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InheritanceI have the following Classes: ******************************************* Public Class AuthHeader:Inherits SoapHeader Public AuthHeaderName As String Public SessionKey As String = "Default" End Class Public Class ServiceTicket:Inherits AuthHeader Public IsAuthenticated As Boolean Public SessionKey As String = "Default from ServiceTicket" Public Expiration As DateTime End Class Public Class TempClass1:Inherits ServiceTicket Public TomsClass1Name As String End Class ***************************************** I assume that inheritance depends on the order of definition. Here SessionKey is being defined in 2 classes. For TempClass1 and ServiceTicket, Session would be "Default from ServiceTicket" since it would have been defined second. So if I create TempClass1, it would work something like, SessionKey would first be "Default" but then ServiceTicket would re-define it, since it inherited it (and is higher up the chain) and change it to "Default from ServiceTicket". In this case, if I had: Dim objTempClass1 As new TempClass1 Dim objServiceTicket As new ServiceTicket Dim objAuthHeader As new AuthHeader objTempClass1.SessionKey = "Default from ServiceTicket" ' Inherited from ServiceKey objServiceKey.SessionKey = "Default from ServiceTicket" objAuthHeader.SessionKey = "Default" But if I took out the Sessionkey from the ServiceKey class that it would be: objTempClass1.SessionKey = "Default" ' Inherited from AuthHeader objServiceKey.SessionKey = "Default" ' Inherited from AuthHeader objAuthHeader.SessionKey = "Default" Also, I originally got this from a sample program that didn't set the defaults, but had it defined as: ******************************************* Public Class AuthHeader:Inherits SoapHeader Public AuthHeaderName As String Public SessionKey As String End Class Public Class ServiceTicket:Inherits AuthHeader Public IsAuthenticated As Boolean Public SessionKey As String Public Expiration As DateTime End Class Public Class TempClass1:Inherits ServiceTicket Public TomsClass1Name As String End Class ***************************************** Is there any good reason to defining SessionKey again ServiceTicket? I assume since it always would inherit from AuthHeader, it would always get SessionKey from the inheritance. If it wanted to set SessionKey in ServiceTicket, it could just set it by: SessionKey = "Default" without needing to redefine it. Is this correct? Thanks, Tom yes the reason to override are more applicable to methods, properties yes..
if you want to additional functionality to than what is available in the base class.. I also strongly recommend that any public variables you declare and intended to use a property or have thought it must be overridden, given them as property definitions its much cleaner that way VJ Show quoteHide quote "tshad" <tscheider***@ftsolutions.com> wrote in message news:u$wTCq2VGHA.5808@TK2MSFTNGP12.phx.gbl... >I am playing with Inheritance and want to make sure I understand it. > > I have the following Classes: > ******************************************* > Public Class AuthHeader:Inherits SoapHeader > Public AuthHeaderName As String > Public SessionKey As String = "Default" > End Class > > Public Class ServiceTicket:Inherits AuthHeader > Public IsAuthenticated As Boolean > Public SessionKey As String = "Default from ServiceTicket" > Public Expiration As DateTime > End Class > > Public Class TempClass1:Inherits ServiceTicket > Public TomsClass1Name As String > End Class > ***************************************** > > I assume that inheritance depends on the order of definition. > > Here SessionKey is being defined in 2 classes. For TempClass1 and > ServiceTicket, Session would be "Default from ServiceTicket" since it > would have been defined second. So if I create TempClass1, it would work > something like, SessionKey would first be "Default" but then ServiceTicket > would re-define it, since it inherited it (and is higher up the chain) and > change it to "Default from ServiceTicket". > > In this case, if I had: > > Dim objTempClass1 As new TempClass1 > Dim objServiceTicket As new ServiceTicket > Dim objAuthHeader As new AuthHeader > > objTempClass1.SessionKey = "Default from ServiceTicket" ' > Inherited from ServiceKey > objServiceKey.SessionKey = "Default from ServiceTicket" > objAuthHeader.SessionKey = "Default" > > But if I took out the Sessionkey from the ServiceKey class that it would > be: > > objTempClass1.SessionKey = "Default" ' Inherited > from AuthHeader > objServiceKey.SessionKey = "Default" ' Inherited > from AuthHeader > objAuthHeader.SessionKey = "Default" > > Also, I originally got this from a sample program that didn't set the > defaults, but had it defined as: > ******************************************* > Public Class AuthHeader:Inherits SoapHeader > Public AuthHeaderName As String > Public SessionKey As String > End Class > > Public Class ServiceTicket:Inherits AuthHeader > Public IsAuthenticated As Boolean > Public SessionKey As String > Public Expiration As DateTime > End Class > > Public Class TempClass1:Inherits ServiceTicket > Public TomsClass1Name As String > End Class > ***************************************** > > Is there any good reason to defining SessionKey again ServiceTicket? > > I assume since it always would inherit from AuthHeader, it would always > get SessionKey from the inheritance. If it wanted to set SessionKey in > ServiceTicket, it could just set it by: > > SessionKey = "Default" > > without needing to redefine it. > > Is this correct? > > Thanks, > > Tom > > "Vijay" <vi***@msdiscussions.com> wrote in message I agree.news:e4p7432VGHA.4416@TK2MSFTNGP15.phx.gbl... > yes the reason to override are more applicable to methods, properties > yes.. if you want to additional functionality to than what is available in > the base class.. I also strongly recommend that any public variables you > declare and intended to use a property or have thought it must be > overridden, given them as property definitions its much cleaner that way This was just a quick example of the what I was trying to play with. I just wanted to make sure I was understanding what was happening correctly. I wasn't sure if there was 1 variable or 2. I assume it was 1 and the last defined one was the one I would see. I heard from someone else that if I wanted 2 variables I would define it as shadows (override being the default). I would still get the last defined one, but I could also get the one in the base class by using the base class name with the variable. Not sure why I would need that, but I am sure there are good reasons for it. Right now I am just trying to get the basics of inheritance down. I understand it, I just haven't build any objects that were inherited by another object (other than the normal system ones). Thanks, Tom Show quoteHide quote > > VJ > > "tshad" <tscheider***@ftsolutions.com> wrote in message > news:u$wTCq2VGHA.5808@TK2MSFTNGP12.phx.gbl... >>I am playing with Inheritance and want to make sure I understand it. >> >> I have the following Classes: >> ******************************************* >> Public Class AuthHeader:Inherits SoapHeader >> Public AuthHeaderName As String >> Public SessionKey As String = "Default" >> End Class >> >> Public Class ServiceTicket:Inherits AuthHeader >> Public IsAuthenticated As Boolean >> Public SessionKey As String = "Default from ServiceTicket" >> Public Expiration As DateTime >> End Class >> >> Public Class TempClass1:Inherits ServiceTicket >> Public TomsClass1Name As String >> End Class >> ***************************************** >> >> I assume that inheritance depends on the order of definition. >> >> Here SessionKey is being defined in 2 classes. For TempClass1 and >> ServiceTicket, Session would be "Default from ServiceTicket" since it >> would have been defined second. So if I create TempClass1, it would work >> something like, SessionKey would first be "Default" but then >> ServiceTicket would re-define it, since it inherited it (and is higher up >> the chain) and change it to "Default from ServiceTicket". >> >> In this case, if I had: >> >> Dim objTempClass1 As new TempClass1 >> Dim objServiceTicket As new ServiceTicket >> Dim objAuthHeader As new AuthHeader >> >> objTempClass1.SessionKey = "Default from ServiceTicket" ' >> Inherited from ServiceKey >> objServiceKey.SessionKey = "Default from ServiceTicket" >> objAuthHeader.SessionKey = "Default" >> >> But if I took out the Sessionkey from the ServiceKey class that it would >> be: >> >> objTempClass1.SessionKey = "Default" ' Inherited >> from AuthHeader >> objServiceKey.SessionKey = "Default" ' Inherited >> from AuthHeader >> objAuthHeader.SessionKey = "Default" >> >> Also, I originally got this from a sample program that didn't set the >> defaults, but had it defined as: >> ******************************************* >> Public Class AuthHeader:Inherits SoapHeader >> Public AuthHeaderName As String >> Public SessionKey As String >> End Class >> >> Public Class ServiceTicket:Inherits AuthHeader >> Public IsAuthenticated As Boolean >> Public SessionKey As String >> Public Expiration As DateTime >> End Class >> >> Public Class TempClass1:Inherits ServiceTicket >> Public TomsClass1Name As String >> End Class >> ***************************************** >> >> Is there any good reason to defining SessionKey again ServiceTicket? >> >> I assume since it always would inherit from AuthHeader, it would always >> get SessionKey from the inheritance. If it wanted to set SessionKey in >> ServiceTicket, it could just set it by: >> >> SessionKey = "Default" >> >> without needing to redefine it. >> >> Is this correct? >> >> Thanks, >> >> Tom >> >> > > Personally I will try to avoid shadows.. as much as I can.. it just causes
confusion in readability. That is what I have seen in huge projects.. Vijay Show quoteHide quote "tshad" <tscheider***@ftsolutions.com> wrote in message news:eProSo3VGHA.4724@TK2MSFTNGP09.phx.gbl... > "Vijay" <vi***@msdiscussions.com> wrote in message > news:e4p7432VGHA.4416@TK2MSFTNGP15.phx.gbl... >> yes the reason to override are more applicable to methods, properties >> yes.. if you want to additional functionality to than what is available >> in the base class.. I also strongly recommend that any public variables >> you declare and intended to use a property or have thought it must be >> overridden, given them as property definitions its much cleaner that way > > I agree. > > This was just a quick example of the what I was trying to play with. I > just wanted to make sure I was understanding what was happening correctly. > > I wasn't sure if there was 1 variable or 2. I assume it was 1 and the > last defined one was the one I would see. > > I heard from someone else that if I wanted 2 variables I would define it > as shadows (override being the default). I would still get the last > defined one, but I could also get the one in the base class by using the > base class name with the variable. Not sure why I would need that, but I > am sure there are good reasons for it. Right now I am just trying to get > the basics of inheritance down. I understand it, I just haven't build any > objects that were inherited by another object (other than the normal > system ones). > > Thanks, > > Tom >> >> VJ >> >> "tshad" <tscheider***@ftsolutions.com> wrote in message >> news:u$wTCq2VGHA.5808@TK2MSFTNGP12.phx.gbl... >>>I am playing with Inheritance and want to make sure I understand it. >>> >>> I have the following Classes: >>> ******************************************* >>> Public Class AuthHeader:Inherits SoapHeader >>> Public AuthHeaderName As String >>> Public SessionKey As String = "Default" >>> End Class >>> >>> Public Class ServiceTicket:Inherits AuthHeader >>> Public IsAuthenticated As Boolean >>> Public SessionKey As String = "Default from ServiceTicket" >>> Public Expiration As DateTime >>> End Class >>> >>> Public Class TempClass1:Inherits ServiceTicket >>> Public TomsClass1Name As String >>> End Class >>> ***************************************** >>> >>> I assume that inheritance depends on the order of definition. >>> >>> Here SessionKey is being defined in 2 classes. For TempClass1 and >>> ServiceTicket, Session would be "Default from ServiceTicket" since it >>> would have been defined second. So if I create TempClass1, it would >>> work something like, SessionKey would first be "Default" but then >>> ServiceTicket would re-define it, since it inherited it (and is higher >>> up the chain) and change it to "Default from ServiceTicket". >>> >>> In this case, if I had: >>> >>> Dim objTempClass1 As new TempClass1 >>> Dim objServiceTicket As new ServiceTicket >>> Dim objAuthHeader As new AuthHeader >>> >>> objTempClass1.SessionKey = "Default from ServiceTicket" ' >>> Inherited from ServiceKey >>> objServiceKey.SessionKey = "Default from ServiceTicket" >>> objAuthHeader.SessionKey = "Default" >>> >>> But if I took out the Sessionkey from the ServiceKey class that it would >>> be: >>> >>> objTempClass1.SessionKey = "Default" ' Inherited >>> from AuthHeader >>> objServiceKey.SessionKey = "Default" ' Inherited >>> from AuthHeader >>> objAuthHeader.SessionKey = "Default" >>> >>> Also, I originally got this from a sample program that didn't set the >>> defaults, but had it defined as: >>> ******************************************* >>> Public Class AuthHeader:Inherits SoapHeader >>> Public AuthHeaderName As String >>> Public SessionKey As String >>> End Class >>> >>> Public Class ServiceTicket:Inherits AuthHeader >>> Public IsAuthenticated As Boolean >>> Public SessionKey As String >>> Public Expiration As DateTime >>> End Class >>> >>> Public Class TempClass1:Inherits ServiceTicket >>> Public TomsClass1Name As String >>> End Class >>> ***************************************** >>> >>> Is there any good reason to defining SessionKey again ServiceTicket? >>> >>> I assume since it always would inherit from AuthHeader, it would always >>> get SessionKey from the inheritance. If it wanted to set SessionKey in >>> ServiceTicket, it could just set it by: >>> >>> SessionKey = "Default" >>> >>> without needing to redefine it. >>> >>> Is this correct? >>> >>> Thanks, >>> >>> Tom >>> >>> >> >> > > 
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