Nuria::DependencyManager Class Reference

Dependency injection manager. More...

#include <dependencymanager.hpp>

Inheritance diagram for Nuria::DependencyManager:

Public Types
enum	ThreadingPolicy { DefaultPolicy, ApplicationGlobal, SingleThread, ThreadLocal }

Public Member Functions
	~DependencyManager ()
ThreadingPolicy	defaultThreadingPolicy () const
bool	hasObject (const QByteArray &name, ThreadingPolicy policy=DefaultPolicy) const
void *	objectByName (const QByteArray &name, int type=-1, ThreadingPolicy policy=DefaultPolicy)
int	objectType (const QByteArray &name, ThreadingPolicy policy=DefaultPolicy) const
void	setCreator (const QByteArray &name, const std::function< QObject *() > &creator)
void	setDefaultThreadingPolicy (ThreadingPolicy policy)
void	storeObject (const QByteArray &name, void *object, int type, ThreadingPolicy policy=DefaultPolicy)
template<typename T >
void	storeObject (const QByteArray &name, T *object)

Static Public Member Functions
template<typename T >
static T *	get (const QByteArray &name, ThreadingPolicy policy=DefaultPolicy)
static DependencyManager *	instance ()

Detailed Description

Dependency injection manager.

Dependency injection is interesting whenever a class has dependencies to other utility classes. Those classes usually only have a single application-wide instance, thus those are often implemented as singletons. While using singletons is mostly easy to do, it has also its flaws:

1. It requires additional methods to be implemented. Granted this is easy, but it's also really repetitive.
2. It's really hard to test classes which rely on singletons.

Usage

First, you'll need to register all classes which you want to use as dependencies to the Qt meta system:

Q_DECLARE_METATYPE(MyType*)

This line should come right after the class definition. Please note that the macro itself must be invoked on the global scope.

Note

'MyType' must inherit QObject.

After this, you can start using it right away with the NURIA_DEPENDENCY macro:

MyType *myType = NURIA_DEPENDENCY(MyType)

Requirements for dependency classes

If DependencyManager should create instances on-demand, a constructor which takes zero (Or only optional ones) arguments must be annotated using Q_INVOKABLE.

Using creators

If the name of the object doesn't match the typename, or if you need to do further initialisation work alongside the constructor, you can set a 'creator' using setCreator().

Note

This is especially helpful in multi-threaded applications!

Usage in unit-tests

For more fine-grained control, please see the methods this class offers. If you're writing unit tests, then you're probably interested in storeObject(). Example:

Nuria::DependencyManager::instance ()->storeObject ("MyType", myType);

Note

You have to supply a name here as the code won't be able to figure out the name itself.

Member Enumeration Documentation

enum Nuria::DependencyManager::ThreadingPolicy

Behaviours for multi-threaded applications.

See also

defaultBehaviour

Enumerator
DefaultPolicy	Maps to the current default policy.
ApplicationGlobal	One pool for all objects, but with a mutex guarding the internal structures.
SingleThread	One pool for all objects, with no mutex guards. Use this setting for single-threaded applications.
ThreadLocal	One pool per thread. Objects are freed when the thread gets destroyed, though some structures can only be freed upon application exit. Note This is the default behaviour

Constructor & Destructor Documentation

Nuria::DependencyManager::~DependencyManager

(

)

Destructor.

Member Function Documentation

ThreadingPolicy Nuria::DependencyManager::defaultThreadingPolicy

(

)

const

Returns the current default threading policy.

See also

setDefaultThreadingPolicy ThreadingPolicy

template<typename T >

static T* Nuria::DependencyManager::get ( const QByteArray &  name, ThreadingPolicy  policy = DefaultPolicy  )

inlinestatic

Tries to find object name of type T. On failure, nullptr is returned.

bool Nuria::DependencyManager::hasObject ( const QByteArray &  name, ThreadingPolicy  policy = DefaultPolicy  ) const

inline

Returns true if there is object name.

static DependencyManager* Nuria::DependencyManager::instance ( )

static

Returns the global instance of the manager.

void* Nuria::DependencyManager::objectByName	(	const QByteArray &	name,
		int	type = -1,
		ThreadingPolicy	policy = DefaultPolicy
	)

Returns object name. If type is not -1 and name wasn't created yet, it will be created then, stored and returned. Else, nullptr is returned.

Note

If type is not -1, it will be used as type check. If type and the type of object name don't match, nullptr is returned.

See also

getDependency NURIA_DEPENDENCY objectType

int Nuria::DependencyManager::objectType	(	const QByteArray &	name,
		ThreadingPolicy	policy = DefaultPolicy
	)		const

Returns the meta type of object name or -1 if not found.

void Nuria::DependencyManager::setCreator	(	const QByteArray &	name,
		const std::function< QObject *() > &	creator
	)

Sets the creator of object name to creator. When the object name is read and has not been created yet, creator will be called.

Please note that this function is not thread-safe, as you'll use this function at the start of your application and then start threads.

Note

creator must be thread-safe!

void Nuria::DependencyManager::setDefaultThreadingPolicy

(

ThreadingPolicy

policy

)

Sets the default threading policy. Passing DefaultPolicy has no effect. Changing the policy is not thread-safe.

See also

ThreadingPolicy

void Nuria::DependencyManager::storeObject	(	const QByteArray &	name,
		void *	object,
		int	type,
		ThreadingPolicy	policy = DefaultPolicy
	)

Stores object of type as name. If there is already a object of the same name, it will be overwritten. object must be a registered type.

See also

Q_DECLARE_METATYPE qRegisterMetaType

template<typename T >

void Nuria::DependencyManager::storeObject ( const QByteArray &  name, T *  object  )

inline

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

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The documentation for this class was generated from the following file:

• dependencymanager.hpp