Is there a C# equivalent of typeof for properties/methods/members?
No, unfortunately not. It's been discussed and even named: infoof
(pronounced "in-foof" for comedy value) but it's not been implemented... yet. Eric Lippert has a blog post about it.
The closest you can come in C# 3 is to make the compiler generate an expression tree, and then pull it out of that - but that's hardly pleasant.
I've just implemented an equivalent of constructions 'propertyof' 'methodof' 'fieldof' using Syste.Linq.Expressions
so instead of writing
var mi = typeof (string).GetMethod("Concat", new[] {typeof (object), typeof (object)});
you can use:
var mi = ReflectionHelper.MethodOf(() => string.Concat(new object(), new object()));
Why do we need this? because now we safe to refactor method, we use via reflection
listing of helper class (you may need to add some informative exceptions in methods):
/// <summary>
/// Represents a set of helpers for .net reflection
/// </summary>
public static class ReflectionHelper
{
#region Public methods
/// <summary>
/// Gets a MethodInfo object from specified expression
/// </summary>
/// <typeparam name="TResult"></typeparam>
/// <param name="methodExpression"></param>
/// <returns></returns>
public static MethodInfo MethodOf<TResult>(Expression<Func<TResult>> methodExpression)
{
return ((MethodCallExpression)methodExpression.Body).Method;
}
/// <summary>
/// Gets a MethodInfo object from specified expression
/// </summary>
/// <param name="methodExpression"></param>
/// <returns></returns>
public static MethodInfo MethodOf(Expression<Action> methodExpression)
{
return ((MethodCallExpression)methodExpression.Body).Method;
}
/// <summary>
/// Gets a MethodInfo object from specified expression
/// </summary>
/// <param name="methodExpression"></param>
/// <returns></returns>
public static MethodInfo MethodOf<TInstance, TResult>(Expression<Func<TInstance, TResult>> methodExpression)
{
return ((MethodCallExpression)methodExpression.Body).Method;
}
/// <summary>
/// Gets a MethodInfo object from specified expression
/// </summary>
/// <param name="methodExpression"></param>
/// <returns></returns>
public static MethodInfo MethodOf<TInstance>(Expression<Action<TInstance>> methodExpression)
{
return ((MethodCallExpression)methodExpression.Body).Method;
}
/// <summary>
/// Gets a PropertyInfo object from specified expression
/// </summary>
/// <param name="propertyGetExpression"></param>
/// <returns></returns>
public static PropertyInfo PropertyOf<TProperty>(Expression<Func<TProperty>> propertyGetExpression)
{
return ((MemberExpression)propertyGetExpression.Body).Member as PropertyInfo;
}
/// <summary>
/// Gets a PropertyInfo object from specified expression
/// </summary>
/// <param name="propertyGetExpression"></param>
/// <returns></returns>
public static PropertyInfo PropertyOf<TInstance, TProperty>(Expression<Func<TInstance, TProperty>> propertyGetExpression)
{
return ((MemberExpression)propertyGetExpression.Body).Member as PropertyInfo;
}
/// <summary>
/// Gets a FieldInfo object from specified expression
/// </summary>
/// <param name="fieldAccessExpression"></param>
/// <returns></returns>
public static FieldInfo FieldsOf<TProperty>(Expression<Func<TProperty>> fieldAccessExpression)
{
return ((MemberExpression)fieldAccessExpression.Body).Member as FieldInfo;
}
//TODO: ConstructorOf(...)
#endregion //Public methods
}
as I understand we could not use same aproach to getParameterInfo or EventInfo
Another approach to do that, described by Jb Evain, see: http://evain.net/blog/articles/2010/05/05/parameterof-propertyof-methodof?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+jbevain+%28Jb+in+a+nutshell%29
In c# 6 there's still no infoof
but there is nameof
:
var propertyInfo = typeof(MyClass).GetProperty(nameof(MyClass.MyProperty))
It's certainly not more terse, but at least it's refactoring friendly.