C# myths about best practices?

Question

My colleague keeps telling me of the things listed in comments.

I am confused. Can somebody please demystify these things for me?

class Bar
{
    private int _a;

    public int A
    {
        get { return _a; }
        set { _a = value; }
    }

    private Foo _objfoo;

    public Foo OFoo
    {
        get { return _objfoo; }
        set { _objfoo = value; }
    }

    public Bar(int a, Foo foo)
    {
        // this is a bad idea
        A = a;
        OFoo = foo;
    }

    // MYTHS
    private void Method()
    {
        this.A    //1 -
        this._a   //2 - use this when inside the class e.g. if(this._a == 2)
        A         //3 - use this outside the class e.g. barObj.A
        _a        //4 - 
                  // Not using this.xxx creates threading issues.
    }
}
class Foo
{
    // implementation
}

Answer 1

The this. is redundant if there isn't a name collision. You only need it when you need a reference to the current object or if you have an argument with the same name as a field.

Threading issues have nothing to do with it. The confusion maybe comes from the fact that most static members are implemented so that they are thread-safe and static members cannot (!) be called with this. since they aren't bound to the instance.

Answer 2

"Not using this.xxx creates threading issues"

is a complete myth. Just ask your co-worker to check the generate IL and have him explain why they are the same whether you add this or not.

"use this when inside the class e.g. if(this._a == 2)"

is down to what you want to achieve. What your co-worker seems to be saying is always reference the private field, which does not seem to me sensible. Often you want to access the public property, even inside a class, since the getter may modify the value (for instance, a property of type List may return a new List instance when the list is null to avoid null reference exceptions when accessing the property).