Nested Property

[Dark Kai]

Hi every1, need some help here with properties.
Im trying to group my properties like the property "Size" in a form which consist of width and height.
Thanks in advance

 

[Iceplug]

Cant you add something like
Public CSize As Size
in your class?
or
Public Property CSize() As Size
...
End Property
?

 

[Dark Kai]

Oh well, sure I can do that but I my property is not of type

 

[Nerseus]

You have to make your own struct or class and expose your property as one of that type.

Say your "property" is "Vector" with 3 subproperties "X", "Y" and "Z":

public struct Vector
{
    public double X;
    public double Y;
    public double Z;
}

public class MyClass
{
    public Vector Vector;
}

// Farther down in code:
MyClass c = new MyClass();
c.Vector.X = 1.0;
c.Vector.Y = 2.0;
c.Vector.Z = 3.0;

NOTE: In C# you can name a field the same as a type, as shown with "public Vector Vector" above. This is semi-common practice when you dont want to extend the Vector class but really just use it as a grouping mechanism for other properties. You cant do this in VB.NET as far as I know as it wont let you declare a variable like that (same name as the type). You might be able to name the struct "_Vector" or something similar, then name your property Vector.

-Nerseus

 

[Dark Kai]

Ive tried that already, but its just a blank property at the "property manager". Sort of readonly property and there is no + next to it for me to expend the property.

 

[mutant]

Are you looking for something like this? Im not entirely sure what you need.

define some class
Public Class MyOwnProperty
     declare some vars
     private _width as Integer
     private _height as integer
     now declare properties
     Public Property Width As Integer
     Get
          return _width
     End Get
     Set(ByVal Value As Integer)
          _width = Value
     End Set
     End Property
     Public Property Height As Integer
     Get
          return _height
     End Get
     Set(ByVal Value As Integer)
          _height = Value
     End Set
     End Property
End Class

and now use this class as a readonly property
Public Class ClassToUseProperty
     declare the previous class that was made
     private _myproperty As New MyOwnProperty
     And use the object as a read-only property
     Public ReadOnly Property TheProperty As MyOwnProperty
     Get
           return _myproperty
     End Get
     End Property
End Class

 

[Dark Kai]

hmmm I guess so I need to test this out first.
Thanks a lot.

 

[Dark Kai]

I tested the codes and its not working. well the results are the same as a readonly property and i cant access the Width and Height in the MyOwnProperty class.

 

[Nerseus]

Ah, you need this as a property on a Control, so that it shows up in the Properties window. Thats a bit different

Unfortunately, I dont know the right decoration to add to get that to work for a custom class. You might try divil as hes the resident Custom Control guru. Or try looking in the MSDN help custom attributes/decorations (things like [WebMethod] that you put before a function/property to tell the compiler to add extra info).

-Nerseus

 

[Procaine]

Public properties, readonly or not, will show up in the properties window of a custom control without any attributes.

Some of the attributes I use in this case are DescriptionAttribute (sets the description thats shown property window), CategoryAttribute (which category it comes under) and defaultvalueAttribute (when the property = DefaultValueAttribute, its non-bold in the property window; <> default value and its shown as bold).

 

[Nerseus]

I think he wants a custom object to show up in the properties window, complete with a little "+" to allow expanding and showing the variables of the subtype. Will that happen automatically?

-Nerseus

 

[Dark Kai]

Yah thats what i want.
Procaine, do you have any examples ??

 

[Procaine]

Sorry, no, I havent done this before, and I think I remember having trouble with it in the past.

If I get some time Ill take a look in to it and get a solution.

 

[Dark Kai]

Oh ok....Ill try looking up for more info. If any1 out there have an example on this pls let me know. Thanks to all that had contributed in this thread.