)
#define APPLYX10(a,b,c,d,e,f,g,h,i,j) \
X(a) X(b) X(c) X(d) X(e) X(f) X(g) X(h) X(i) X(j)
#define APPLYX11(a,b,c,d,e,f,g,h,i,j,k) \
X(a) X(b) X(c) X(d) X(e) X(f) X(g) X(h) X(i) X(j) X(k)
#define APPLYX12(a,b,c,d,e,f,g,h,i,j,k,l) \
X(a) X(b) X(c) X(d) X(e) X(f) X(g) X(h) X(i) X(j) X(k) X(l)
#define APPLYX13(a,b,c,d,e,f,g,h,i,j,k,l,m) \
X(a) X(b) X(c) X(d) X(e) X(f) X(g) X(h) X(i) X(j) X(k) X(l) X(m)
#define APPLYX14(a,b,c,d,e,f,g,h,i,j,k,l,m,n) \
X(a) X(b) X(c) X(d) X(e) X(f) X(g) X(h) X(i) X(j) X(k) X(l) X(m) X(n)
#define APPLYX15(a,b,c,d,e,f,g,h,i,j,k,l,m,n,o) \
X(a) X(b) X(c) X(d) X(e) X(f) X(g) X(h) X(i) X(j) X(k) X(l) X(m) X(n) X(o)
#define APPLYX_(M, ...) M(__VA_ARGS__)
#define APPLYXn(...) APPLYX_(XPASTE(APPLYX, PP_NARG(__VA_ARGS__)), __VA_ARGS__)
现在
#define X(b) &b::rtti,
#define ImplBaseRTTI(classname) RuntimeClass classname::rtti(NULL)
#define ImplRTTI(classname, ...) \
RuntimeClass classname::rtti(APPLYXn(__VA_ARGS__) NULL)
关于c++ - C++宏参数，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/45386706/