Accessing one of many possible objects passed to a function

TNCaver

My question is in the code comment below:

public class MyBase
{
public string CommonProperty { get; set; }
}

public class ClassOne : MyBase
{
public string ClassOneProperty { get; set; }
}

public class ClassTwo : MyBase
{
public string ClassTwoProperty { get; set; }
}

public class program()
{
var classTwo = new ClassTwo();
classTwo.CommonProperty = "Some string";
classTwo.ClassTwoProperty = "Some other string";
TestFunction(classTwo);

private void TestFunction(object unknownClass)
{
// how do I convert unknownClass to its actual class and access its properties
// regardless of which type was passed to the function?
}
}

If you think 'goto' is evil, try writing an Assembly program without JMP.

Tony Hill

You could use the 'as' operator to try and cast it to a known type, if the cast works then you know the object type.

private static void TestFunction(object unknownClass)
{
    ClassOne c1 = unknownClass as ClassOne;

    if (c1 != null)
    {
        Console.WriteLine("Object is a ClassOne object");
    }
    else
    {
        Console.WriteLine("Object is not a ClassOne object");
    }

    ClassTwo c2 = unknownClass as ClassTwo;

    if (c2 != null)
    {
        Console.WriteLine("Object is a ClassTwo object");
    }
    else
    {
        Console.WriteLine("Object is not a ClassTwo object");
    }
}

Mycroft Holmes

GetType() will return the object name

	static void TestFunction(object unknownClass)
	{
		string sType = unknownClass.GetType().ToString();
		Console.WriteLine(sType);
		Console.ReadLine();
	}

Never underestimate the power of human stupidity - RAH I'm old. I know stuff - JSOP

TNCaver

What I'm trying to do is avoid duplicating code to access/manipulate the common properties. In TestFunction I want to be able to take unknownObject, cast it to its actual class type, and display or change its properties. Something like the following (which won't build):

private void TestFunction(object unknownClass)
{
var localObject = null;
string specificProperty = string.empty;

switch (unknownObject.GetType().Name)
{
case "ClassOne":
localObject = (ClassOne)unknownObject;
specificProperty = object.ClassOneProperty;
break;
case "ClassTwo":
localObject = (ClassTwo)unknownObject;
specificProperty = object.ClassTwoProperty;
break;
}

Console.PrintLine($"Common Property = {localObject.CommonProperty}, Specific Property = {specificProperty}.");
}

If you think 'goto' is evil, try writing an Assembly program without JMP.

TNCaver

Thank you, Tony. I'm trying to avoid duplicating code that accesses the properties common to all the objects passed to TestFunction. If you have a moment, please see my clarification in this thread.

If you think 'goto' is evil, try writing an Assembly program without JMP.

TNCaver

Thank you, Mycroft. I did know about getting the name and type, but that only gets me part way there. I'm trying to avoid duplicating code that accesses the properties common to all the objects passed to TestFunction. If you have a moment, please see my clarification in this thread.

If you think 'goto' is evil, try writing an Assembly program without JMP.

Mycroft Holmes

But you are not changing the common property in your example (except it may be because it is an example). Once you have the type I think there is something like String s = (unknownobject As ClassOne).CommonProperty

Never underestimate the power of human stupidity - RAH I'm old. I know stuff - JSOP

TNCaver

Okay, maybe I can work with that. Thanks.

If you think 'goto' is evil, try writing an Assembly program without JMP.

Lost User

string s1, s2;

if ( unknownClass is MyBase myBase ) {

s1 = myBase.CommonProperty;

if ( unknownClass is ClassOne one ) {
s2 = one.ClassOneProperty;

} else if ( unknownClass is ClassTwo two ) {
s2 = two.ClassTwoProperty;
}
}

"Before entering on an understanding, I have meditated for a long time, and have foreseen what might happen. It is not genius which reveals to me suddenly, secretly, what I have to say or to do in a circumstance unexpected by other people; it is reflection, it is meditation." - Napoleon I

Richard Deeming

Which version of C# / Visual Studio are you using?

private void TestFunction(object unknownClass)
{
(MyBase localObject, string specificProperty) = unknownClass switch
{
ClassOne c1 => (c1, c1.ClassOneProperty),
ClassTwo c2 => (c2, c2.ClassTwoProperty),
MyBase b => (b, null),
_ => (null, null),
};

if (localObject is null)
{
    Console.WriteLine($"Unknown object: {unknownClass}");
}
else
{
    Console.WriteLine($"Common Property = {localObject.CommonProperty}, Specific Property = {specificProperty}.");
}

}

"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer