VB.NET

Constructor overloading problem

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Join Date: Jun 2007

Posts: 2

Reputation: pep_castefa is an unknown quantity at this point

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pep_castefa pep_castefa is offline

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Newbie Poster

Constructor overloading problem

Jun 7th, 2007

Hi all... I have a problem with constructor overloading in VB.NET and, I know how to solve it, but want to know the best way to do it... so here is the problem.
I have two manually created constructors in a class, like this...

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 VB.NET Syntax (Toggle Plain Text) 
 
Public Sub New(param1 As String)
...
End Sub
 
Public Sub New(param1 As String, param2 as String)
Me.New(param1)
...
End Sub
 
Public Sub New(param1 As String)
...
End Sub
 
Public Sub New(param1 As String, param2 as String)
Me.New(param1)
...
End Sub

and everything goes fine... until I try to do error catching like this

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 VB.NET Syntax (Toggle Plain Text) 
Public Sub New(param1 As String)
Try
...
Catch ex As Exception
Throw New Exception(...)
End Try
End Sub
 
Public Sub New(param1 As String, param2 as String)
Try
Me.New(param1)
...
Catch ex As Exception
Throw New Exception (...)
End Try
End Sub
Public Sub New(param1 As String)
Try
...
Catch ex As Exception
Throw New Exception(...)
End Try
End Sub
 
Public Sub New(param1 As String, param2 as String)
Try
Me.New(param1)
...
Catch ex As Exception
Throw New Exception (...)
End Try
End Sub

then, it says that, for the constructor with 2 parameters, the call to the other constructor has to be the first instruction to call... but that's not possible if I want to catch the errors produced by the first constructor (if I move the Me.New(param1) outside the Try then every error thrown by the first constructor will not be catched.
I know that if I create a function (for example _New()) and overload this one, then, from the constructors I can just call the function and everything is solved (no Me.New() called), but I don't know if this is the correct way to go.

Thanks in advance and sorry for my english (Im spanish)

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Join Date: Mar 2006

Posts: 122

Reputation: manal is an unknown quantity at this point

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manal

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Junior Poster

Re: Constructor overloading problem

Jun 8th, 2007

 Help with Code Tags 
 VB.NET Syntax (Toggle Plain Text) 
Public Sub New(param1 As String, param2 as String)
Me.New(param1)
Try
...
Catch ex As Exception
Throw New Exception (...)
End Try
End Sub
Public Sub New(param1 As String, param2 as String)
Me.New(param1)
Try
...
Catch ex As Exception
Throw New Exception (...)
End Try
End Sub

i think this will be enough , since the code of Me.New(param1) will be executed first , so u will catch the errors produced by the first constructor , right ?

"give only what u willing to receive "

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Join Date: Jun 2007

Posts: 2

Reputation: pep_castefa is an unknown quantity at this point

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pep_castefa pep_castefa is offline

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Re: Constructor overloading problem

Jun 11th, 2007

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Originally Posted by manal

Help with Code Tags

VB.NET Syntax (Toggle Plain Text)
Public Sub New(param1 As String, param2 as String)
Me.New(param1)
Try
...
Catch ex As Exception
Throw New Exception (...)
End Try
End Sub
Public Sub New(param1 As String, param2 as String) Me.New(param1) Try ... Catch ex As Exception Throw New Exception (...) End Try End Sub
i think this will be enough , since the code of Me.New(param1) will be executed first , so u will catch the errors produced by the first constructor , right ?

But, if the first constructor throws the exception, as the second has called Me.New(param1) outside the Try Catch Finally structure, the code crashes (the second constructor can't catch the exception produced by the first constructor called)