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Multiple inheritance alternativeI have several classes in my project:
varietyData gradeData attributeData TreeData Because the TreeData class encompasses each of the previous 3 classes, to me it would make the most sense to allow TreeData to inherit from each of them. Unfortunately, this is not possible in .NET. OK, fine. But what is the best alternative? Should I just add an instance of varietyData, gradeData and attributeData to the TreeData class? Is there any other way? Thanks On Tue, 03 Apr 2007 16:50:01 -0700, koulbassa <koulbassa@nospam.nospam>
wrote: > [...] I'm pretty aggregation is the only way. You can, however, include > OK, fine. But what is the best alternative? Should I just add an > instance of varietyData, gradeData and attributeData to the TreeData > class? > Is there any other way? multiple interfaces (an interface essentially being an abstract class) in a class definition. So if you define interfaces for each of the three base classes, then your TreeData class can inherit those interfaces. You would still need to implement the interfaces by including an instance of each of the three classes in TreeData (aggregation) and using those instances for calls to the interface methods. But at least you could use the TreeData class as if it were multiply inherited, even though it's not. If you don't use interfaces, then you still need to aggregate the classes, but then you would simply expose (as a property, most likely) the instances of the three base classes and access them that way. Pete Hi Koulbassa,
>Because the TreeData class encompasses each of the previous 3 classes, to me it would make the most sense to allow TreeData to inherit from each of them. Unfortunately, this is not possible in .NET. Yes, you're right. Multiple inheritance is not supported in .NET. However, we could implement multiple interfaces in one class. Could you tell me what the relationship among the varietyData, gradeData and attribute Data classes? What do you mean by "the TreeData class encompasses each of the previous 3 classes"? Does the TreeData class need to use the other three classes to implement its methods? In my opinion, if the four classes have "is-a" relationship among them, you should choose inheritance. On the other hand, if the previous three classes are not relevant, and the TreeData class has a "has-a" relationship to each of the other three classes, you could add instances of variableData, gradeData and attributeData classes to the TreeData class. In addition, you may add a public property for each of the above three instances. Thus, you could use the methods in the varietyData, or gradeData or attributeData class through the exposed instance of varietyData, or gradeData or attributeData, without the need to expose methods for the other three classes in the TreeData class. FYI, you may visit the following links for more information on when to use inheritance and interface: 'When to Use Inheritance' http://msdn2.microsoft.com/en-us/library/27db6csx(vs.71).aspx "When to Use Interfaces" http://msdn2.microsoft.com/en-us/library/3b5b8ezk(VS.71).aspx Hope this helps. If you have any question, please feel free to let me know. Sincerely, Linda Liu Microsoft Online Community Support ================================================== Get notification to my posts through email? Please refer to http://msdn.microsoft.com/subscriptions/managednewsgroups/default.aspx#notif ications. Note: The MSDN Managed Newsgroup support offering is for non-urgent issues where an initial response from the community or a Microsoft Support Engineer within 1 business day is acceptable. Please note that each follow up response may take approximately 2 business days as the support professional working with you may need further investigation to reach the most efficient resolution. The offering is not appropriate for situations that require urgent, real-time or phone-based interactions or complex project analysis and dump analysis issues. Issues of this nature are best handled working with a dedicated Microsoft Support Engineer by contacting Microsoft Customer Support Services (CSS) at http://msdn.microsoft.com/subscriptions/support/default.aspx. ================================================== This posting is provided "AS IS" with no warranties, and confers no rights. Hi Linda
Thank you for your response. You clarified my thinking by asking whether the relationships are 'is-a' or 'has-a'. It would appear that in this case inheritance may be ill-advised because the classes have 'has-a' relationships. Thanks for helping! Show quote "Linda Liu [MSFT]" wrote: > Hi Koulbassa, > > >Because the TreeData class encompasses each of the previous 3 classes, to > me it would make the most sense to allow TreeData to inherit from each of > them. Unfortunately, this is not possible in .NET. > > Yes, you're right. Multiple inheritance is not supported in .NET. However, > we could implement multiple interfaces in one class. > > Could you tell me what the relationship among the varietyData, gradeData > and attribute Data classes? > > What do you mean by "the TreeData class encompasses each of the previous 3 > classes"? Does the TreeData class need to use the other three classes to > implement its methods? > > In my opinion, if the four classes have "is-a" relationship among them, you > should choose inheritance. > > On the other hand, if the previous three classes are not relevant, and the > TreeData class has a "has-a" relationship to each of the other three > classes, you could add instances of variableData, gradeData and > attributeData classes to the TreeData class. In addition, you may add a > public property for each of the above three instances. Thus, you could use > the methods in the varietyData, or gradeData or attributeData class through > the exposed instance of varietyData, or gradeData or attributeData, without > the need to expose methods for the other three classes in the TreeData > class. > > FYI, you may visit the following links for more information on when to use > inheritance and interface: > > 'When to Use Inheritance' > http://msdn2.microsoft.com/en-us/library/27db6csx(vs.71).aspx > > "When to Use Interfaces" > http://msdn2.microsoft.com/en-us/library/3b5b8ezk(VS.71).aspx > > Hope this helps. > > If you have any question, please feel free to let me know. > > Sincerely, > Linda Liu > Microsoft Online Community Support > > ================================================== > Get notification to my posts through email? Please refer to > http://msdn.microsoft.com/subscriptions/managednewsgroups/default.aspx#notif > ications. > > Note: The MSDN Managed Newsgroup support offering is for non-urgent issues > where an initial response from the community or a Microsoft Support > Engineer within 1 business day is acceptable. Please note that each follow > up response may take approximately 2 business days as the support > professional working with you may need further investigation to reach the > most efficient resolution. The offering is not appropriate for situations > that require urgent, real-time or phone-based interactions or complex > project analysis and dump analysis issues. Issues of this nature are best > handled working with a dedicated Microsoft Support Engineer by contacting > Microsoft Customer Support Services (CSS) at > http://msdn.microsoft.com/subscriptions/support/default.aspx. > ================================================== > > This posting is provided "AS IS" with no warranties, and confers no rights. > >  |
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