ParseOrDefault<T>

ParseOrDefault.cs

#region Fields

private static Dictionary<Type, MethodInfo> _tryParseMethods = new Dictionary<Type, MethodInfo>();

#endregion Fields

#region Methods

/// <summary>
/// Invokes a TryParse(string, out T) method on the given input.
/// If that invocation returns <c>false</c>, or the method does
/// not exist, then <c>default(T)</c> is returned.
/// </summary>
/// <typeparam name="T">Type to attempt to convert to</typeparam>
/// <param name="input">String to parse</param>
/// <returns>Parsed string, or <c>default(T)</c> if it can't be parsed.</returns>
public static T ParseOrDefault<T>(string input)
{
    // If T is actually Nullable<U>, then the type we want is U.  Otherwise, take T.
    Type t = typeof (T).IsGenericType && typeof(T).GetGenericTypeDefinition() == typeof (Nullable<>)
                    ? typeof (T).GetGenericArguments()[0]
                    : typeof (T);

    // If it's not cached, cache it.
    if (!_tryParseMethods.ContainsKey(t))
    {
        _tryParseMethods[t] = t.GetMethod("TryParse", new[] {typeof (string), t.MakeByRefType()});
    }

    // Now do the work.
    if (_tryParseMethods[t] != null)
    {
        object[] parameters = new object[] {input, null};
        bool parsed = (bool) _tryParseMethods[t].Invoke(null, parameters);
        if (parsed)
        {
            return (T) parameters[1];
        }
    }

    return default(T);
}

#endregion Methods