[Boost].DI: C++14 Dependency Injection Library
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kris-jusiak and krzysztof-jusiak πŸ› [MSVC-2017] Workaround for compile error, Fix #344
Problem:
- MSVC-2017 can't compile nested variadic expansion with template aliases.

Solution:
- Use a struct instead of an alias.
Latest commit 57659cf Aug 28, 2018

README.md

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[Boost].DI

Your C++14 one header only Dependency Injection library with no dependencies (Try it online!)

Quick start

Download

[Boost].DI requires only one file. Get the latest header here!

Include

#include <boost/di.hpp>
namespace di = boost::di;

Compile

  • GCC/Clang
    $CXX -std=c++14 -O2 -fno-exceptions -fno-rtti -Wall -Werror -pedantic-errors file.cpp
  • MSVC
    cl /std:c++14 /Ox /W3 file.cpp

Quick guide - Create object graph

class ctor {
public:
  explicit ctor(int i) : i(i) {}
  int i;
};

struct aggregate {
  double d;
};

class example {
  example(aggregate a, const ctor& c) {
    assert(87.0 == a.d);
    assert(42 == c.i);
  };
};

int main() {
  const auto injector = di::make_injector(
    di::bind<int>.to(42),
    di::bind<double>.to(87.0)
  );

  injector.create<example>();
}

Clang-3.8 GCC-6 MSVC-2015
Compilation Time 0.102s 0.118s 0.296s
Binary size (stripped) 6.2kb 6.2kb 105kb
ASM x86-64

xor eax, eax
retq
      

Quick guide - Bind interfaces

struct interface {
  virtual ~iworld() noexcept = default;
  virtual int get() const = 0;
};

class implementation : public interface {
public:
  int get() const override { return 42; }
};

struct example {
  example(std::shared_ptr<interface> i) {
    assert(42 == i->get());
  }
};

int main() {
  const auto injector = di::make_injector(
    di::bind<interface>.to<implementation>()
  );

  injector.create<std::unique_ptr<example>>();
}

Clang-3.8 GCC-6 MSVC-2015
Compilation Time 0.102s 0.118s 0.296s
Binary size (stripped) 6.2kb 6.2kb 105kb
ASM x86-64 (same as `make_unique`)

push   %rbx
mov    %rdi,%rbx
mov    $0x8,%edi
callq  0x4008e0 <_Znwm@plt>
movq   $0x400c78,(%rax)
mov    %rax,(%rbx)
mov    %rbx,%rax
pop    %rbx
retq
      

Quick guide - Bind templates

template<class TPolicy = class TErrorPolicy>
class simple_updater : TPolicy {
  void update() {
    TPolicy::on("update");
  }
};

template<class T = class TUpdater>
class example {
public:
  explicit example(const TUpdater& updater)
    : updater(updater)
  { }

  void update() {
    updater.update();
  }

private:
  const TUpdater& updater;
};

int main() {
  struct throw_policy {
    void on(std::string_view str) {
      throw std::runtime_error(str);
    }
  };
  const auto injector = di::make_injector(
    di::bind<class TErrorPolicy>.to<throw_policy>(),
    di::bind<class TUpdater>.to<simple_updater>()
  );

  injector.create<example>().update();
}

Clang-3.8 GCC-6 MSVC-2015
Compilation Time 0.102s 0.118s 0.296s
Binary size (stripped) 6.2kb 6.2kb 105kb
ASM x86-64

xor eax, eax
retq
      

Quick guide - Bind concepts

struct Streamable {
 template<class T>
 auto requires(T&& t) -> decltype(
   int( t.read() ),
   t.write(int)
 );
};

template<class Exchange = Streamable(class ExchangeStream)
         class Engine   = Streamable(class EngineStream)>
class example {
  example(Exchange exchange, Engine engine)
    : exchange(exchange), engine(engine)
  { }
};

int main() {
  const auto injector = di::make_injector(
    di::bind<Streamable(class ExchangeStream)>.to<exchange>(),
    di::bind<Streamable(class EngineStream)>.to<engine>()
  );

  injector.create<example>();
}

Clang-3.8 GCC-6 MSVC-2015
Compilation Time 0.102s 0.118s 0.296s
Binary size (stripped) 6.2kb 6.2kb 105kb
ASM x86-64

xor eax, eax
retq
      


Documentation


Disclaimer Boost.DI is not an official Boost library.