c - Let a macro count its invocations -

i've huge c project module reading , managing configuration data. if have add new configuration parameter, i'll have edit several functions, e.g. pseudo-code:

void read_configuration(config *c) {     read_param("p1", c->p1);     read_param("p2", c->p2);     read_param("p3", c->p3);     /* ... */ }  void dump_configuration(config *c) {     dump_param("p1", c->p1);     dump_param("p2", c->p2);     dump_param("p3", c->p3);     /* ... */ } 

is there way ensure macro at compile time, each location has @ least same count of parameters? thought of making dump_param kind of macro counting invocations , add like

#if nr_read != nr_dump     #error "you forgot something, idiot!" #endif 

at end of module. can't find method make macro count invocations, though...

since list of parameters same in both functions, how factoring that out , avoid possible mismatch ?

using x-macros

#define x_config_params(config) \     x("p1", (config).p1)        \     x("p2", (config).p2)        \     x("p3", (config).p3)  void read_configuration(config *c) { #define x(name, param) read_param(name, &param);     x_config_params(*c) #undef x }  void dump_configuration(config *c) { #define x(name, param) dump_param(name, &param);     x_config_params(*c) #undef x } 

using function pointers

void alter_config(config *c, void(*func)(char const *name, param *param)) {     func("p1", &c->p1);     func("p2", &c->p2);     func("p3", &c->p3); }  void read_configuration(config *c) {     alter_config(c, read_param); }  void dump_configuration(config *c) {     alter_config(c, dump_param); } 

using array , offsetof

struct param_info {     char const *name;     size_t config_offs; };  param_info allparams[] = {     {"p1", offsetof(config, p1)},     {"p2", offsetof(config, p2)},     {"p3", offsetof(config, p3)} };  void read_configuration(config *c) {     size_t paramcount = sizeof allparams / sizeof *allparams;     for(size_t = 0; < paramcount; ++i) {         param *p = (param*)((char*)config + allparams[i].config_offs);         read_param(allparams[i].name, p);     } }  void dump_configuration(config *c) {     size_t paramcount = sizeof allparams / sizeof *allparams;     for(size_t = 0; < paramcount; ++i) {         param *p = (param*)((char*)config + allparams[i].config_offs);         dump_param(allparams[i].name, p);     } }