问题描述
我正在使用SML（https://boost-ext.github.io/sml/）v.1.1.3，需要在操作中访问注入的依赖项和状态机。 根据以下提交，这应该已经起作用：https://github.com/boost-ext/sml/commit/e6d0685993a8a0160dde1610d7f8be4f811c89d0 此提交是此问题的结果： https://github.com/boost-ext/sml/issues/94
在下面的示例中，我尝试在action2中访问依赖项和sm时，出现编译错误：
...
sml.hpp：1853：18：注意：无法转换'deps'（类型'boost :: ext :: sml :: v1_1_3 :: aux :: pool
示例：
#include <boost/sml.hpp>
#include <cassert>
#include <iostream>
namespace sml = boost::sml;
namespace {
struct e1 {};
struct e2 {};
struct e3 {};
auto action2 = [](const auto& event,auto& sm,int& i,std::string& str) {
assert(42 == i);
std::cout << "action2" << std::endl;
std::cout << "sm.n: " << sm.n << std::endl;
};
struct actions_guards {
using self = actions_guards;
int n = 10;
auto operator()() {
using namespace sml;
auto action1 = [](auto e) { std::cout << "action1: " << typeid(e).name() << std::endl; };
auto guard1 = [](int i) {
assert(42 == i);
std::cout << "guard2" << std::endl;
return false;
};
return make_transition_table(
// Start Event Guard Action Next
//+-------------+-------------------+---------------------------+-------------------------------+-------------------------------+
*"idle"_s + event<e1> [ guard1 ] / action1 = "s1"_s,"s1"_s + event<e2> [ &self::guard2 ] / action2 = "s2"_s,"s2"_s + event<e3> = X
);
}
bool guard2(int i) const noexcept {
assert(42 == i);
std::cout << "guard3" << std::endl;
return true;
}
};
} // namespace
int main( int argc,char* argv[] )
{
actions_guards ag{};
std::string strDep( "127.0.0.1" );
int intDep = 42;
sml::sm<actions_guards> sm{ag,intDep,strDep};
sm.process_event(e1{});
sm.process_event(e2{});
sm.process_event(e3{});
assert(sm.is(sml::X));
return 0;
}
错误：
...
sml.hpp：1340：10：从'bool boost :: ext :: sml :: v1_1_3 :: back :: sm_impl :: process_event（const TEvent＆，TDeps＆，TSubs＆）中需要[with TEvent = {anonymous} ::: e2; TDeps = boost :: ext :: sml :: v1_1_3 :: aux :: pool
解决方法
第#399期末，SML作者的答案：
此功能的实现已更改，以避免递归调用并符合UML-2.5
示例
s1 + event<e1> / [](sml::back::process<e2,e3> processEvent) -> void {
processEvent(e2{});
processEvent(e3{});
}
定义sm时必须指定process_queue
sml::sm<c,sml::process_queue<std::queue>> sm{};
这是我实际问题的改编示例：
#include <iostream>
#include <cassert>
#include <queue>
#include <boost/sml.hpp>
namespace sml = boost::sml;
struct e1 {};
struct e2 {};
struct e3 {};
struct my_dep {
int val = 0;
};
auto action = [](sml::back::process<e2,e3> processEvent,my_dep& dep) {
if (dep.val == 0) {
processEvent(e2{});
++dep.val;
}
else
processEvent(e3{});
};
struct table {
auto operator()() const noexcept {
using namespace sml;
return make_transition_table(
*"s1"_s + event<e1> / action = "s3"_s,"s1"_s + event<e2> = "s2"_s,"s3"_s + event<e2> = "s4"_s,"s3"_s + event<e3> = "s5"_s,"s4"_s + event<e1> = "s1"_s
);
}
};
int main() {
using namespace sml;
my_dep md;
sm<table,sml::process_queue<std::queue>> sm{md};
sm.process_event(e1{});
assert(sm.is("s4"_s));
sm.process_event(e1{});
assert(sm.is("s1"_s));
sm.process_event(e1{});
assert(sm.is("s5"_s));
}