[Idea] New Command Register Interface

[codehz]

Concept:

CustomCommandResult teleport_to_player(CommandOrigin &origin, ServerPlayer *target) {
// IMPL
}
CustomCommandResult teleport_to_pos(CommandOrigin &origin, Vec3 target) {
// IMPL
}
// register
BDLCommandRegistry.register("teleport", teleport_to_player, teleport_to_pos);

Note: the pattern of the command is CustomCommandResult (*)(CommandOrigin &origin, T... t)

[ghost]

@codehz What about void teleport_to_player(CommandOriginHelper&/Helper class for access to BDS CommandOrigin/ origin,CustomCommandResult& res,ServerPlayer sp){ //origin.getPlayer returns ServerPlayer if(!origin.isPlayer()){ res.error(); res<<"error "<<123<<origin.getName(); //overloaded << operator } } BDLCMDRegistry::registerCommand("tpa",overload1/Infer arguments automatically /,overload2,if_no_overload_found_handler);

[ghost]

@codehz and could you please show how to register a command with enum? like /tpa {accept,deny},etc.

[codehz]

to register enum:

enum class MyEnum: int {A, B};
auto test = BDLCommandRegistry::newEnum<MyEnum>("test");
test.add("A", MyEnum::A);
test.add("B", MyEnum::B);

dynamic enum:

// in global scope
static auto test = BDLCommandRegistry::newDynamicEnum<decltype("test_dynamic"_dynenum)>(); // use gcc extension to generate type from string
// in some function
test.set({"A", "B"});
test.clear();
test.add("C");

and a better command register method:

auto command = BDLCommandRegistry::newCommand("command");
command.add(impl_01);
command.add(impl_02);
command.set_fallback(if_no_overload_found_handler); // I'm not sure if it can be implemented...

[codehz]

maybe we should use codegen insteads of just template meta programming... or the argument name cannot be inferred from function.. (and optional argument)

[ghost]

@codehz yeah,you're right. I wonder whether overload will be called,if no suitable overload is found. like this. /tpa <{to,from}:enum> /tpa <--- will be called when "/tpa wrong usage xxxx"

[codehz]

BTW, the command parsing is happened in server side.. so the malformed command expression would be able to detect in server side and rerouting to fallback handler.. seems pointless..

[ghost]

@codehz using mojang command overload api seems like a morr complex way to solve problem(need to generate class and vtable dynamically(or need a codegen),need to reverse-engineer more api). Use a simple lexer with overload support maybe a better choice? Maybe we can use tricks to make client show overloads,like multi-line command description.(hadnt tested)

[ghost]

@codehz I dont know if duplicated availableCommandsPacket with only one command works well.(it means sending overloads of a mod commands after server sent previous availableCommandsPacket to client ) Modifing availableCommandsPacket::write seems like a difficult job.

[ghost]

@codehz @CodeHz new idea:

void tpa_to_impl(...,ServerPlayer* sp,int xx){

}
CommandBase cmd("tpa");
cmd.overload("to <dest:player> <testval:int>",tpa_to_impl);//use template like overload(string_view,void(*)(...,T ,T2) to determine how many arguments need to be parsed(in base.h) and base.so just exports regCommand0(sview,void *function),regCommand1...,etc..
and lexer parses overload,and do some preparations(convert string to int,ServerPlayer*,etc)
and use (void(*)(...,void*,void*))callback(arg0,arg1,argx)

CONS : 1.assume that all arguments are 64bits long.(so passing string_view and const string(abi:cxx11) cant work?(because string_view uses two registers).And float cant work ad well(because it uses %xmm0 register) ) 2.use a lot of else if to make right calls(right counts of arguments)

[codehz]

alternative concept: for codegen

// header (.h)
struct Teleport : CustomCommandDescription {
static constexpr auto name = "teleport";
static constexpr auto permission = CommandPermission::OP;
// any name
void impl_01(ServerPlayer *target); // generate `teleport <target: player>`
// use std::optional for optional argument
void impl_02(Vec3 pos, std::optional<int> angle);  // generate `teleport <pos: position> [angle: int]`
// use enum
void impl_03(MyEnum target);  // generate `teleport <target: my_enum>`
};
extern "C" {
BDL_EXPORT int mod_register_command(CommandRegistry *); // codegen
}
// impl (.cpp)
void Teleport::impl_01(ServerPlayer *target) {}
....