Get property in inerrited class

Chris Anderson

I'm trying to get the property from an inherited class without creating a new instance and rather use the parameter being passed in the method.

How can I get the property Color over here?

Does not work:

public void InitPlay(Toy toy)
{
Console.WriteLine($" The {TypeOfAnimal}{Name} is now playing with the {toy.Color} {toy} ");
}

Works:
This one works. But that's just because I created a new object of class Ball. But the point of passing in toy is thus redundant.

public void InitPlay(Toy toy)
{
Ball ball = new Ball();
Console.WriteLine($" The {TypeOfAnimal}{Name} is now playing with the {ball.Color} {toy} ");
}

Rest of the code (if needed)

class Ball : Toy
{
public string Color { get; set; }
}

abstract class Toy
{
...
}

5 Replies

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Ben Thompson5y ago
Note this'll depend on your object structure, but if not all Toy objects will have a color, consider subclassing Toy farther to give additional context:
abstract class Toy() { }

abstract class ColoredToy : Toy
{
public string Color { get; protected set; }
}

class Ball : ColoredToy { }

class Bone : ColoredToy { }

InitPlay(ColoredToy cToy)
{
Console.WriteLine(cToy.Color);
}
This way, so long as Ball or Bone (or whatever) is a ColoredToy, since InitPlay() accepts a ColoredToy, it'll be treated as such. InitPlay() will have access to all the members of cToy that it would have as both a Toy and a ColoredToy, but not any members it has as a Ball or Bone.

Note depending on what type of objects you're creating this approach may not be ideal. You may want to consider listing all the characteristics your Toys will have, seeing which ones overlap and to what extent, and from there determining the best object and inheritance structure to use.

Here's some additional information courtesy of Microsoft regarding interitance and class structure:
https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/classes-and-structs/inheritance

Here's also some information on interfaces, which can be used similarly:
https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/interfaces/
+3
Chris Anderson5y ago
@Ben Thompson
Yes, it would be optimal (and easier for me ) if all toys had Colors and were defined in the base class indeed. This however is redundant when not all toys need it.
Well I hear what you say and get it. I guess I'll just stick with the truth and accept that my solution isn't a working one...
+2
Ben Thompson5y ago
Attempting to access "Toy.Color" won't work because the object type Toy doesn't have a member called Color. Only Balls have a Color property.
In your second method, if the "toy" parameter you're passing is a Ball, you can cast it to a Ball and access the Color member in that manner:
Ball ball = (Ball)toy;
However, this only works if the Toy is a Ball--if it's a different class that's a subclass of Toy (like Bone), it won't work.
Consider how you're constructing your object--if every class that subtypes Toy will have a Color, it may make more sense for Color to be a (protected or public) member of Toy so the subclasses will have access to it.
As far as why InitPlay() treats the passed Ball as a Toy, it's because the parameter InitPlay() accepts is of type Toy, so any object passed to it must be of type Toy. Even if it's a subclass, it'll be treated as Toy and only the members of Toy will be accessible.
+3
Chris Anderson5y ago
Thanks for your clearification. I wonder though.
From the example below. How do I proceed? Is there any best practises on what I'm trying to achieve?

Example:
Here the variable selectedToy is assigned to ball and put into the method InitPlay()...
var selectedToy = (Toy)null;

Bone bone = new Bone();
selectedToy = bone;

Ball ball = new Ball();
selectedToy = ball; // Now the selectedToy is a ball which is the object being passed in...

InitPlay(selectedToy);
... but still I can't wrap my head around why it isn't the Ball object being passed in. When putting it into the method it is being cast to Toy? I sure see that Toy is the datatype but...
public void InitPlay(Toy toy) // Can Toy be set to an unspecific datatype?{
//public void InitPlay(Ball toy) // Having this line of code instead would work, but yet again, it's not always clear which of the inherited objects from Toy that's being passed in{

Console.WriteLine($" The {TypeOfAnimal}{Name} is now playing with the {toy.Color} {toy} ");
}
Sorry for being tardy but I don't get it :)
Thanks in advance!

EDIT: Do I have to make overloaded methods in order to get the right object in?
+2
Sachin Singh5y ago
Inheritence means child can access parents properties but parent can't access child properties.
Your child can access your money but you can't take your children's earnings.
In your example
color is the property of ball class which is child of Toy class.
so toy doesn't have color property , Ball will have every properties of Toy but Toy will have its own proprties only.
+4