Do UML tools have some summary view that show a class object's attributes and methods, including those obtained from parent classes through inheritance?
For example, say I have diagrammed foobar's inheritance from foo (Python code):
class foo:
def doSomething(self):
print 'stuff'
class foobar(foo):
def dontJustStandThere(self):
self.doSomething()
The foobar diagram shows inheritance from foo, and method dontJustStandTherE(). The foo diagram shows method doSomething(). Now, instantiated foobar objects will have two methods -- dontJustStandThere(), and doSomething() (by inheritance). It would be nice to see a summary of foobar that just listed its methods and attributes, without breaking those down into their specific sources, and ideally ignoring parent class methods overloaded by subclasses. Such accumulation of methods into one object is one point of inheritance, yes?
Do UML tools have such a view, and what do they call it? I've looked around the guide and commands for the tool I'm using (Poseidon), and the web, and I don't seem to see anything like this -- but it seems so useful that I imagine it's there somehow.
(I suppose it's also possible that Poseidon is focused on Java code, and that differences in Java's specification for inheritance from Python's might be complicating things.)
In MagicDraw, when clicking on the properties on a class you see (in different boxes) at the same time the own properties of the object and inherited ones (and you can even change them, which updates the superclass owning the property)
Sparx Enterprise Architect does. You select the desired elements and choose the Feature Visibility command, and you can select whether inherited attributes and/or operations are visible:
UML 2.5 introduces a caret notation (e.g., ^ someAttribute: String) that allows you to show inherited members. Hopefully UML tools will support this notation soon.
Related
I am trying to create UML diagram. For example I have a class A with method a() and class B that extends A and overrides method a(). Is there any standard to indicate overridden methods in UML?
No, there is no specific indicator for operations that override operations on a parent class.
If the signature matches it overrides the operation on the parent.
The norms says on p. 101:
Inherited members may also be shown in a lighter color to help distinguish them from non-inherited members. A conforming implementation does not need to provide this option.
Sadly, my tool (EA) does not support that.
The simplest method is to duplicate only the operation signatures of those operations you are going to override. That will make it clear that you are overidding something.
By just looking to Class2 there is no way to tell that b is actually an override. However, if someone wants to deal with Class2 he must know that it's a subclass - and thus will know that b is an override.
Note: The UML 2.5 specs are ambigous about the caret use. While (on p. 100) they say
Members that are inherited by a Classifier may be shown on a diagram of that Classifier by prepending a caret ’^’ symbol ...
the syntax below explictely mentions only properties and connectors and this passage
Analogous notations may be used for all NamedElements that are inheritedMembers of a Classifier to indicate that they are inherited.
As indicated in that answer https://stackoverflow.com/a/28932482/2458991 there is a specific indicator to indicate a member (for instance an operation) is inherited, but that indicator is not mandatory, the norm says :
Members that are inherited by a Classifier may be shown on a diagram of that Classifier by prepending a caret ’^’ symbol to the textual representation that would be shown if the member were not inherited.
So, having :
B does not override oper
But having :
we cannot know except if we are sure the ^ is always used in the model as in previous diagram
[edit]
Notice the norm use two times the words member (and not properties) in that sentence, and Class inherits (indirectly) Classifier, so that applies for operations.
As noticed in an other answer the norm says also :
Inherited members may also be shown in a lighter color to help distinguish them from non-inherited **members*.
so again two times members rather than properties, and the fact they use also clearly reference the fact there is an other way which is the ^. So two consistent sentences indicating ^ applies to operations
[warning]
I used BoUML to make the diagrams and in the first you can see "^oper()" but I 'cheated' to do that naming the corresponding operation "^oper", there is no option to show a ^ in a diagram to indicate an operation or other member is inherited
I have class Controller in my java project, which has method like this:
As you can see, in the first line I am getting Singleton instance of ActualModes class and call method getActualModes().
So the first question is, which relatinship I should use in class diagram.
After that I am creating new instane of ModeContext class and then call method executeStrategy. In this case, which relatiship is better ?
It should be like this:
Access to the singleton (note the stereotype which is just convenient and no obligation or general standard) is anonymous and so you just have a dependency. The ModeContext in contrast uses a private (I don't know the scoping rules of the language you used, so I made it pivate) property called context. Note the dot which is saying exactly that.
Disclaimer: UML does not specify a mapping between Java and UML, so every answer to your question is open for debate.
I think both relationships are dependencies, drawn as dashed arrows from Controller to ActualModes and from Controller to ModeContext. The definition of 'dependency' according to the UML 2.5 specification (§7.8.4.1) is:
A Dependency is a Relationship that signifies that a single model Element or a set of model Elements requires other
model Elements for their specification or implementation.
An example of a type of relationship which is in my opinion less suited, is the association, although its definition (§11.5) is quite broad:
An Association classifies a set of tuples representing links between typed instances. (...) An Association specifies a semantic relationship that can occur between typed instances.
One could argue that there are links between Controller and the other two classes, in the form of variables, but these variables are local method variables, which exist only temporarily during the execution of the method. Associations represent more durable links, e.g. class members - as far as I understand UML and as far as I have seen associations used in practice.
Let's say I have class Foo that has an association to some thing(s) that fulfill(s) a role. This role could be fulfilled by either (strictly) one Bar xor any number of Baz. Similarly, the role might be fulfilled by either any number or Bar xor any number of Baz (but a mixed collection is intolerable). Are there reasonable ways to represent these in a class diagram using only associations, classes, and interfaces? I would (really) like to avoid using OCL or constraint elements.
(The reason I would like to avoid these is because we are generating code from our UML. We have already implemented generation that handles associations, classes, and interfaces. Dealing with OCL would be quite the task. Constraint elements wouldn't be so bad but still quite a lot of work.)
I would start with the picture below and create several different versions before deciding which one generates best code (junior-40).
The yellow blocks represent necessary "glue code" needed to straighten your example against your other requirements
Consider creating an abstract class Thing and derive Bar and Baz from it. It abstract the whole role, can contain some own atts and methods if needed and is quite flexible and extendible.
Now Account has an association only with AccountOwner (role "role", as Jim L. has explained in his comment, a role name must be unique in this context).
Note that this does not eliminate the need of some additional restrictions. For example, all linked "roles" should be of the same type. Sometimes is not easy (or even possible) to remove all restrictions. Otherwise we would make complete systems out of class diagram. I agree though, that as much information as possible should be contained in classes, their taxonomies and features (atts, assocs and methods).
EXAMPLE:
EXAMPLE 2 (after comments):
This version overcomes the need to use OCL ant yet keeps the simplicity and flexibility:
Multiplicities are now also derived and refined for each concrete "role". No OCL needed. :)
You add a constraint on the class in OCL:
(self.role->exists(r|r.oclIsType(Bar)) and self.role->notexists(r|r.oclIsType(Baz)) ) or
(self.role->exists(r|r.oclIsType(Baz)) and self.role->notexists(r|r.oclIsType(Bar)))
You can try this out with MDriven Designer.
The reason for introducing OCL (object constraint language) in the UML specification was just this; ability to add constraint not possible or practical to convey with simple cardinality and type information
Could this image help you ? It is extracted from the norm.
Are you thinking of something like the following:
(source: uml-diagrams.org)
Where Account is your Foo, Person is your Bar, and Corporation is your Baz.
You can then specify multiplicity on each of the two associations: [1] for Bar (Person) and [1..*] for Baz (Corporation).
hi every body i'm trying to understand UML but there are some questions about it
In UML what is the significance of tagging a class with the stereotype <<abstract>>?
and how to express this constraint as an invariant,
A stereotype "abstract" does not exist - an abstract class should be depicted using italic font. Abstract means that a class cannot be instantiated. It needs a subclass to do so. So as a pseudo-code constraint this would mean
for all instances i of MyAbstractClass holds: i.actualClass != MyAbstractClass
or in ocl for MyAbstractClass holds
self.allInstances()->forAll(i: MyAbstractClass | i.classifier <> self)
As the word 'abstract' was not displayed in your first question version, I expanded on stereotypes in general:
First of all: When learning UML, stereotypes should not be the first things you look into. They are rather complex.
Stereotypes or keywords (both denoted with <<MyStereotype>>) do not have a general meaning. It is defined by the specific stereotype. Commonly you cannot express a stereotype as an invariant instead.
But some other aspects of UML can be shown the same way: A class from the UML Metalevel is marked with <<metaclass>> even though it does not have a stereotype or even is of different actual type. The Stereotypes themselves are shown with a <<stereotype>> marker (even if they are instances of a special class).
An example for a custom stereotype could be "Service". You could mark classes with it which represent a Service. There could be a constraint which tells you that a "Service" must implement a special Interface. In this case you could express this constraint as a (boring) invariant. But probably it is even just a marker. In the latter case you can use a keyword as replacement.
I realize this thread is a couple of years old, but I came to it when it was referenced by someone else, as supporting the assertion that the «abstract» stereotype isn't supported by the UML spec. That assertion isn't quite accurate, and I'd like to explain why. I'll start by clarifying what abstract classes are.
Abstract classes are definitions of classes that don't include complete implementation. Therefore, abstract classes can't be directly instantiated; they have to be specialized (inherited). Abstract classes are notated by italicizing the class name and the methods that are abstract, and additionally by optionally adding an {abstract} property to the class name and/or to the operations (methods, we usually say, but methods are actually the "method" by which the operation is implemented) that are abstract.
Interfaces are actually a specific type of abstract class: a class with zero implementation. Their notation is different from other types of abstract classes (don't italicize, use the «interface» keyword, and notate all the specialization arrows with dotted lines). So, as Christian says here, there is standard notation for abstract classes--at least, there is in class diagrams.
Now, while it is true, as Christian also says, that the «abstract» stereotype doesn't exist, it is also true that you can create it if you want to, and that doing so is supported by the UML spec. It's unlikely that you'll have a reason to (at least in class diagrams), but you still can.
A stereotype is an "extensibility mechanism" for UML (there are three: stereotypes, tagged values, and constraints). It allows you to more specifically define some sort of element. Stereotypes are applied to classes (metaclasses actually, metaclasses are classes whose instances are also classes). A number of stereotypes are pre-defined "Standard Stereotypes" (in UML 1.4 they were called "Standard Elements"). Examples of these are «metaclass» (again, a class whose instances are also classes) and «file» (a physical file in the context of the system developed).
Stereotypes are a type of keyword. The spec (Superstructure 2.0, Annex B, p. 663) has this to say about keywords:
UML keywords are reserved words that are an integral part of the UML
notation and normally appear as text annotations attached to a UML
graphic element or as part of a text line in a UML diagram. These
words...cannot be used to name user-defined model elements where such naming would result in ambiguous interpretation of
the model. For example, the keyword “trace” is a system-defined
stereotype of Abstraction (see Annex C, “Standard Stereotypes”) and,
therefore, cannot be used to define any user-defined stereotype.
In UML, keywords are used for four different purposes:
To distinguish a particular UML concept (metaclass) from others sharing the same general graphical form...
To distinguish a particular kind of relationship between UML concepts (meta-association) from other relationships sharing the same general graphical form...
To specify the value of some modifier attached to a UML concept (meta-attribute value)...
To indicate a Standard Stereotype (see Annex C, “Standard Stereotypes”)...
Keywords are always enclosed in guillemets («keyword»), which serve as visual cues to more readily distinguish when a keyword is being used...In addition to identifying keywords, guillemets are also used to distinguish the usage of stereotypes defined in user profiles. This means that:
Not all words appearing between guillemets are necessarily keywords (i.e., reserved words), and
words appearing in guillemets do not necessarily represent stereotypes.
In other words, you can create any stereotype that you want, so long as it isn't a keyword. Since "abstract" is not a keyword, it follows that you can create an «abstract» stereotype.
In order to do so, however, you would have to go to some trouble, more trouble in UML 2.0 and above than in UML 1.4. UML 1.4 simply stated that a stereotype was an extension mechanism for the UML spec. One could simply define the stereotype, apply it to whichever part of the UML metamodel one wanted, and document the change. UML 2.0 wanted to formalize the relationship of a stereotype to a UML metaclass (any item on a UML diagram is a metaclass, and part of the UML metamodel). So, they came up with Profiles. This sample diagram shows how profiles work:
Now, that black arrow may look a bit strange, since you don't see it in any context but this one. UML 2.0 introduced the concept of an Extension, which it defines as "used to indicate that the properties of a metaclass are extended through a stereotype." This black arrow indicates an extension.
I'll quote Tom Pender (The UML Bible, Wiley Publishing, 2004) for an explanation of this diagram, since he does a better job than the spec (and I certainly can't improve on it):
It shows that a Component is extended by a Bean stereotype, which is required. The Bean stereotype is an abstract type, with two subtypes - Entity and Session. Each instance of Component, therefore, must be extended by an instance of either the Entity stereotype or the Session stereotype. Remember that a stereotype is a kind of class that can have properties - in this case, a Session stereotype has an attribute named state. This corresponds to a tagged definition whose value specifies the state of the Session. The tagged value is an enumeration, StateKind, which has either a stateless or stateful value.
The Component has a constraint on it, displayed in the note attached to the Component symbol, which states that a Component cannot be generalized or
specialized.
The diagram also shows that an Interface metaclass is extended by the Remote and Home stereotypes. The EJB package has a constraint, displayed in the note that sits in the package, that states a Bean must realize exactly one Home interface.
So, you can indeed use an «abstract» stereotype if you have reason to go to the trouble of creating it. The main reason that anyone might want to is to represent an abstract class in some place other than a class diagram.
In a UML diagram when you create an instance of a subclass do you usually include the implicit construction of the superclass prior to the sub class constructor?
I usually wouldn't include it. The purpose of the UML sequence diagram is to show what happens between components. It shouldn't be read isolated from other parts of a design, so if a reader is unsure about what any of the components is (i.e. an instance of the subclass and the superclass), he or she should look into the - hopefully - accompanying class diagram.
sequence just shows the sequence of the logic of the module in question. Do you feel there is need to identify which method is truly being called? Also I would guess that the purpose of having a parent clas have a reference to a subclass is that until runtime you won't know which subclass is actually being referred to. If this is not the case, then should the concrete subclass be referred to explictly? does the method being called whether on the subclass or parent class alter the sequence in some way?