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c# how do I pass a generic object to a forms constructor

Posted on 2013-05-23
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208 Views
Last Modified: 2013-06-06
For some reason, this wont' work

//wont work
        public FormXmlViewer(<T> objectToView)
//will work
        public FormXmlViewer(string objectAsStgring)
0
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Question by:jackjohnson44
  • 4
  • 4
9 Comments
 
LVL 42

Expert Comment

by:sedgwick
ID: 39193353
Try
Public class  FormXmlViewer<T> : Form{
public FormXmlViewer(T objectToView){
}

}
0
 

Author Comment

by:jackjohnson44
ID: 39194231
Thanks.

I tried what is below and my InitializeComponent is having an error.  Is this a problem if I want two constructors, one with a string and the other with a generic?


    public partial class FormXmlViewer<T> : Form
    {
        public FormXmlViewer(string xmlSource)
        {
            InitializeComponent();
        }
        public FormXmlViewer(T objectToView)
        {
            InitializeComponent();
        }
0
 
LVL 4

Expert Comment

by:AnuTiji
ID: 39198922
Hi

Instead of passing string as parameter, we can specify it as object and check the type before doing any function with the parameter.

public FormXmlViewer(object obj)
{
     InitializeComponent();
}
0
 

Author Comment

by:jackjohnson44
ID: 39204418
Thanks, but I don't want to specify the objects in the function.  My current form has an xml string.  I also have a deserialize function that you pass an object and get back a string.

So I can currently do:
string xmlString = GetStringFromObject(myObject)  //this uses generics and works with many objects
Form myForm(xmlString)

In this scenario I never have to know the type of object.  I want to avoid having to do this in two steps and also have to edit the form for each new object.
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LVL 42

Expert Comment

by:sedgwick
ID: 39204446
change this:
  public partial class FormXmlViewer<T> : Form
    {
        public FormXmlViewer(string xmlSource)
        {
            InitializeComponent();
        }
        public FormXmlViewer(T objectToView)
        {
            InitializeComponent();
        }

Open in new window


to this:

 
 public partial class FormXmlViewer<T> : Form
    {
        public FormXmlViewer(string xmlSource)
        {
            //deserialize xmlSource to T first, then call the 2nd ctor with the object.

        }
        public FormXmlViewer(T objectToView)
        {
            InitializeComponent();
        }

Open in new window

0
 
LVL 42

Accepted Solution

by:
sedgwick earned 500 total points
ID: 39204447
u can use this 2 functions to deserialize<T> from xmlsource:
public static T XmlDeserializeFromString<T>(string objectData)
{
    return (T)XmlDeserializeFromString(objectData, typeof(T));
}

public static object XmlDeserializeFromString(string objectData, Type type)
{
    var serializer = new XmlSerializer(type);
    object result;

    using (TextReader reader = new StringReader(objectData))
    {
        result = serializer.Deserialize(reader);
    }

    return result;
}
 

Open in new window


so u ended up with:
public partial class FormXmlViewer<T> : Form
    {
        public FormXmlViewer(string xmlSource)
        {
            //deserialize xmlSource to T first, then call the 2nd ctor with the object.
FormXmlViewer(XmlDeserializeFromString<T>(xmlSource))
        }
        public FormXmlViewer(T objectToView)
        {
            InitializeComponent();
        }

Open in new window

0
 

Author Comment

by:jackjohnson44
ID: 39204526
Thanks, I tried that.  Please see my comment above posted on 2013-05-24 at 08:25:59
0
 
LVL 42

Expert Comment

by:sedgwick
ID: 39204565
look closely what i've posted, only one constructor calls InitializeComponent()
0
 

Author Comment

by:jackjohnson44
ID: 39204582
Thanks, I didn't notice that.  Can you please explain why it isn't needed?  I just thought it was always required.
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