属性get调用何时创建引用类型的本地副本?如何避免?

在班上 fooBase 有 SomeProperty barBase ,我有一个类型为 :

public class fooBase 
{
    public object SomeProperty { get; set; }
}

public class barBase
{
    protected fooBase _foo;
}

很明显,在巴巴多斯我可以通过 _foo.SomeProperty = whatever; .

现在在派生类中 fooChild 派生类基于一些不重要的逻辑 barChild 操作。barChild构造函数获取fooChild的实例并存储它。

public class fooChild : fooBase { /* someLogic */ }

public class barChild : barBase
{
    public barChild(fooChild foo)
    {
        _foo = foo; // foo of [fooChild] type stored in _foo of [fooBase] type.
    }

    protected fooChild _getFoo // cast via 'as' to access fooChild logic
    { get { return _foo as fooChild; } }
}

_foo as fooChild (哪个 _getFoo

问题 :将 get { return ... as ... } SomeFunction()

public class somewhereElse : barChild
{
    public void SomeFunction()
    {
        _getFoo.SomeProperty = new object();
        // now barBase:_foo.SomeProperty is still old object?
    }
}

如果是,我怎样才能避免呢?
如果没有,我怎么知道?