Passing properties by reference in C#

Question

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;     } } 

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.

Is it possible to pass a property by reference?

Answer 1

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

1. Return Value

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. Delegate

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 Expression

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. Reflection

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"); }