Op donderdag 21 april 2005 03:58, schreef Kerry Raymond: > > Although multiple inheritance is allowed in UML 2.0 (I don't know > > about > > previous versions), it is stated as not recommended to use as many > > programming languages do not support multiple inheritence. > > Multiple inheritance has been provided in all versions of UML, and I am > unaware of any recommendation in a UML standard to avoid the use of > multiple inheritance. Could you please give me a more precise reference > to this recommendation?
I use a book as reference for UML, it is written by Jos Warmer and Anneke Kleppe. Both work for OMG for the UML 2.0 standard. The vice president of OMG, Andrew Watson has written a introduction in this book F.e. you can find information about them: http://www.klasse.nl/english/boeken/jos.html http://www.codegeneration.net/tiki-read_article.php?articleId=21 Google for their name + omg The book I use is in dutch, so it does not make much sense citing it here. It says that the use of multiple inheritance is discouraged as it makes a model more complex then needed. So it is a recommandation against multiple inheritance. What you write below, that some programming languages which are used a lot have problems with multiple inheritance is what I like to add from my own experience. Though, mostly there is a way to simulate multiple inheritance. But it is a simulation which, as I experience, needs other things to be done and can drive you away from pure OO-code. regards Bert Verhees > > There is some advice in the UML 2.0 standard regarding the use of > powertypes and their implementation in certain programming languages > (see para below). Could this be the recommendation you are thinking of? > If so, it is not a recommendation against multiple inheritance. > > "Power types are a conceptual, or analysis, notion. They express a > real-world situation. Implementing, however, them may > not be easy and efficient. To implement power types with a relational > database would mean that the instances of a relation > could also be relations in their own right. In object-oriented > implementations, the instances of a class could also be > classes. However, if the software implementation can not directly > support classes being objects and vice versa, redundant > structures must be defined. In other words, unless you're programming in > Smalltalk or CLOS, the designer must be aware > of the integrity problem of keeping the list of power type instances in > sync with the existing subclasses." > > Thanks > > Kerry > > Dr Kerry Raymond > Distinguished Research Leader > CRC for Enterprise Distributed Systems Technology > University of Queensland 4072 Australia > Ph: +61 7 3365 4310, Fax: +61 7 3365 4311, www.dstc.edu.au > > > - > If you have any questions about using this list, > please send a message to d.lloyd at openehr.org -- Met vriendelijke groet Bert Verhees ROSA Software - If you have any questions about using this list, please send a message to d.lloyd at openehr.org
