Why doesn't the C# compiler stop properties from referring to themselves?

Question

If I do this I get a System.StackOverflowException:

private string abc = "";
public string Abc
{
    get
    { 
        return Abc; // Note the mistaken capitalization
    }
}

I understand why -- the property is referencing itself, leading to an infinite loop. (See previous questions here and here).

What I'm wondering (and what I didn't see answered in those previous questions) is why doesn't the C# compiler catch this mistake? It checks for some other kinds of circular reference (classes inheriting from themselves, etc.), right? Is it just that this mistake wasn't common enough to be worth checking for? Or is there some situation I'm not thinking of, when you'd want a property to actually reference itself in this way?

question from:https://stackoverflow.com/questions/2336847/why-doesnt-the-c-sharp-compiler-stop-properties-from-referring-to-themselves

Answer 1

You can see the "official" reason in the last comment here.

Posted by Microsoft on 14/11/2008 at 19:52

Thanks for the suggestion for Visual Studio!

You are right that we could easily detect property recursion, but we can't guarantee that there is nothing useful being accomplished by the recursion. The body of the property could set other fields on your object which change the behavior of the next recursion, could change its behavior based on user input from the console, or could even behave differently based on random values. In these cases, a self-recursive property could indeed terminate the recursion, but we have no way to determine if that's the case at compile-time (without solving the halting problem!).

For the reasons above (and the breaking change it would take to disallow this), we wouldn't be able to prohibit self-recursive properties.

Alex Turner

Program Manager

Visual C# Compiler