I have the following code (much simplified for this post). Note that
SessionKey uses DataAccess, and DataAccess requires SessionKey in it's
constructor.
Public Class SessionKey
Public IsValidSession as Boolean
Sub New(UserName, Password)
' Create session, including calls on DataAccess
' to validate username/password
IsValidSession = True
Dim DataAccess as New DataAccess(Me)
' Set IsValidSesion = False if usercode/password is invalid.
End Sub
End Class
Public Class DataAccess
Sub New(SessionKey)
If Not SessionKey.IsVa lidSession then
Throw New Exception ("Not a valid session!")
End If
End Sub
Function ExecuteSQL(SQL) As DataSet
'execute some SQL
End Function
End Class
It works great, but does this qualify as a circular dependency?
What's wrong with having a circular dependency in the first place?
Memory leaks? Performance problems? I understand that circular
dependencies can be a symptom of poorly designed class libraries, but
in this case, the class design seems fine. Should I take the time to
create a 3rd class that SessionKey and DataAccess inherit from?
Thanks,
Henry 1 2101
If you don't mind your class design, then it won't have a problem. Circular
dependencies can be a problem when the classes are in different assemblies.
Circular references used to be more a problem, but the GC handled them just
fine now. A recursive call might result in your classes if someone isn't
careful (suppose in one constructor, you call the other, and vice versa) --
however those will result in a stack overflow after taking full CPU for a
bit, so they'll be noticed when they happen.
-mike
MVP
"Henry Miller" <uw**@yahoo.com > wrote in message
news:49******** *************** ***@posting.goo gle.com... I have the following code (much simplified for this post). Note that SessionKey uses DataAccess, and DataAccess requires SessionKey in it's constructor.
Public Class SessionKey Public IsValidSession as Boolean
Sub New(UserName, Password) ' Create session, including calls on DataAccess ' to validate username/password
IsValidSession = True Dim DataAccess as New DataAccess(Me)
' Set IsValidSesion = False if usercode/password is invalid.
End Sub End Class
Public Class DataAccess Sub New(SessionKey) If Not SessionKey.IsVa lidSession then Throw New Exception ("Not a valid session!") End If End Sub
Function ExecuteSQL(SQL) As DataSet 'execute some SQL
End Function
End Class
It works great, but does this qualify as a circular dependency? What's wrong with having a circular dependency in the first place? Memory leaks? Performance problems? I understand that circular dependencies can be a symptom of poorly designed class libraries, but in this case, the class design seems fine. Should I take the time to create a 3rd class that SessionKey and DataAccess inherit from?
Thanks,
Henry This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics |
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I have the following code (much simplified for this post). Note that
SessionKey uses DataAccess, and DataAccess requires SessionKey in it's
constructor.
Public Class SessionKey
Public IsValidSession as Boolean
Sub New(UserName, Password)
' Create session, including calls on DataAccess
' to validate username/password
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