CODEWITHSUNDEEP
c#
user290043
user290043

Reputation:

C# stack overflow state

In my base class, the one that the others inherit from, has these properties:

private int DEFAULT_DISPLAY_ORDER = 999999;
private DateTime DEFAULT_DT = new DateTime(1111,1,1);

public int? Id {
    get 
    { 
        return Id.GetValueOrDefault(0);  
    }
    set 
    {
        if (DisplayOrder == null) DisplayOrder = DEFAULT_DISPLAY_ORDER;
        Id = value;
    }
}
public String Description { get; set; }
public int? DisplayOrder { get; set; }

But when I execute it, I get this error:

+ $exception {
     Cannot evaluate expression because the current thread is in a stack 
     overflow state.}
     System.Exception {System.StackOverflowException}

on line

if (DisplayOrder == null) DisplayOrder = DEFAULT_DISPLAY_ORDER;

What the heck is going on here?

Upvotes: 1

Views: 6223

Answers (6)

Bruno Costa
Bruno Costa

Reputation: 2720

You're creating a infinite loop, because you are referring to Id property in get and set of the Id property :P. So in get, you are getting to get the getting ;). And in the set, you are setting to set the setting. Weird huh? :)

Upvotes: 1

Justin
Justin

Reputation: 6559

When you call Id, it calls Id again recursively over and over.

return Id.GetValueOrDefault(0);

Upvotes: 0

Sergei Rogovtcev
Sergei Rogovtcev

Reputation: 5832

Id = value;

This does. You are doing recursive assignment to property inside the same property.

Upvotes: 0

Jon Skeet
Jon Skeet

Reputation: 1502536

Look at this:

public int? Id {
    get 
    { 
        return Id.GetValueOrDefault(0);  
    }

Here, accessing Id requires that you first fetch... Id. Bang.

Next:

set 
{
    if (DisplayOrder == null) DisplayOrder = DEFAULT_DISPLAY_ORDER;
    Id = value;
}

Look at the second part. In order to set Id, you have to... call the setter for Id. Bang.

You need a field for this:

private int? id;

// Now use the field in the property bodies
public int? Id {
    get 
    { 
        return id.GetValueOrDefault(0);  
    }
    set 
    {
        if (DisplayOrder == null) DisplayOrder = DEFAULT_DISPLAY_ORDER;
        id = value;
    }
}

Upvotes: 10

Ashley Grenon
Ashley Grenon

Reputation: 9565

ID = value will set off a loop. You should have a private variable like _id and use it in the setter and getter portions of the property.

Upvotes: 1

Charleh
Charleh

Reputation: 14002

You are calling Id from within itself - infinitely recursive... not good :)

public int? Id {
    get 
    { 
        return Id.GetValueOrDefault(0); // This will keep calling the getter of Id. You need a backing field instead.
    }
    set 
    {
        if (DisplayOrder == null) DisplayOrder = DEFAULT_DISPLAY_ORDER;
        Id = value; // And here...
    }
}

Upvotes: 3

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