Question

I know I could have an attribute but that’s more work than I want to go to… and not general enough.

I want to do something like

class Whotsit {     private string testProp = 'thingy';      public string TestProp      {         get { return testProp; }         set { testProp = value; }     }  }  ...  Whotsit whotsit = new Whotsit(); string value = GetName(whotsit.TestProp); //precise syntax up for grabs.. 

where I’d expect value to equal ‘TestProp’

but I can’t for the life of me find the right reflection methods to write the GetName method…

EDIT: Why do I want to do this? I have a class to store settings read from a ‘name’, ‘value’ table. This is populated by a generalised method based upon reflection. I’d quite like to write the reverse…

/// <summary> /// Populates an object from a datatable where the rows have columns called NameField and ValueField.  /// If the property with the 'name' exists, and is not read-only, it is populated from the  /// valueField. Any other columns in the dataTable are ignored. If there is no property called /// nameField it is ignored. Any properties of the object not found in the data table retain their /// original values. /// </summary> /// <typeparam name='T'>Type of the object to be populated.</typeparam> /// <param name='toBePopulated'>The object to be populated</param> /// <param name='dataTable'>'name, 'value' Data table to populate the object from.</param> /// <param name='nameField'>Field name of the 'name' field'.</param> /// <param name='valueField'>Field name of the 'value' field.</param> /// <param name='options'>Setting to control conversions - e.g. nulls as empty strings.</param>  public static void PopulateFromNameValueDataTable<T>         (T toBePopulated, System.Data.DataTable dataTable, string nameField, string valueField, PopulateOptions options)     {         Type type = typeof(T);         bool nullStringsAsEmptyString = options == PopulateOptions.NullStringsAsEmptyString;          foreach (DataRow dataRow in dataTable.Rows)         {             string name = dataRow[nameField].ToString();             System.Reflection.PropertyInfo property = type.GetProperty(name);             object value = dataRow[valueField];              if (property != null)             {                 Type propertyType = property.PropertyType;                 if (nullStringsAsEmptyString && (propertyType == typeof(String)))                 {                     value = TypeHelper.EmptyStringIfNull(value);                 }                 else                 {                     value = TypeHelper.DefaultIfNull(value, propertyType);                 }                  property.SetValue(toBePopulated, System.Convert.ChangeType(value, propertyType), null);             }         }     } 

FURTHER EDIT: I am just in code, have an instance of Whotsit and I want to get the text string of the ‘TestProp’ property. It seems kind of weird I know, I can just use the literal ‘TestProp’ – or in the case of my class to datatable function I’d be in a foreach loop of PropertyInfos. I was just curious…

The original code had string constants, which I found clumsy.

Answer 1

No, there’s nothing to do this. The expression whotsit.TestProp will evaluate the property. What you want is the mythical ‘infoof’ operator:

// I wish... MemberInfo member = infoof(whotsit.TestProp); 

As it is, you can only use reflection to get the property by name – not from code. (Or get all the properties, of course. It still doesn’t help you with your sample though.)

One alternative is to use an expression tree:

Expression<Func<string>> = () => whotsit.TestProp; 

then examine the expression tree to get the property.

If none of this helps, perhaps you could tell us more about why you want this functionality?