Clean elegant solution to form-class level component collection initializing before Initialize Component?
I am converting an old Vb6 solution to .net 2.0 in vs2010. I've been working in C# for about 3 years now and .net for 5. I don't recall having this problem in C#
, but if I want initialize a readonly
collection of DerivedControlFoo
Is there a clean way to do it besides creating a sub to do it all off somewhere else? I'd love to be able to do it at the class level at the declaration for readability and simplicity.
Example:
Private _formattedFormulaText As IEnumerable(Of Label) = New List(Of Label) From { _
FormulaLabels0, FormulaLabels1, lblBrownFormula, FormulaLa开发者_StackOverflowbels3, lblGreenFormula, _
lblOrangeFormula, lblRedFormula, FormulaLabels7, lblFormulaTotal}
Doing it the straightforward easy way, results in the collection being filled with {nothing,..,nothing}
This is not thread safe, but works very well for my purposes:
Solution in use:
Private _formattedFormulaText As New Lazy(Of IEnumerable(Of Label))(Function() New List(Of Label) From { _
FormulaLabels0, FormulaLabels1, lblBrownFormula, FormulaLabels3, lblGreenFormula, _
lblOrangeFormula, lblSRedFormula, FormulaLabels7, lblFormulaTotal})
drawbacks - all code touching the variable has to add an accessor .value
. My code has 5 of these lazy collections and 1-2 touchpoints per collection usually in the same function.
Drawback illustration:
Dim clearText = Sub(c As Control) c.Text = String.Empty
_formattedFormulaText.ToList.ForEach(clearText)
becomes
Dim clearText = Sub(c As Control) c.Text = String.Empty
_formattedFormulaText.Value.ToList.ForEach(clearText)
Not compliant with good practices for debugger display used in .net 4, but would be easy to add in using reflector
Please note a property could have been used to eliminate the need to .value in the touchpoints:
Private ReadOnly Property FormattedText As IEnumerable(Of Label)
Get
Return _formattedFormulaText.Value
End Get
End Property
supporting class:
''' <summary>
''' translated from http://msdn.microsoft.com/en-us/vcsharp/bb870976.aspx
''' </summary>
Public Class Lazy(Of T)
Private _func As Func(Of T)
Private _result As T
Private _hasValue As Boolean
Public Sub New(ByVal func As Func(Of T))
_func = func
_hasValue = False
End Sub
Public ReadOnly Property Value As T
Get
If Me._hasValue = False Then
_result = _func()
_hasValue = True
End If
Return _result
End Get
End Property
End Class
design based on MSDN's article Lazy Computation in C# Also with assistance from Reflector against
assembly\NativeImages_v4.0.30319_32\mscorlib\246f1a5abb686b9dcdf22d3505b08cea\mscorlib.ni.dll
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