我使用的是SML（https://boost-ext.github.io/sml/）v.1.1.3，我需要访问注入的依赖项和操作中的状态机。根据下面的提交，这应该已经工作了：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
在接下来的示例中，我尝试访问action2中的依赖项和sm，但得到了一个编译错误：

sml.hpp:1853:18: note:   cannot convert ‘deps’ (type ‘boost::ext::sml::v1_1_3::aux::pool<int, {anonymous}::actions_guards&, {anonymous}::actions_guards>’) to type ‘int&’  1853 |     return object(event, sm, deps, subs);

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:   required from ‘bool boost::ext::sml::v1_1_3::back::sm_impl< <template-parameter-1-1> >::process_event(const TEvent&, TDeps&, TSubs&) [with TEvent = {anonymous}::e2; TDeps = boost::ext::sml::v1_1_3::aux::pool<int, {anonymous}::actions_guards&, {anonymous}::actions_guards>; TSubs = boost::ext::sml::v1_1_3::aux::pool<boost::ext::sml::v1_1_3::back::sm_impl<boost::ext::sml::v1_1_3::back::sm_policy<{anonymous}::actions_guards> > >; TSM = boost::ext::sml::v1_1_3::back::sm_policy<{anonymous}::actions_guards>]’
/usr/local/oecore-x86_64_tux_dunfell/sysroots/armv5te-angstrom-linux-gnueabi/usr/include/boost/sml.hpp:1660:81:   required from ‘bool boost::ext::sml::v1_1_3::back::sm< <template-parameter-1-1> >::process_event(const TEvent&) [with TEvent = {anonymous}::e2; typename boost::ext::sml::v1_1_3::aux::enable_if<boost::ext::sml::v1_1_3::aux::integral_constant<bool, __is_base_of(TEvent, boost::ext::sml::v1_1_3::back::sm::events_ids)>::value, int>::type <anonymous> = 0; TSM = boost::ext::sml::v1_1_3::back::sm_policy<{anonymous}::actions_guards>]’
main.cpp:86:23:   required from here
/usr/local/oecore-x86_64_tux_dunfell/sysroots/armv5te-angstrom-linux-gnueabi/usr/include/boost/sml.hpp:1853:18: error: no match for call to ‘(boost::ext::sml::v1_1_3::aux::zero_wrapper<{anonymous}::<lambda(const auto:3&, auto:4&, int&, std::string&)>, void>) (const {anonymous}::e2&, boost::ext::sml::v1_1_3::back::sm_impl<boost::ext::sml::v1_1_3::back::sm_policy<{anonymous}::actions_guards> >&, boost::ext::sml::v1_1_3::aux::pool<int, {anonymous}::actions_guards&, {anonymous}::actions_guards>&, boost::ext::sml::v1_1_3::aux::pool<boost::ext::sml::v1_1_3::back::sm_impl<boost::ext::sml::v1_1_3::back::sm_policy<{anonymous}::actions_guards> > >&)’
 1853 |     return object(event, sm, deps, subs);
      |            ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
main.cpp:37:16: note: candidate: ‘template<class auto:3, class auto:4> {anonymous}::<lambda(const auto:3&, auto:4&, int&, std::string&)>’
   37 | auto action2 = [](const auto& event, auto& sm, int& i, std::string& str) {
      |                ^
main.cpp:37:16: note:   template argument deduction/substitution failed:
In file included from main.cpp:20:
/usr/local/oecore-x86_64_tux_dunfell/sysroots/armv5te-angstrom-linux-gnueabi/usr/include/boost/sml.hpp:1853:18: note:   cannot convert ‘deps’ (type ‘boost::ext::sml::v1_1_3::aux::pool<int, {anonymous}::actions_guards&, {anonymous}::actions_guards>’) to type ‘int&’
 1853 |     return object(event, sm, deps, subs);
      |            ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~