How to get instance reference

7 Replies

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Vulpes15y ago
If you can clarify a bit more what you are looking for, I might still be able to help.
Poul Christiansen15y ago
Hi - not quite what I was looking for but it did give me an Idea - i'll tryto follow tht idea a little - thank you so far....
Vulpes15y ago
You could set fields on the actual instance as follows:

using System;
using System.Collections.Generic;
using System.Reflection;

public class FieldValuePair
{
public string Name {get; private set;}
public object Value {get; private set;}

public FieldValuePair(string name, object value)
{
Name = name;
Value = value;
}

public override string ToString()
{
return String.Format("{0} = {1}", Name, Value);
}
}

public class MyParentClass
{
protected int fieldC;

public MyParentClass(int c)
{
fieldC = c;
}
}

public class MyClass : MyParentClass
{
public string fieldA;
public DateTime fieldB;

public MyClass(string a, DateTime b, int c) : base(c)
{
fieldA = a;
fieldB = b;
}

public List Fields
{
get
{
List list = new List();
BindingFlags bf = BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic;
Type t = typeof(MyClass);
FieldInfo[] fia = t.GetFields(bf);

foreach(FieldInfo fi in fia)
{
FieldValuePair fvp = new FieldValuePair(fi.Name, fi.GetValue(this));
list.Add(fvp);
}

return list;
}

set
{
BindingFlags bf = BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic;
Type t = typeof(MyClass);

foreach(FieldValuePair fvp in value)
{
FieldInfo fi = t.GetField(fvp.Name, bf);
if (fi != null) fi.SetValue(this, fvp.Value);
}
}
}
}

class Program
{
static void Main()
{
MyClass mc = new MyClass("Hello", DateTime.Now, 42);
foreach(FieldValuePair fvp in mc.Fields)
{
Console.WriteLine(fvp);
}
Console.WriteLine();

List list = new List();
FieldValuePair fvpA = new FieldValuePair("fieldA","Goodbye");
list.Add(fvpA);
mc.Fields = list;
foreach(FieldValuePair fvp in mc.Fields)
{
Console.WriteLine(fvp);
}

Console.ReadKey();
}
}
Poul Christiansen15y ago
If I were to assign values to the fields using your approach - then that value would only be stored in the list - not on the instance of the class - is that correct? What would i need to do if i wanted it to update the field where the value came from on the instance?
Vulpes15y ago
I'm not sure what you mean by the field itself, unless you mean the FieldInfo object which is the field's representation in metadata.

Fields theselves are just slots within an object's memory allocation on the heap, which contain the current value of that field for that object.
Poul Christiansen15y ago
if i read your code correct - then this would give me access to the name and value of each field, but not the field itself.

I can now see that I need to write further requirements:
using a foreach (object f in Fields) I need to also be able to assign values that would the also affect the value on the class instance.

I'm sorry I didn't put that in my first question.
Vulpes15y ago
Try the following:

using System;
using System.Collections.Generic;
using System.Reflection;

public class FieldValuePair
{
public string Name {get; private set;}
public object Value {get; private set;}

public FieldValuePair(string name, object value)
{
Name = name;
Value = value;
}

public override string ToString()
{
return String.Format("{0} = {1}", Name, Value);
}
}

public class MyParentClass
{
protected int fieldC;

public MyParentClass(int c)
{
fieldC = c;
}
}

public class MyClass : MyParentClass
{
public string fieldA;
public DateTime fieldB;

public MyClass(string a, DateTime b, int c) : base(c)
{
fieldA = a;
fieldB = b;
}

public List Fields
{
get
{
List list = new List();
BindingFlags bf = BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic;
Type t = typeof(MyClass);
FieldInfo[] fia = t.GetFields(bf);

foreach(FieldInfo fi in fia)
{
FieldValuePair fvp = new FieldValuePair(fi.Name, fi.GetValue(this));
list.Add(fvp);
}

return list;
}
}
}

class Program
{
static void Main()
{
MyClass mc = new MyClass("Hello", DateTime.Now, 42);
foreach(FieldValuePair fvp in mc.Fields)
{
Console.WriteLine(fvp);
}

Console.ReadKey();
}
}