How to understand the below macros in the code - c++

Question

I am trying to understand the code base of an application but having issue in interpreting the below macros. Would any one please help me in understanding the code below.
#define LIST_OF_AP_COMMANDS(ENTRY) \
ENTRY(WLAN_AP_SET_IP, 2, (WEP_MODE | WPA_MODE | NONE_MODE), "ifconfig wlan1 %s > /dev/null", abAPIpAddress) \
ENTRY(WLAN_AP_REMOVE_NETWORK, 2, (WEP_MODE | WPA_MODE | NONE_MODE), "wpa_cli -iwlan1 remove_network 0 > /dev/null") \
ENTRY(WLAN_AP_ADD_NETWORK, 2, (WEP_MODE | WPA_MODE | NONE_MODE), "wpa_cli -iwlan1 add_network > /dev/null") \
ENTRY(WLAN_AP_SET_SSID, 2, (WEP_MODE | WPA_MODE | NONE_MODE), "wpa_cli -iwlan1 set_network 0 ssid '\"%s\"' > /dev/null", CON_acbSSID) \
ENTRY(WLAN_AP_SET_PASS, 2, (WPA_MODE), "wpa_cli -iwlan1 set_network 0 psk '\"%s\"' > /dev/null", CON_acPassword) \
ENTRY(WLAN_AP_SET_PASSWORD, 2, (WEP_MODE | WPA_MODE | NONE_MODE), "wpa_cli -iwlan1 set_network 0 key_mgmt %s > /dev/null", pcSecurityTypes[CON_bSecurityType] ) \
ENTRY(WLAN_AP_SET_FREQUENCY, 2, (WEP_MODE | WPA_MODE | NONE_MODE), "wpa_cli -iwlan1 set_network 0 frequency %d > /dev/null", CON_awWifiFreqs[ CON_bChannel ]) \
ENTRY(WLAN_AP_SET_MODE, 2, (WEP_MODE | WPA_MODE | NONE_MODE), "wpa_cli -iwlan1 set_network 0 mode 2 > /dev/null") \
ENTRY(WLAN_AP_SET_MODE, 2, WEP_MODE , "wpa_cli -iwlan1 set_network 0 wep_key0 %s > /dev/null", CON_acPassword) \
ENTRY(WLAN_AP_SET_MODE, 2, WEP_MODE , "wpa_cli -iwlan1 set_network 0 wep_tx_keyidx 0 > /dev/null") \
ENTRY(WLAN_AP_ENABLE_NETWORK, 10, (WEP_MODE | WPA_MODE | NONE_MODE), "wpa_cli -iwlan1 enable_network 0 > /dev/null" )
//! Expander with the execution of each command
#define EXECUTE_WLAN_COMMANDS(index, delay, mode, command, ...) \
if( ( abSecurityModes[CON_bSecurityType] & mode ) ) { CON_cExecuteWlanCommand(command, ##__VA_ARGS__); } else { printf("wpa_cli %d %d\r\n", abSecurityModes[CON_bSecurityType], mode); } \
sleep( delay );

Answer 1

X-macros are a traditional technique for handling code generation in languages which use macro preprocessors like the C/C++ preprocessor. The idea is that you have a list of elements -- types, enumeration constants, message strings, etc. -- and you need to use that list more than once in order to generate your code.fir example, you might want to make both a list of error messages and an enum which defines symbolic names for each error. Or perhaps you have several different structures and you need to make two or more specific functions for each structure. (In C++, you would probably use templates for this particular case.)
The name "X-macro" comes from the original pattern in which the list macro invoked a macro with a given name -- by convention X -- on each element of the list, leading to a pattern like:
#define X(name, value) … // some use of name and value
HANDLE_LIST
#undef X
#define X(name, value) … // sone other use
HANDLE_LIST
#undef X
// etc.
But at some point, it became much more common to use a list-handler which takes the name of the macro to call as an argument (a so-called "higher order macro"). This allows for more meaningful names and avoids to need to repeatedly undefine X. (Particularly useful if you have miore than one list.)
And that's what you are seeing here.