c++ virtual class, subclass and selfreference - c++

consider this class:
class baseController {
/* Action handler array*/
std::unordered_map<unsigned int, baseController*> actionControllers;
protected:
/**
* Initialization. Can be optionally implemented.
*/
virtual void init() {
}
/**
* This must be implemented by subclasses in order to implement their action
* management
*/
virtual void handleAction(ACTION action, baseController *source) = 0;
/**
* Adds an action controller for an action. The actions specified in the
* action array won't be passed to handleAction. If a controller is already
* present for a certain action, it will be replaced.
*/
void attachActionController(unsigned int *actionArr, int len,
baseController *controller);
/**
*
* checks if any controller is attached to an action
*
*/
bool checkIfActionIsHandled(unsigned int action);
/**
*
* removes actions from the action-controller filter.
* returns false if the action was not in the filter.
* Controllers are not destoyed.
*/
bool removeActionFromHandler(unsigned int action);
public:
baseController();
void doAction(ACTION action, baseController *source);
};
}
and this subclass
class testController : public baseController{
testController tc;
protected:
void init(){
cout << "init of test";
}
void handleAction(ACTION action, baseController *source){
cout << "nothing\n";
}
};
The compiler comes out with an error on the subclass on the member
testController tc;
..saying
error: field ‘tc’ has incomplete type
but if I remove that and I instatiate the class it works... is there a way to avoid this error??? It looks so strange to me....

one day someone asked me why a class can't contain an instance of itself and i said;
one day someone asked me why a class can't contain an instance of itself and i said;
one day someone asked me why a class can't contain an instance of itself and i said;
...
use indirection. a (smart) pointer or refrence to a testController rather than a testController.

Your code is trying to embed an entire instance of testController inside itself, which is impossible. Instead, you want a reference:
testController &tc;
or a pointer
testController *tc;

It won't compile because you're declaring a member variable 'tc' that is an instance of itself. You're not using tc in the subclass; what is your intent here?

You can not create an object of the class inside that class itself. Probably what you intend to do is to keep a pointer to the class. In that case you should use it as testController* BTW, why do you want to do that? It looks a bit strange to me.

(A bit late to the party, but ...)
Maybe gotch4 meant to type something like this?
class testController : public baseController
{
public:
testController tc(); // <- () makes this a c'tor, not a member variable
// ( ... snip ... )
};

Related

Mock class object as parameter of function

I am using junit and mokito to write unit test of my java program.
public MyClass {
private ClassA a;
public void process(ClassB b) {
if(b.method()) a = ClassA.builder().build();
}
}
Now I have write a MockClassA and MockClassB. But I don't know how to :
Pass a MockClassB instantiation to process function
How to verify whether private variable a is set successfully
Can anybody help?
You can use something like:
#Test
public void shouldDoSomething() {
// given
ClassB mock = Mockito.mock(ClassB.class);
Mockito.when(mock.method()).thenReturn(true);
MyClass classUnderTest = new MyClass();
// when
classUnderTest.process(mock);
// then
// Insert assertions
}
However, if your field is private you are unable to test it properly. You should provide a getter for this field if you want to make some assertions against it.
But remember that internal representation of MyClass should not be tested, only the behavior of it so maybe you want to try different approach

Builder pattern - configuration file reading

I'm facing a design problem. I want to separate building objects with a builder pattern, but the problem is that objects have to be built from configuration file.
So far I have decided that all objects, created from configuration, will be stored in DataContext class (container for all objects), because these objects states will be updated from a transmission (so it's easier to have them in one place).
I'm using external library for reading from XML file - and my question is how to hide it - is it better to inject it to concreteBuilder class? I have to notice that builder class will have to create lots of objects and at the end - connect them between each other.
Base class could look like that:
/*
* IDataContextBuilder
* base class for building data context object
* and sub obejcts
*/
class IDataContextBuilder {
public:
/*
* GetResult()
* returns result of building process
*/
virtual DataContext * GetResult () = 0;
/*
* Virtual destructor
*/
virtual ~IDataContextBuilder() { }
};
class ConcreteDataContextBuilder {
public:
ConcreteDataContextBuilder(pugi::xml_node & rootNode);
DataContext * GetResult ();
}
How to implement it correctly? What could be better pattern to build classes from configuration files?
I don't see a problem with that, but maybe you could inject another 'Director' class that receives a specific builder, loads the config files, and produces objects calling the respective builder-subclasses.
What I mean:
class DataContextDirector {
public:
void SetBuilder(IDataContextBuilder* builder);
void SetConfig(const std::string& configFilePath); // or whatever
DataContext* ProduceObject() {
// pseudo-code here:
// myBuilder->setup(xmlNodeOfConfig);
// return myBuilder->GetResult();
}
};

should we create object of any class on class level or function level

Which approach is better: I tried to find it on web, but I couldn't get a better answer.
1.
public class OtherClass
{
public int Add(int x, int y)
{
return x + y;
}
}
public class TestClass
{
OtherClass oClass = new OtherClass();
public int Fun1()
{
return oClass.Add(1,2);
}
public int Fun2()
{
return oClass.Add(1, 2);
}
}
2.
public class TestClass
{
public int Fun1()
{
OtherClass oClass = new OtherClass();
return oClass.Add(1, 2);
}
public int Fun2()
{
OtherClass oClass = new OtherClass();
return oClass.Add(1, 2);
}
}
I think it depends on what you are trying to test.
If you're testing the effects of a sequence of functions being executed on the same class instance then you might want to create a single instance (such as stress testing)
But otherwise I'd say it's always better to create a new instance of the class in each test function to ensure that the context of each test is predictable. If your test methods shared an instance of a class, and one test method fails and corrupts the state of the object under test, your subsequent test may fail for no other reason than the state of the object under test was corrupted by the previous failed test (it might appear the multiple tests are failing when in fact only one of the early ones is a true failure).
Depends on the scenario, if the class is gonna be shared on multiple functions and there are no specific arguments needed to create an instance of that class then it's better of being at the class level.
Let's say you're using the Fun1 and Fun2 often, having the instance creation on the method will have instance creation overhead rather than it being at the class level having a single instance, or better yet, make it static or make it singleton if you're sure that it's going to be a single instance throughout the whole app.
One benefit of having it in the class level is if you're doing unit testing, you can make an interface like IOtherClass and Inject it in the constructor of TestClass.
It would look something like this.
public class OtherClass : IOtherClass
{
public int Add(int x, int y)
{
return x + y;
}
}
public class TestClass
{
IOtherClass oClass;
public TestClass(IOtherClass _oClass)
{
oClass = _oClass;
}
public int Fun1()
{
return oClass.Add(1,2);
}
public int Fun2()
{
return oClass.Add(1, 2);
}
}
You're better off having it as a field in the class rather than declaring a new one in each method. The reason for this is simple, there won't be a line of code in each method declaring the variable meaning that if your declaration statement changes you will only have to change it in one place, not every method. Also it will make your code easier to read and add to because this line won't be duplicated everywhere.
Just remember if that field needs to be disposed your class should implement the IDisposable interface.

Partial Mock or new class or what else?

I have a question about testing.
I have a class that returns anomalies. in this class I have two different method that simply returns two different types of anomalies and one that return all anomalies (of both types)
this is the example code:
public interface IAnomalyService
{
IList<Anomaly> GetAllAnomalies(object parameter1, object parameter2);
IList<Anomaly> GetAnomalies_OfTypeA(object parameter1);
IList<Anomaly> GetAnomalies_OfTypeB(object parameter2);
}
public class AnomalyService : IAnomalyService
{
public IList<Anomaly> GetAllAnomalies(object parameter1, object parameter2)
{
var lstAll = new List<Anomaly>();
lstAll.AddRange(GetAnomalies_OfTypeA(parameter1));
lstAll.AddRange(GetAnomalies_OfTypeB(parameter2));
return lstAll;
}
public IList<Anomaly> GetAnomalies_OfTypeA(object parameter1)
{
//some elaborations
return new List<Anomaly> { new Anomaly { Id = 1 } };
}
public IList<Anomaly> GetAnomalies_OfTypeB(object parameter2)
{
//some elaborations
return new List<Anomaly> { new Anomaly { Id = 2 } };
}
}
class Anomaly
{
public int Id { get; set; }
}
I've created the tests for the two method that retrieve the anomalies of type A and type B (GetAnomalies_OfTypeA and GetAnomalies_OfTypeB).
Now I want to test the function GetAllAnomalies but I'm not sure what I have to do.
I think I have to way for testing it:
1) declare GetAnomalies_OfTypeA and GetAnomalies_OfTypeB in class AnomalyService as virtual, make a mock of the Class AnomalyService, and using Moq I can set CallBase as true and mock the two method GetAnomalies_OfTypeA and GetAnomalies_OfTypeB.
2)move the method GetAllAnomalies in another class called AllAnomalyService (with interface IAllAnomalyService) and in its constructor I will pass an interface of IAnomalyService and after I can test the GetAllAnomalies mocking the IAnomalyService interface.
I'm new at unit testing, so I don't know which solution is better, if is one of the mines or another one.
Can you help me?
thank you
Luca
Mocking is a good tool when a class resists testing. If you have the source, mocking is often not necessary. Try this approach:
Create a factory which can return AnomalyServices with various, defined anomalies (only type A, only type B, both, none, only type C, ...)
Since the three types are connected in some way, you should check all three in each test. If only anomalies of type A are expected, you should check that GetAllAnomalies returns the same result as GetAnomalies_OfTypeA and GetAnomalies_OfTypeB returns an empty list.

Doctrine2 __constructor not called when using $em->find(); ? How to load entity properly?

I'm learning doctrine2, and having a problem how to call constructor automatically.
For example, in my entity I have
/**
* #Entity
*/
class User{
....
public function __construct() {
exit('in');
}
}
and when I get the object this way:
$userObj = $em->find('User', 1);
I do get that object from database, but constructor is never called.
I want to put some common things in constructor, like validation rules, or even to put sample code from the doctrine documentation like
$this->comments = new ArrayCollection();
This ofcourse works when I create new object in code for creating a user like
$user = new User(); //now constructor works just fine
Now, what is the "proper" way of getting the entity? I doubt I have to call constructor manually each time I user $em->find() with $user0bj->__construct(); ? This would kinda sucks then... Or I should use something other then ->find() to get single entity properly?
I know I can user #PrePersist, and I am using it to actually do validation checks etc.
I guess that I'm probably missing something here, or I'm trying to use constructor in a poor way. Thanks for any explanations and guides!
I'm pretty certain that find or similar isn't expected to call the constructor...
You need to hook into the #PostLoad event.
Why would you want to call the constuctor of already persisted entity? When you need to validate it you should have done the validation or initializations before you have persisted it. So When you call a already persisted entity there is no point to validate it.
The right place to put validation and other initializations is the constructor method of entity.
Eg.
/**
* #Entity
*/
class User{
protected $name;
public function __construct($name) {
if (isset($name)) {
//** validate the name here */
$this->name=$name;
} else {
throw new Exception("no user name set!");
}
}
}
According to the doctrine2 documentation Doctrine2 never calls __construct() method of entities.
http://www.doctrine-project.org/docs/orm/2.0/en/reference/architecture.html?highlight=construct
doctrine uses reflection to instantiate your object without invoking your constructor.
Since PHP 5.4 , you can use reflection to instanciate a class without
calling the constructor using
ReflectionClass::newInstanceWithoutConstructor
the instantiator of doctrine use it like :
private function buildFactory(string $className) : callable
{
$reflectionClass = $this->getReflectionClass($className);
if ($this->isInstantiableViaReflection($reflectionClass)) {
return [$reflectionClass, 'newInstanceWithoutConstructor'];
}
$serializedString = sprintf(
'%s:%d:"%s":0:{}',
is_subclass_of($className, Serializable::class) ? self::SERIALIZATION_FORMAT_USE_UNSERIALIZER : self::SERIALIZATION_FORMAT_AVOID_UNSERIALIZER,
strlen($className),
$className
);
$this->checkIfUnSerializationIsSupported($reflectionClass, $serializedString);
return static function () use ($serializedString) {
return unserialize($serializedString);
};
}
Doctrine ORM will "rewrite" your class, it generate a new class that implement \Doctrine\ORM\Proxy\Proxy
And it rewrite the construct method:
/**
* #param \Closure $initializer
* #param \Closure $cloner
*/
public function __construct($initializer = null, $cloner = null)
{
$this->__initializer__ = $initializer;
$this->__cloner__ = $cloner;
}
You can see it inside the cache folder ${CACHE}/doctrine/orm/Proxies.
You will need both #ORM\HasLifecycleCallbacks on the class + #ORM\PostLoad on a specific function of your choice.
Beware! If you put it on the constructor it will override loaded database data!
use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\ORM\Mapping as ORM;
/**
* #ORM\Table(name="dossier")
* #ORM\Entity()
* #ORM\HasLifecycleCallbacks
*/
class Dossier
{
// ...
/**
* The normal constructor stays as usual
*/
public function __construct()
{
$this->takenActions = new ArrayCollection();
$this->classifications = new ArrayCollection();
$this->dossierProblems = new ArrayCollection();
$this->internalNotes = new ArrayCollection();
}
/**
* Triggers after the entity has been loaded in the EntityManager (e.g. Doctrine's ->find() etc...)
* The constructor does not get called. Some variables still need a default value
* Must be in combination with "ORM\HasLifecycleCallbacks" on the class
*
* #ORM\PostLoad
*/
public function postLoadCallback(): void
{
// Only put a default value when it has none yet
if (!$this->dossierProblems)
$this->dossierProblems = new ArrayCollection();
if (!$this->internalNotes)
$this->internalNotes = new ArrayCollection();
}
// ...
}