How is a class diagram converted into code? - class

I was self-studying various UML diagrams and I understood most of them except for Class Diagram and Object Diagram.
I can not get my head around how they wil be converted into code.
The trick that I learnt is this: all nouns become classes and verbs become methods of the classes.
All good till there but after that, how is the diagram converted into code?
Have a look at a diagram here that I got from the internet:
So, assuming that the language is Java, how will you code a software based on this?

A UML diagram solely describes the internal architecture of a given piece of software.
The information contained in your UML diagram is therefore:
What classes are contained
What methods and properties do they contain
How do they relate to each other
Each block with a header ("Train" for instance ) represents a class, listing its properties and methods.
As such the UML diagram does not state anything about a GUI or how the user interacts with the software. It is up to you or a UI/UX designer to create an interface you can implement, that uses the functionality outlined in this UML diagram.
You can think of a UML diagram as a description of the architecture of a piece of software, that is very shallow but is well suited for an overview of the project.
It is not a recipe.
I hope this was useful to you.

When you have a class diagram, you have a representation of the classes (and its members) that you should have in code.
So, your noun/verb analysis (what you were talking about), has already been done when you have a class diagram.
A class diagram is just a visual representation of your classes, converting them to code is just easy if you know the syntax of the language that you want to use.

Related

How to read this UML diagram?

I work in the aviation industry, and I am trying to understand this UML diagram. I did a little bit of UML in college. Can you help me to interpret this diagram?
What is the difference between << extend >> and << select >>?
What do the big black arrows mean?
I didn't understand how to read the graph.
«extend»and «select» are stereotypes which were given a certain meaning in the domain of that model. Usually a profile is used to define the sterotypes and their meaning. So the best is you contact the author of the diagram and ask about it. There is no general answer. It looks a bit like these are meant to be requirements.
The "black arrows" with the lozenge are associations that are given a composite aggregation attribute. The lozenge-side is responsible for the lifetime of the other side. Means it will destroy them when it is destroyed itself.
Fun note about the «class» (as per comment from Axel Scheithauer from p. 99 of UML 2.5:
If the default notation is used for a Classifier, a keyword corresponding to the metaclass of the Classifier shall be shown in guillemets above the name. The keywords for each metaclass are listed in Annex C and are specified in the notation for each subclass of Classifier. No keyword is needed to indicate that the metaclass is Class.
So putting that keyword there is like painting "car" on a car to make it a car, obviously.

Creating an overall class diagram with Doxygen

I am trying to generate a Doxygen documentation for my Python project.
It seems like Doxygen does not provide an overall class diagram of the project including Association. It shows only inheritance for a single file.
Is there is a way I can generate an overall class diagram in doxygen?
Thanks a lot!
Doxygen does not generate class diagrams that contain "association" arrows.
These are the diagram types and my experience with them (stemming from C++):
CLASS_DIAGRAMS: Seems to be an old Doxygen option, superseded by CLASS_GRAPH, which contains more information. CLASS_DIAGRAMS often just show the class without anything else in my output, which is superfluous.
CLASS_GRAPH: This is actually an inheritance diagram, not a full class diagram (internally, it even goes by the name "inherit graph"). It doesn't show a diagram at all if a class is not a derived class or base class.
COLLABORATION_GRAPH: Shows base class, membership and template relations. Doesn't show "inherited by" or "used by" relationships. For a leaf class, the inheritance diagram (CLASS_GRAPH) is just a part of the COLLABORATION_GRAPH.
TEMPLATE_RELATIONS: Shows template relations in a similar style as inheritance, which is helpful for code using template specialization instead of inheritance, e.g. CRTP.
As you have a python project, did you try out Sphinx? sphinx.ext.inheritance_diagram comes included with the sphinx-doc distribution but also does not show other types of relations than inheritance.
A web search turned out https://pypi.org/project/sphinx-pyreverse/ which might be what you're looking for. I did not try it out myself.

Showing classes in dependent ontologies when creating class hierarchy with OWL API

I want to create a class hierarchy of the classes in an ontology using OWL API, similar to what you might see if you loaded an ontology in a tool such as Protege.
An example of how to do this may be found here: http://sourceforge.net/p/owlapi/mailman/message/27600103/.
As you can see, it seems difficult to reproduce the Protege hierarchy precisely using OWL API, and I am wondering if there is an example which will reproduce Protege's behaviour or if the fundamental reasons for not being able to do so may be clarified so an alternative approach may be found. I have had similar problems to the author of the post above, in that I can't seem to consistently reproduce the hierarchy shown by Protege by recursively going through the classes and subclasses, starting at owl:Thing, in order to create the full class hierarchy.
I need to:
Create not only the class hierarchy structure of the top level ontology being parsed, but also show the hierarchical relationships with classes in dependent ontologies, as Protege does. Protege shows the classes in the top level ('active') ontology in bold, with classes taken from dependent ontologies in normal print.
Create the hierarchy consistent with that shown by Protege for the same active ontology. I am assuming the hierarchy shown by Protege is correct?
I am happy to post code snippets and examples if desired, please do ask.
The Protégé hierarchy is not a plain hierarchy - Protégé does some reasoning to enrich it, at the behest of its users.
If you have code snippets you wish to refine, it would be useful to see the code, an ontology snippet and what you wish the result to look like - for example, a Protégé screenshot. Then it will be easier to refine the answer.

Enterprise Architect - How to create classes from sequence diagrams?

I have experience with StarUML and Jumli. At my current company we have a Professional license for EA 9.2.
When I design a program, I start with creating Use Cases. Then from every Use Case, I create a Sequence Diagram. And from the Sequence Diagrams, almost every Lifeline-object will become a class (and all messages will become a method). With StarUML and Jumli this wasn't a problem.
But I cannot find a way in EA to convert the Lifeline objects into classes.
I tried to read the help from Sparx, but to me it is not really helpful. Their 'tutorial' is not a tutorial, but actually just another help file with lots of blah blah.
Can anyone tell me how to do this? Or are there any really helpful links?
It IS possible, but only in one a bit hidden way. First I'll tell you about the alternative ways:
you have a conceptual error here. Timelines in Sequence diagram are not classes, but objects. So, they can't become classes.
Of course, a tool could have a function to create a class according to an object, as VP UML has. Obviously, EA has not such feature.
On the contrary, it is not a problem to drop a class on the sequence diagram to become a timeline. But EA has some conceptual problems with it, too. You have to make it an object here. Look also this.
On the other hand, there should be no problems to drop a timeline to the object diagram, but in EA it IS a problem - the object-timeline remains the timeline even on the Object diagram. That is obviously non-convenient and ununderstandable, but it is so. Obviously, it is one of these bugs that are called "features".
The same is behaviour of the timeline if we drop it on the Class Diagram. We even can't connect this object to a class by generalization - EA considers such connection as a rules breaking one.
And finally, how you CAN connect the timeline/object to a class. Right-click the timeline on the sequence diagram or its copy object on the class diagram. Go to Advanced. Choose Instance Classifier - the first menu item. There you can choose an existent class or even create a new one. And the object/timeline will belong to this very class.
You can't reach this feature from the Project Browser. It is obviously, another "feature" of the EA.
In a spec-adherent UML tool, one can assign classes (among other things) to a lifeline. I think that is why you are having difficulty converting lifelines into classes: they aren't the same kind of thing! Try creating classes first and assigning them to lifelines.
To transform sequence model into class model right-click on the package choose "Transform Current Package" => Check DDL => Select Transform
I hope this helps.
Regards,
Nabil

Project visualization in Lisp

Is there a tool that can generate diagrams (similar to Doxygen using Graphviz) but in the formats described by this paper: Lisp Looks Different
Program Style Distribution: Determine which programming style (Functional, OO, Imperative or Macro) dominates a software package, also to determine the size of complexity in each package.
Class Method Relation View: Visualizes the relationships between classes and methods (in Lisp, classes and methods are separated). The goal is to identify possible independent or loosely coupled components of the system.
Generic Concer View: Helps to identify and locate cross-cutting concerns associated with generic functions.
Class Type View: Helps to identify different types of classes, based on their structure, more precisely on the attributes to methods ratio.
tio
For the meaning of the colors and shapes, please refer to the document. It would be nice if there are equivalent tools for other languages as well.
Have you looked at Mondrian, which the paper cites was what was used to generate those diagrams?
More generally, have you looked at Moose, of which Mondrian is but a part?
I'm not sure I've seen one that produces diagrams exactly like those above, but there are quite a few more software visualization tools around.
Obvous first step: contact the paper's authors and ask what tools they used, and do they have any code they can share.