The JessTab command make-instance creates a new instance of a class. I do not want to create a new instance, but instead use an existing one and set it to be also an instance of another class. Is it feasible to do it with JessTab commands?
A make-instance like this
(make-instance paul of Person (name "Paul") (age 42))
creates a shadow fact, which has a single OBJECT slot referencing the object, and a slot defining the class, e.g., (is-a Person). Apart from any object naturally being also an object of its superclass as well, an object cannot be made to be an instance of another class.
Maybe you are trying to solve a problem that can be better addressed using another approach - why don't you ask about that in the first place?
Related
Backround to the problem: I have connected two classes to each other in UML, both of them being regular classes and one of them is named "League".
In the "miscellaneous" menu in MDriven, I found that the following “EffectiveName": "League_children” as well as "OtherEnd": "League_parent".
This was confusing in three ways:
There is not a class named "League" in "OtherEnd"
The terms "League_children” and "League_parent" were created automatically
It says "League_children" not "LeagueChildren" with the latter one I thought was more correct becuase of how you write in code, and also everywere else in the diagrams and menus in MDriven's workspace.
I read about the terms "children" and "parent" in the official book (https://www.capableobjects.com/xdownloads/MDrivenTheBook/MDrivenTheBook-Part2-Design.pdf ) and obviously these are used when you have superclasses and subclasses to those. However, neither "League" or any other class in my diagrams as of now are superclasses", so why are these names created then?
Furthermore, "OtherEnd" is not called "League" and therefore shouldn't have be called "League_parent".
I searched through my different classes and found no hidden associations that I had acidentally/falsely deleted.
I recognize the _Parent _Children pattern as what MDriven does when adding an association from a class back to the same class.
If you check the Class in the tree I bet you will find an association pointing back to self. If this was added by mistake - delete it.
Normally MDriven leaves the name of association ends blank - then the effective name will be the name of the Class in the end. Name - if set - overrides this.
When creating associations back to self - MDriven sets the names of the ends appending _Parent and _Children.
I know that there are ways to access an EAttribute of an Eclipse EMF model by its featureID or by its name via different indirect approaches. For that I found the following: Eclipse EMF: How to get access EAttribute by name?
But what if I don't know the name of the attribute I want to get? Let's say, based on the design, the model has some fixed attributes by the developer, along with the features that can be set dynamically by the user.
So, for the time being I use the getEAllStructuralFeatures() and use indexes via get() to reach to the by-the-user-created attributes, since I know that the list I get will have the fixed attributes of the model as its first elements beginning with the index 0. But I find this solution unclear and inefficient. Also in some cases, that I want to work, not suitable.
E.g: IEMFEditProperty prop = EMFEditProperties.list(editingDomain, EMFMODELPackage.Literals.EMFMODEL.getEAllStructuralFeatures().get(X));
Do you know a solution or a workaround for this problem? As far as I can see, there are no direct methods to get such dynamically created features of the model.
Every help will be appreciated.
I have been working on a similar case recently where I first tried to define an EStructuralFeature to access exactly the setting/attribute of the object that I needed.
But if you look at how things work internally in ECore, you will find out, that there is no way this will ever work, since the indices are bound to the object identity of the EStructuralFeature objects created at runtime for the specific context (i.e. EClass instance).
My approach was then to either inspect the features proposed by EClass.getEAllStructuralFeatures or to iterate over the features and inspect the object returned by EObject.eGet for this very feature (where EClass eClass = eObject.eClass()).
Example: In a UML profile I have defined a UML Stereotype called "Bean" with a property called FactoryEntity. The property shall reference a UML Class with the Stereotype "Entity" that is closest to this very bean and for which a static factory method will be generated.
In the model I would then have one UML Class typed as Bean and one as Entity.
And for the Class typed as "Bean" I would then set a value for the attribute/property factoryEntity defined in the profile.
The question was then how the property value would be accessible in ECore. I ended up iterating the List of available EStructuralFeature of the EClass of the EObject and checking the type of the object returned by eGet.
final EObject eObject = (EObject) holdingClass.getValue(stereotype, stereoTypePropertyName);
final EList<EStructuralFeature> allEStructFeats = eObject.eClass().getEAllStructuralFeatures();
for(EStructuralFeature esf : allEStructFeats)
{
final Object o = eobject.eGet(esf);
if(o instanceof org.eclipse.uml2.uml.Class)
{
return (org.eclipse.uml2.uml.Class) o;
}
}
Maybe that is not the most elegant way to access structural features but it is the only one I thought was robust enough to last.
Please let me know if you have any suggestions on how to improve this.
Is there a bulit-in way to obtain an entity name from the class object of an NSManagedObjectSubclass? I know that this can be readily determined from an instance of a subclass, but I want to ask the class itself. I can write a class function, but I would rather do this introspectively.
You can do it now by executing NSManagedObject.entity().name where NSManagedObject() is your subclass.
Check out mogenerator if you haven't already.
http://raptureinvenice.com/getting-started-with-mogenerator/
It adds a lot of missing features to core data. In particular it keeps you from having to regenerate your entity classes.
You could iterate thru the key values of the entities in the context:
[managedObjectContext registeredObjects];
What is the difference between the System.ComponentModel.BindingList methods Add(object) and AddNew()? The MSDN documentation says this:
Add: Adds an object to the end of the Collection<T>.
AddNew: Adds a new item to the collection.
It seems like both methods add an item to the collection, but Add(object) does it in one shot whereas AddNew() is slightly more complicated. My tests with Add(object) seem to be working, but I want to know if I am using the correct method.
So what is the difference between these methods?
AddNew() creates the object for you (that's why it doesn't have a parameter).
It's designed to be used by grids, which don't know how to create a new object to pass to Add().
AddNew() is very handy (it’s the well-known Factory design pattern) when you implement a class derived of BindingList().
It allows your code to initialize new items with values that depend on the list itself - e.g. a foreign key to the parent object if the binding list contains a list of children.
I have already created an interface, and I am in the class that binds to the interface.
If I create a new method in the concret class, is there a shortcut to create the method declaration in the interface?
Refactor - Pull Members Up:
This refactoring helps you move type members to a superclass or an interface. This operation is useful as a way to generalize behavior. ReSharper analyzes all members in the current class and makes a list of members that you can pull up. Before completing the refactoring, ReSharper also checks for possible conflicts, for example, whether the members that you are trying to move to a superclass will be accessible in the destination type. The reverse functionality is available with 'Push Members Down'.
The keyboard shortcut for invoking this re-factoring is: Alt+R > R > U