Multiple fruit::Assisted arguments and registerFactory caused NoBindingFoundError of std::function

[yuqian90]

I'm trying to evaluate if i can use fruit for something production. Either I'm using fruit::Assisted wrongly or there's a bug somewhere with registerFactory or Assisted.

When the constructor of a class has multiple Assisted arguments. Compilation fails with an error like this:

fruit::impl::NoBindingFoundError<std::function<std::unique_ptr<di::TransientMultiplier>(std::basic_string<char>, int)> >’:

To reproduce the error, create a simple class like this:

class Transient
{
public:
    virtual const int getId() const = 0;

    virtual const std::string getName() const = 0;
};

And create a dependent class like this:

class TransientMultiplier
{
private:
    const Transient& transient;
    std::string suffix;
    int index;

public:
    TransientMultiplier(const Transient& transient, const std::string suffix,
        const int index)
        :transient(transient), suffix(suffix), index(index)
    {

    }

    virtual const std::string getSuffixed()
    {
        std::ostringstream ss;
        ss << transient.getName() << suffix << index;
        return ss.str();
    }
};

TransientMultiplier needs an injected Transient& in its constructor. suffix and index are value types that are supposed to be passed at runtime so they are marked as Assisted

typedef std::function<std::unique_ptr<TransientMultiplier>(std::tuple<const std::string, const int>)> TransientMultiplierFactory;

fruit::Component<fruit::Required<Transient>, TransientMultiplierFactory> getTransientMultiplierFactoryComponent()
{
    using fruit::Assisted;

    return fruit::createComponent()
        .registerFactory
            <std::unique_ptr<TransientMultiplier>(Transient* t,
                Assisted<const std::string>, Assisted<const int>)>
        (
            [](Transient* transient, const std::string suffix, const int index)
            {
                return std::unique_ptr<TransientMultiplier>(
                    new TransientMultiplier(*transient, suffix, index));
            }
        );
}

This looks okay to me. But it does not compile, with a NoBindingFoundError that looks very confusing.

In file included from /usr/include/fruit/fruit.h:25:0,
                 from ../di/Transient.cpp:2:
/usr/include/fruit/impl/injection_errors.h: In instantiation of ‘struct fruit::impl::NoBindingFoundError<std::function<std::unique_ptr<di::TransientMultiplier>(std::basic_string<char>, int)> >’:
/usr/include/fruit/impl/component.defn.h:58:3:   required from ‘fruit::Component<Types>::Component(fruit::PartialComponent<Bindings ...>) [with Bindings = {fruit::impl::RegisterFactory<std::unique_ptr<di::TransientMultiplier, std::default_delete<di::TransientMultiplier> >(di::Transient*, fruit::Assisted<const std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, fruit::Assisted<const int>), di::getTransientMultiplierFactoryComponent()::__lambda16>}; Params = {fruit::Required<di::Transient>, std::function<std::unique_ptr<di::TransientMultiplier, std::default_delete<di::TransientMultiplier> >(std::basic_string<char, std::char_traits<char>, std::allocator<char> >, int)>}]’
../di/Transient.cpp:126:9:   required from here
/usr/include/fruit/impl/injection_errors.h:33:3: error: static assertion failed: No explicit binding nor C::Inject definition was found for T.
   static_assert(
   ^
In file included from /usr/include/fruit/component.h:498:0,
                 from /usr/include/fruit/fruit.h:28,
                 from ../di/Transient.cpp:2:
/usr/include/fruit/impl/component.defn.h: In instantiation of ‘fruit::Component<Types>::Component(fruit::PartialComponent<Bindings ...>) [with Bindings = {fruit::impl::RegisterFactory<std::unique_ptr<di::TransientMultiplier, std::default_delete<di::TransientMultiplier> >(di::Transient*, fruit::Assisted<const std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, fruit::Assisted<const int>), di::getTransientMultiplierFactoryComponent()::__lambda16>}; Params = {fruit::Required<di::Transient>, std::function<std::unique_ptr<di::TransientMultiplier, std::default_delete<di::TransientMultiplier> >(std::basic_string<char, std::char_traits<char>, std::allocator<char> >, int)>}]’:
../di/Transient.cpp:126:9:   required from here
/usr/include/fruit/impl/component.defn.h:61:3: error: no type named ‘Result’ in ‘fruit::impl::meta::OpForComponent<fruit::impl::RegisterFactory<std::unique_ptr<di::TransientMultiplier, std::default_delete<di::TransientMultiplier> >(di::Transient*, fruit::Assisted<const std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, fruit::Assisted<const int>), di::getTransientMultiplierFactoryComponent()::__lambda16> >::ConvertTo<fruit::impl::meta::Comp<fruit::impl::meta::Vector<fruit::impl::meta::Type<di::Transient> >, fruit::impl::meta::Vector<fruit::impl::meta::Type<std::function<std::unique_ptr<di::TransientMultiplier, std::default_delete<di::TransientMultiplier> >(std::basic_string<char, std::char_traits<char>, std::allocator<char> >, int)> > >, fruit::impl::meta::Vector<fruit::impl::meta::Pair<fruit::impl::meta::Type<std::function<std::unique_ptr<di::TransientMultiplier, std::default_delete<di::TransientMultiplier> >(std::basic_string<char, std::char_traits<char>, std::allocator<char> >, int)> >, fruit::impl::meta::Vector<fruit::impl::meta::Type<di::Transient> > > >, fruit::impl::meta::Vector<>, fruit::impl::meta::EmptyList> > {aka struct fruit::impl::meta::Error<fruit::impl::NoBindingFoundErrorTag, std::function<std::unique_ptr<di::TransientMultiplier, std::default_delete<di::TransientMultiplier> >(std::basic_string<char, std::char_traits<char>, std::allocator<char> >, int)> >}’
   (void)typename fruit::impl::meta::CheckIfError<fruit::impl::meta::Eval<fruit::impl::meta::CheckNoLoopInDeps(typename Op::Result)>>::type();
   ^
In file included from /usr/include/fruit/component.h:498:0,
                 from /usr/include/fruit/fruit.h:28,
                 from ../di/Transient.cpp:2:
/usr/include/fruit/impl/component.defn.h:64:15: error: no match for call to ‘(Op {aka fruit::impl::meta::Error<fruit::impl::NoBindingFoundErrorTag, std::function<std::unique_ptr<di::TransientMultiplier, std::default_delete<di::TransientMultiplier> >(std::basic_string<char, std::char_traits<char>, std::allocator<char> >, int)> >}) (fruit::impl::ComponentStorage&)’
   Op()(storage);
               ^

I can go around the problem by putting suffix and index in a std::tuple<string, int>. But that's very inconvenient. So can we not put multiple fruit::Assisted arguments in the same constructor of a class that's going to be binded via registerFactory?

I'm using libfruit Version: 2.0.0-0 on Ubuntu 14.04 installed from this deb:
deb http://download.opensuse.org/repositories/home:/poletti_marco/xUbuntu_14.04/ /

[yuqian90]

Well, I played with factory and ASSISTED a bit more and I'm now more certain there's a bug somewhere.
E.g. I just slightly modified this example from the fruit test source code: tests/register_factory.cpp:

The following would not compile. I guess it's related to my issue.

#include <fruit/fruit.h>
#include <iostream>

using fruit::Component;
using fruit::Injector;
using fruit::Assisted;
using fruit::createComponent;

struct X {
  INJECT(X()) = default;
};

class Scaler {
private:
  double factor;
  int factor2;

public:
  INJECT(Scaler(ASSISTED(double) factor, ASSISTED(int) factor2, X))
    : factor(factor), factor2(factor2) {
  }

  double scale(double x) {
    return x * factor * factor2;
  }
};

using ScalerFactory = std::function<std::unique_ptr<Scaler>(double, int)>;

Component<ScalerFactory> getScalerComponent() {
  return createComponent();
}

int main() {
  Injector<ScalerFactory> injector(getScalerComponent());
  ScalerFactory scalerFactory(injector);
  std::unique_ptr<Scaler> scaler = scalerFactory(12.1, 3);
  std::cout << scaler->scale(3) << std::endl;

  return 0;
}

Compilation error:

In file included from /usr/include/fruit/fruit.h:25:0,
                 from ../di/RegisterFactoryTest.cpp:1:
/usr/include/fruit/impl/injection_errors.h: In instantiation of ‘struct fruit::impl::FunctorSignatureDoesNotMatchError<Scaler(double, int), Scaler(int, double)>’:
/usr/include/fruit/impl/component.defn.h:58:3:   required from ‘fruit::Component<Types>::Component(fruit::PartialComponent<Bindings ...>) [with Bindings = {}; Params = {std::function<std::unique_ptr<Scaler, std::default_delete<Scaler> >(double, int)>}]’
../di/RegisterFactoryTest.cpp:31:26:   required from here
/usr/include/fruit/impl/injection_errors.h:214:3: error: static assertion failed: Unexpected functor signature (it should be the same as ExpectedSignature minus any Assisted types).
   static_assert(
   ^
In file included from /usr/include/fruit/component.h:498:0,
                 from /usr/include/fruit/fruit.h:28,
                 from ../di/RegisterFactoryTest.cpp:1:
/usr/include/fruit/impl/component.defn.h: In instantiation of ‘fruit::Component<Types>::Component(fruit::PartialComponent<Bindings ...>) [with Bindings = {}; Params = {std::function<std::unique_ptr<Scaler, std::default_delete<Scaler> >(double, int)>}]’:
../di/RegisterFactoryTest.cpp:31:26:   required from here
/usr/include/fruit/impl/component.defn.h:61:3: error: no type named ‘Result’ in ‘fruit::impl::meta::OpForComponent<>::ConvertTo<fruit::impl::meta::Comp<fruit::impl::meta::Vector<>, fruit::impl::meta::Vector<fruit::impl::meta::Type<std::function<std::unique_ptr<Scaler, std::default_delete<Scaler> >(double, int)> > >, fruit::impl::meta::Vector<fruit::impl::meta::Pair<fruit::impl::meta::Type<std::function<std::unique_ptr<Scaler, std::default_delete<Scaler> >(double, int)> >, fruit::impl::meta::Vector<> > >, fruit::impl::meta::Vector<>, fruit::impl::meta::EmptyList> > {aka struct fruit::impl::meta::Error<fruit::impl::FunctorSignatureDoesNotMatchErrorTag, Scaler(double, int), Scaler(int, double)>}’
   (void)typename fruit::impl::meta::CheckIfError<fruit::impl::meta::Eval<fruit::impl::meta::CheckNoLoopInDeps(typename Op::Result)>>::type();
   ^
In file included from /usr/include/fruit/component.h:498:0,
                 from /usr/include/fruit/fruit.h:28,
                 from ../di/RegisterFactoryTest.cpp:1:
/usr/include/fruit/impl/component.defn.h:64:15: error: no match for call to ‘(Op {aka fruit::impl::meta::Error<fruit::impl::FunctorSignatureDoesNotMatchErrorTag, Scaler(double, int), Scaler(int, double)>}) (fruit::impl::ComponentStorage&)’
   Op()(storage);
               ^

[poletti-marco]

Thanks for the report, it was indeed a bug.
I'm releasing version 2.0.1 soon with this fix.

[poletti-marco]

FYI, I now released 2.0.1 with this fix and the binary packages have been updated. Please update to get the fix.

[yuqian90]

I gave 2.0.1 a try. It indeed fixed the problem. Thanks a lot!

[poletti-marco]

Now 2.0.2 has been released with the fix to the other related bug.