CODEWITHSUNDEEP
vb.netinheritanceinterface
AussieALF
AussieALF

Reputation: 339

Is this multiple inheritance? or another syntax for Inherits/Implements like C#?

I am trying to work out why this works

Public Interface IFullService
    Inherits ISerializableObjectLayerService, IVersionService
    <OperationContract()>
    Function StartTrac() As OperationResult(Of Boolean)
    <OperationContract()>
    Function StopTrac() As OperationResult(Of Boolean)
    <OperationContract()>
    Function IsTracRunning() As OperationResult(Of Boolean)
End Interface

An interface doesn't allow you to specify that it "implements" another interface, however in my case I needed to state that I have both interfaces, just by chance I put a comma in and entered the other interface, built and ran my unit tests and it works...

Previously I have been trying to follow a single inheritance tree such as

<ServiceContract()>
Public Interface IFullService
    Inherits IVersionService
    <OperationContract()>
    Function StartTrac() As OperationResult(Of Boolean)
    <OperationContract()>
    Function StopTrac() As OperationResult(Of Boolean)
    <OperationContract()>
    Function IsTracRunning() As OperationResult(Of Boolean)
End Interface

<ServiceContract()>
Public Interface IVersionService
    Inherits ISerializableObjectLayerService
    <OperationContract()>
    Function GetVersionsSince(ByVal VersionNumber As Long, IncludeBetas As Boolean) As OperationResult(Of Core.Setting.MemoryBmsReleaseInfo())
End Interface

As you can see here the IFullService inherits the IVersionService which then inherits the IVersionService. However in my case I needed a way for something to implement IVersionService without implementing the ISerializableObjectLayerService which is what lead me to my "working" solution.

Unfortunately I can't work out how to find out what exactly this is doing. I have search through stackoverflow, google, msdn and I can't find an example with Inherits ,

Could some guru please provide some information on what exactly this is accomplishing (would be great if you can provide a MSDN link), as I don't like doing something that I don't understand (as it can lead to problem in the future that you can work out :D)

Hopefully this question isn't too noobish :D

Upvotes: 1

Views: 266

Answers (2)

hatchet - done with SOverflow
hatchet - done with SOverflow

Reputation: 16259

Microsoft docs do mention it:

http://msdn.microsoft.com/en-us/library/ms173156.aspx

An interface itself can inherit from multiple interfaces.

Edit: Another link (All VB, with example), for an early edition of Visual Studio, but the information still applies.

http://msdn.microsoft.com/en-us/library/aa711871%28v=vs.71%29.aspx

Upvotes: 2

user541686
user541686

Reputation: 210485

Yes, it's multiple inheritance.

... of interfaces.

It means that any IFullService IS A(n) IVersionService. (When you see "any A is also a B", that's what "A inherits from B" means.)

Interface inheritance doesn't have any issues like multiple inheritance does, so MI is allowed. :)

Upvotes: 1

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