Does anyone know why there isn't a parameterless constructor for the
String type?
Given that you can...
Dim s as New String("Hello") ' inefficient, don't do this
I guess I would have expected...
Dim x as New String()
to give me x pointing the an empty string.
For what it's worth, the reason I came across this was because I was
trying to do this in a generic-based class...
Class XYZ(Of T)
Public Sub New()
If Not GetType(T).IsVa lueType Then
Dim ci As ConstructorInfo =
GetType(T).GetC onstructor(Syst em.Type.EmptyTy pes)
Dim obj As T = DirectCast(ci.I nvoke(Nothing), T)
Me.SetValue(obj )
End If
End Sub
And when I instantiated one of these of type String, I got the famous
NullReferenceEx ception because ci remained Nothing. The reason: String
has no constructor. I've sinced created a new exception for this class
to throw in such a case, but I still found it odd about String not
having a constructor without any arguments. I'm sure there's probably
a reason; I'm just not seeing it. 3 1624
On Oct 5, 4:29 pm, dippyk...@gmail .com wrote:
Does anyone know why there isn't a parameterless constructor for the
String type?
Given that you can...
Dim s as New String("Hello") ' inefficient, don't do this
I guess I would have expected...
Dim x as New String()
to give me x pointing the an empty string.
For what it's worth, the reason I came across this was because I was
trying to do this in a generic-based class...
Class XYZ(Of T)
Public Sub New()
If Not GetType(T).IsVa lueType Then
Dim ci As ConstructorInfo =
GetType(T).GetC onstructor(Syst em.Type.EmptyTy pes)
Dim obj As T = DirectCast(ci.I nvoke(Nothing), T)
Me.SetValue(obj )
End If
End Sub
And when I instantiated one of these of type String, I got the famous
NullReferenceEx ception because ci remained Nothing. The reason: String
has no constructor. I've sinced created a new exception for this class
to throw in such a case, but I still found it odd about String not
having a constructor without any arguments. I'm sure there's probably
a reason; I'm just not seeing it.
I believe it has to do with the String type being immutable, that is
it acts more like a value type than a reference type. Each time you
change a strings value, you actually create a new string, you don't
change the value of the old one.
Thanks. You're a good man. (ha)
Interestingly, whereas this doesn't work...
Dim x As String
x = New String()
this does...
Dim x as String
x = New String(Nothing)
and x becomes equal to "" (empty string)
There is *SO* much I don't understand.
On Oct 5, 4:53 pm, dippyk...@gmail .com wrote:
Thanks. You're a good man. (ha)
Interestingly, whereas this doesn't work...
Dim x As String
x = New String()
this does...
Dim x as String
x = New String(Nothing)
and x becomes equal to "" (empty string)
There is *SO* much I don't understand.
I always use "Dim x As String = String.Empty"
Thanks,
Seth Rowe This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics |
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**************************************
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//Iterate through the Assembly to find Class with a Public Interface.
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Hello All,
Is it considered a best practice to always write a parameterless constructor
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I'm not sure. I want my object to have all it absolutely requires to function
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created in an unstable state.
On the other hand
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I've stumbled on this restriction more than once, and I'd
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Let me mention two cases where I wanted parameterless
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on 23-9-2008, Julia B supposed :
Usually that errormessage means that you derived a class from a
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Always when you call a constructor, a constructor of a baseclass is
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one explicitly, the parameterless constructor is called automatically.
I don't know what the VB syntax is. In C# it would be something like:
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Solved it. I had to rewrite my classes in my business & datalayer changing
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Julia
"Julia B" wrote:
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