在 C# 中通过引用传递属性 [英] Passing properties by reference in C#

问题描述

我正在尝试执行以下操作:

I'm trying to do do the following:

GetString(
    inputString,
    ref Client.WorkPhone)

private void GetString(string inValue, ref string outValue)
{
    if (!string.IsNullOrEmpty(inValue))
    {
        outValue = inValue;
    }
}

这给了我一个编译错误.我认为我想要达到的目标非常清楚.基本上我希望 GetString 将输入字符串的内容复制到 Client 的 WorkPhone 属性.

This is giving me a compile error. I think its pretty clear what I'm trying to achieve. Basically I want GetString to copy the contents of an input string to the WorkPhone property of Client.

是否可以通过引用传递属性?

Is it possible to pass a property by reference?

推荐答案

属性不能通过引用传递.您可以通过以下几种方法来解决此限制.

Properties cannot be passed by reference. Here are a few ways you can work around this limitation.

string GetString(string input, string output)
{
    if (!string.IsNullOrEmpty(input))
    {
        return input;
    }
    return output;
}

void Main()
{
    var person = new Person();
    person.Name = GetString("test", person.Name);
    Debug.Assert(person.Name == "test");
}

2.委托

void GetString(string input, Action<string> setOutput)
{
    if (!string.IsNullOrEmpty(input))
    {
        setOutput(input);
    }
}

void Main()
{
    var person = new Person();
    GetString("test", value => person.Name = value);
    Debug.Assert(person.Name == "test");
}

3.LINQ 表达式

void GetString<T>(string input, T target, Expression<Func<T, string>> outExpr)
{
    if (!string.IsNullOrEmpty(input))
    {
        var expr = (MemberExpression) outExpr.Body;
        var prop = (PropertyInfo) expr.Member;
        prop.SetValue(target, input, null);
    }
}

void Main()
{
    var person = new Person();
    GetString("test", person, x => x.Name);
    Debug.Assert(person.Name == "test");
}

4.反思

void GetString(string input, object target, string propertyName)
{
    if (!string.IsNullOrEmpty(input))
    {
        var prop = target.GetType().GetProperty(propertyName);
        prop.SetValue(target, input);
    }
}

void Main()
{
    var person = new Person();
    GetString("test", person, nameof(Person.Name));
    Debug.Assert(person.Name == "test");
}

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