Syntax question

Sunchild · Apr 28, 2012

I have a control with a public array property and the array is assigned to default values. I'd like to allow the ASP.NET code to reassign a value within the array. I'm not sure of the ASP.NET syntax for array properties. Example: public class MyControl: Control { private Color[] fColors = {Color.Red, Color.Black, Color.Green}; public Color[] xColors { get( return fColors; } } } // end class ASP.NET: <Pref:MyControl id="MyID" runat="server" xColors[0]="Blue" /> Since xColors[0] doesn't work, what does work? --- PeterPart of your problem is that you've only defined a getter ( a public get method for the property ) so you have no way of assigning a new value to the private fColors array. Here's a new version of your code that includes a setter method definition: public class MyControl : Control { private Color[] fColors = {Color.Red, Color.Black, Color.Green}; public Color[] xColors { get( return fColors ; ) set( fColors = value ; ) } } // end class See how I added a *setter* into the public property definition? The getter enables you to get the hashtable (duh!) and the setter enables you to update it. In your ASP page you could do something akin to this: ' Server-side code ------------------------ Color[] myColors = MyID.xColors ; // retrieve the array myColors[0] = Color.Blue ; // update the element MyID.xColors = myColors ; // set the property of the control ' Webcontrol definition ------------------------ <Pref:MyControl id="MyID" runat="server" /> This is totally untested, but I hope that it will give you some idea of how it should work. Please lookup the correct syntax for these methods in MSDN or on http://samples.gotdotnet.com/quickstart. If you'd like to see an even cooler way, do a search in MSDN on C# indexers OR VB Default Properties, they will allow you to write code similar to this: ' Server-side code ------------------------ (Color) MyID[0] = Color.Blue ;Digory, Thank you for taking the time to answer my question. I have two concerns with your answer: 1. I used a readonly (GET) property because I was thinking that the array is another object, already created by the "new" operator. (int[] vMyInt = new int[10]) Thus the GET returns the reference to the object. The caller needs to retrieve the reference to the object then use its methods, of which the [] is an overloaded operator. The only reason to supply a SET function is when you intend to allow the user to reassign the entire array object. Do you agree? 2. I was hoping for the syntax of the ASP.NET code within the <asp:control id=...> line for assigning a value to an array or a confirmation that this isn't possible. I have also looked at Indexers and while they seem appropriate, they have several problems: 1. They have a fixed naming scheme, limiting their clarity. 2. There can only be one per class. 3. I cannot find the ASP.NET syntax for them either. Any direction would be greatly appreciated. --- PeterPeter, > The only reason to supply a SET function is when you > intend to allow the user to reassign the entire array > object. Do you agree? Yep, I do agree... see what happens when I talk about something I don't understand. > I was hoping for the syntax of the ASP.NET code within > the <asp:control id=...> line for assigning a value to > an array or a confirmation that this isn't possible. Well, in light of what I've said previously, I probably shouldn't comment, but, I'm pretty sure that it isn't possible. > 3. I cannot find the ASP.NET syntax for them either. This I can help you with ( for VB anyways )... -------------------------------------- CODE INSIDE YOUR USER CONTROL -------------------------------------- Private fColors As System.Drawing.Color() = {Color.Red, Color.Black, Color.Green} Public ReadOnly Property xColors() As System.Drawing.Color() Get Return fColors End Get End Property Default Public Property Colors(ByVal Item As Int32) As System.Drawing.Color Get Return fColors(Item) End Get Set(ByVal Value As System.Drawing.Color) fColors(Item) = Value End Set End Property -------------------------------------- CONSUMING CODE -------------------------------------- ' USING THE PUBLIC (PARAMETERLESS) PROPERTY Dim myColors As Color() = MyID.xColors myColors(0) = Color.Blue ' USING THE DEFAULT (PARAMETERFUL) PROPERTY MyID(0) = Color.Blue -------------------------------------- Parameterful properties (indexers and default properties) are well covered in the MSPress book titled "OOP with VB.NET and C# Step by Step": http://www.amazon.com/exec/obidos/ASIN/0735615683/forestlakewebser/

Syntax question

Sunchild

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