这在c#语言规范的7.4.1节中介绍。只有变量引用可以作为参数列表中的ref或out形参传递。属性不符合变量引用的条件，因此不能使用。

这在c#语言规范的7.4.1节中介绍。只有变量引用可以作为参数列表中的ref或out形参传递。属性不符合变量引用的条件，因此不能使用。

如果函数在您的代码中，并且您可以修改它，那么接受的答案是好的。但有时你必须使用某个外部库中的对象和函数，你不能改变属性和函数定义。然后你可以使用一个临时变量。

var phone = Client.WorkPhone;
GetString(input, ref phone);
Client.WorkPhone = phone;

Another trick not yet mentioned is to have the class which implements a property (e.g. Foo of type Bar) also define a delegate delegate void ActByRef<T1,T2>(ref T1 p1, ref T2 p2); and implement a method ActOnFoo<TX1>(ref Bar it, ActByRef<Bar,TX1> proc, ref TX1 extraParam1) (and possibly versions for two and three "extra parameters" as well) which will pass its internal representation of Foo to the supplied procedure as a ref parameter. This has a couple of big advantages over other methods of working with the property:

The property is updated "in place"; if the property is of a type that's compatible with `Interlocked` methods, or if it is a struct with exposed fields of such types, the `Interlocked` methods may be used to perform atomic updates to the property. If the property is an exposed-field structure, the fields of the structure may be modified without having to make any redundant copies of it. If the `ActByRef` method passes one or more `ref` parameters through from its caller to the supplied delegate, it may be possible to use a singleton or static delegate, thus avoiding the need to create closures or delegates at run-time. The property knows when it is being "worked with". While it is always necessary to use caution executing external code while holding a lock, if one can trust callers not to do too do anything in their callback that might require another lock, it may be practical to have the method guard the property access with a lock, such that updates which aren't compatible with `CompareExchange` could still be performed quasi-atomically.

过去的事情被引用是一个极好的模式;可惜它没有被更多地使用。

看起来，您需要对该字段施加业务规则约束，同时又希望使您的代码尽可能地保持DRY。

它是可以实现的，也可以通过在字段上实现一个完整的属性并使用您的可重用方法来保存您的域语义:

public class Client
{
    private string workPhone;

    public string WorkPhone
    {
        get => workPhone;
        set => SafeSetString(ref workPhone, value);
    }

    private void SafeSetString(ref string target, string source)
    {
        if (!string.IsNullOrEmpty(source))
        {
            target = source;
        }
    }
}

SafeSetString方法可以放在Utilities类中或任何有意义的地方。

如果你想同时获取和设置属性，你可以在c# 7中使用这个:

GetString(
    inputString,
    (() => client.WorkPhone, x => client.WorkPhone = x))

void GetString(string inValue, (Func<string> get, Action<string> set) outValue)
{
    if (!string.IsNullOrEmpty(outValue.get()))
    {
        outValue.set(inValue);
    }
}