I have an object. Usually it is either long or string, so to simplify the code let's assume just that.
I have to create a method that tries to convert this object to a provided enum. So:
public object ToEnum(Type enumType, object value)
{
if(enumType.IsEnum)
{
if(Enum.IsDefined(enumType, value))
{
var val = Enum.Parse(enumType, (string)value);
return val;
}
}
return null;
}
With strings it works well. With numbers it causes problems, because a default underlying type for enum is int, not long and IsDefined throws an ArgumentException.
Of course I can do many checks, conversions or try-catches.
What I want is to have a clean and small code for that.
Any ideas how to make it readable and simple?
It feels to me like you only actually want to handle three cases:
Input is already the right type
Strings
Integers in various types
I believe this will do what you want for valid input:
public object ToEnum(Type enumType, object value)
{
if (value == null)
{
throw new ArgumentNullException("value");
}
if (enumType == null)
{
throw new ArgumentNullException("type");
}
if (!enumType.IsEnum)
{
return false;
}
string valueString = value as string;
if (valueString != null)
{
return Enum.IsDefined(enumType, value) ? Enum.Parse(enumType, valueString) : null;
}
if (value.GetType() == enumType)
{
return value;
}
// This appears to handle longs etc
return Enum.ToObject(enumType, value);
}
However, that will return a value of the right type even for undefined values. If you don't want that, change the last part to:
object candidate = Enum.ToObject(enumType, value);
return Enum.IsDefined(enumType, candidate) ? candidate : null;
Also, this will still throw an exception if you pass in a floating point number, or something like that. If you don't want that behaviour, you'll need to have a set of all the types you do want to accept, and check against that first.
Try this
public object ToEnum<T>(object value)
{
var type = typeof(T);
if (type.IsEnum)
{
int numberVal;
if (!int.TryParse(value.ToString(), out numberVal) && value.GetType() != typeof(string))
{
return null;
}
value = numberVal;
if (Enum.IsDefined(type, value))
{
T result = (T)Enum.Parse(type, value.ToString());
return result;
}
}
return null;
}
Related
I'm trying to write a "simple" Generic Get<T>; extension for
System.Runtime.MemoryCache.
Why "simple" ? Because generally I know object's real type before caching it, so when I retrieve it from cache, I'm not going to convert it in unpredictable ways.
For example: if boolean "true" value is stored in cache with cacheKey "id", so
Get<string>("id") == "true";
Get<int>("id") == 1; // any result > 0 is okay
Get<SomeUnpredictableType> == null; // just ignore these trouble conversions
Here's my incomplete implemention:
public static T DoGet<T>(this MemoryCache cache, string key) {
object value = cache.Get(key);
if (value == null) {
return default(T);
}
if (value is T) {
return (T)value;
}
// TODO: (I'm not sure if following logic is okay or not)
// 1. if T and value are both numeric type (e.g. long => double), how to code it?
// 2. if T is string, call something like Convert.ToString()
Type t = typeof(T);
t = (Nullable.GetUnderlyingType(t) ?? t);
if (typeof(IConvertible).IsAssignableFrom(value.GetType())) {
return (T)Convert.ChangeType(value, t);
}
return default(T);
}
Any suggestions are highly appreciated.
===================================
Update (04/11/2016):
For those nice suggestions given, I implement my first version of Get<T>
public class MemCache {
private class LazyObject<T> : Lazy<T> {
public LazyObject(Func<T> valueFactory) : base(valueFactory) { }
public LazyObject(Func<T> valueFactory, LazyThreadSafetyMode mode) : base(valueFactory, mode) { }
}
private static T CastValue<T>(object value) {
if (value == null || value is DBNull) {
return default(T);
}
Type valType = value.GetType();
if (valType.IsGenericType && valType.GetGenericTypeDefinition() == typeof(LazyObject<>)) {
return CastValue<T>(valType.GetProperty("Value").GetValue(value));
}
if (value is T) {
return (T)value;
}
Type t = typeof(T);
t = (Nullable.GetUnderlyingType(t) ?? t);
if (typeof(IConvertible).IsAssignableFrom(t) && typeof(IConvertible).IsAssignableFrom(value.GetType())) {
return (T)Convert.ChangeType(value, t);
}
return default(T);
}
private MemoryCache m_cache;
public T Get<T>(string key) {
return CastValue<T>(m_cache.Get(key));
}
public void Set<T>(string key, T value, CacheDependency dependency) {
m_cache.Set(key, value, dependency.AsCacheItemPolicy());
}
public T GetOrAdd<T>(string key, Func<T> fnValueFactory, CacheDependency dependency) {
LazyObject<T> noo = new LazyObject<T>(fnValueFactory, LazyThreadSafetyMode.ExecutionAndPublication);
LazyObject<T> old = m_cache.AddOrGetExisting(key, noo, dependency.AsCacheItemPolicy()) as LazyObject<T>;
try {
return CastValue<T>((old ?? noo).Value);
} catch {
m_cache.Remove(key);
throw;
}
}
/* Remove/Trim ... */
}
The essential work is to write a CastValue<T> to convert any object to desired type. And it doesn't have to handle very complicate condition because object types in cache is predictable for the programmer. And here's my version.
public static T CastValue<T>(object value) {
if (value == null || value is DBNull) {
return default(T);
}
if (value is T) {
return (T)value;
}
Type t = typeof(T);
t = (Nullable.GetUnderlyingType(t) ?? t);
if (typeof(IConvertible).IsAssignableFrom(t) && typeof(IConvertible).IsAssignableFrom(value.GetType())) {
return (T)Convert.ChangeType(value, t);
}
return default(T);
}
Proposal:
public static T DoGet<T>(this MemoryCache cache, string key)
{
object value = cache.Get(key);
if (value == null) {
return default(T);
}
// support for nullables. Do not waste performance with
// type conversions if it is not a nullable.
var underlyingType = Nullable.GetUnderlyingType(t);
if (underlyingType != null)
{
value = Convert.ChangeType(value, underlyingType);
}
return (T)value;
}
Usage (supposed you have an id of type int in the cache):
int id = Get<int>("id");
int? mayBeId = Get<int?>("id");
string idAsString = Get<int?>("id")?.ToString();
double idAsDouble = (double)Get<int>("id");
I haven't test it.
I'd like to know if there is a "safe" way to convert an object to an int, avoiding exceptions.
I'm looking for something like public static bool TryToInt32(object value, out int result);
I know I could make something like this:
public static bool TryToInt32(object value, out int result)
{
try
{
result = Convert.ToInt32(value);
return true;
}
catch
{
result = 0;
return false;
}
}
But I'd rather avoid exceptions, because they are slowing down the process.
I think this is more elegant, but it's still "cheap":
public static bool TryToInt32(object value, out int result)
{
if (value == null)
{
result = 0;
return false;
}
return int.TryParse(value.ToString(), out result);
}
Does anyone have better ideas?
UPDATE:
This sounds a little like splitting hairs, but converting an object to string forces the implementer to create a clear ToString() function. For example:
public class Percentage
{
public int Value { get; set; }
public override string ToString()
{
return string.Format("{0}%", Value);
}
}
Percentage p = new Percentage();
p.Value = 50;
int v;
if (int.TryParse(p.ToString(), out v))
{
}
This goes wrong, I can do two things here, or implement the IConvertable like this:
public static bool ToInt32(object value, out int result)
{
if (value == null)
{
result = 0;
return false;
}
if (value is IConvertible)
{
result = ((IConvertible)value).ToInt32(Thread.CurrentThread.CurrentCulture);
return true;
}
return int.TryParse(value.ToString(), out result);
}
But the ToInt32 method of the IConvertible cannot be canceled. So if it's not possible to convert the value, an exception cannot be avoided.
Or two: Is there a way to check if the object contains a implicit operator?
This is very poor:
if (value.GetType().GetMethods().FirstOrDefault(method => method.Name == "op_Implicit" && method.ReturnType == typeof(int)) != null)
{
result = (int)value;
return true;
}
int variable = 0;
int.TryParse(stringValue, out variable);
If it can't be parsed, the variable will be 0. See http://msdn.microsoft.com/en-us/library/f02979c7.aspx
Spurring from the comments. The response is no. You can't do what Convert.ToInt32(object) does without having throwed exceptions. You can do something similar (and you already did it). The only thing I would optimize is the case of value already an int.
if (value is int)
return (int)value;
You can't do as Convert.ToInt32(object) because Convert.ToInt32(object) doesn't simply test if value is short, int, long, ushort, ... and then cast them. It checks if the value is IConvertible. If yes it uses the IConvertible.ToInt32. Sadly the interface IConvertible is quite poor: it doesn't have non-throwing methods (IConvertible.Try*)
While stupid (but perhaps not too much), someone could make for example a UnixDateTime struct: (UnixTime is the number of seconds from midnight 1970-01-01), where the IConvertible.ToInt32 returns this number of seconds, while the ToString() returns a formatted date. All the int.TryParse(value.ToString(), out parsed) would choke, while the Convert.ToInt32 would work flawlessly.
This version using a type converter would only convert to string as a last resort but also not throw an exception:
public static bool TryToInt32(object value, out int result)
{
if (value == null)
{
result = 0;
return false;
}
var typeConverter = System.ComponentModel.TypeDescriptor.GetConverter(value);
if (typeConverter != null && typeConverter.CanConvertTo(typeof(int)))
{
var convertTo = typeConverter.ConvertTo(value, typeof(int));
if (convertTo != null)
{
result = (int)convertTo;
return true;
}
}
return int.TryParse(value.ToString(), out result);
}
No need to re-invent the wheel here. use int.TryParse to achieve your goal. It returns a bool to show that value is parsed or not. and if parsed the result is saved in the output variable.
int result;
object a = 5;
if(int.TryParse(a.ToString(),out result))
{
Console.WriteLine("value is parsed"); //will print 5
}
object b = a5;
if(int.TryParse(b.ToString(),out result))
{
Console.WriteLine("value is parsed");
}
else
{
Console.WriteLine("input is not a valid integer"); //will print this
}
Return a nullable int. that way you know whether you parsed 0.
int? value = int.TryParse(stringValue, out int outValue)
? outValue
: default(int?);
I would use a mixture of what you are already doing;
Check if the object is null - return false and the value 0;
Attempt to convert directly - if successful, return true and the converted value
Attempt to parse value.ToString() - if successfull, return true and the parsed value
Any other case - Return false and the value 0, as object is not convertible/parsible
The resulting code:
public static bool TryToInt32(object value, out int result)
{
result = 0;
if (value == null)
{
return false;
}
//Try to convert directly
try
{
result = Convert.ToInt32(value);
return true;
}
catch
{
//Could not convert, moving on
}
//Try to parse string-representation
if (Int32.TryParse(value.ToString(), out result))
{
return true;
}
//If parsing also failed, object cannot be converted or paresed
return false;
}
I wrote this mess, looking at it makes me sad.
using System;
using System.Globalization;
internal static class ObjectExt
{
internal static bool TryConvertToDouble(object value, out double result)
{
if (value == null || value is bool)
{
result = 0;
return false;
}
if (value is double)
{
result = (double)value;
return true;
}
var text = value as string;
if (text != null)
{
return double.TryParse(text, NumberStyles.Float, CultureInfo.InvariantCulture, out result);
}
var convertible = value as IConvertible;
if (convertible == null)
{
result = 0;
return false;
}
try
{
result = convertible.ToDouble(CultureInfo.InvariantCulture);
return true;
}
catch (Exception)
{
result = 0;
return false;
}
}
}
Edit
Notice now I answered for double when the question was int, keeping it any way. Maybe useful for someone.
This is how I like to do it:
object v = someValue;
if (int.TryParse($"{v}", out var extractedValue))
{
// do something with extractedValue
}
I am trying t get this working but somehow its going out of my hand... I want to be able to check null or empty to whatever type i assigned.
EX:
int i =0;
string mystring = "";
var reult = CheckNullOrEmpty(10) // passing int
var result 1 = CheckNullOrEmpty(mystring) // passing string
public bool CheckNullOrEmpty<T>(T value)
{
// check for null or empty for strings
// check for null i.e. 0 for int
}
can someone help me with this.. I am trying to understand how generics works for this simple method.
public static bool CheckNullOrEmpty<T>(T value)
{
if (typeof(T) == typeof(string))
return string.IsNullOrEmpty(value as string);
return value == null || value.Equals(default(T));
}
How to use:
class Stub { }
bool f1 = CheckNullOrEmpty(""); //true
bool f2 = CheckNullOrEmpty<string>(null); //true
bool f3 = CheckNullOrEmpty(0); //true
bool f4 = CheckNullOrEmpty<Stub>(null); //true
You can check against default(T);
public bool CheckNullOrEmpty<T>(T value)
{
return value == default(T);
}
For more informations: http://msdn.microsoft.com/en-us/library/xwth0h0d.aspx
You can use default() -
e.g.:
if(value != default(T))
from MSDN:
Given a variable t of a parameterized type T, the statement t = null
is only valid if T is a reference type and t = 0 will only work for
numeric value types but not for structs. The solution is to use the
default keyword, which will return null for reference types and zero
for numeric value types. For structs, it will return each member of
the struct initialized to zero or null depending on whether they are
value or reference types.
http://msdn.microsoft.com/en-us/library/xwth0h0d(v=vs.80).aspx
Because your CheckNullOrEmpty implementation differs by type, you can't have that check as a generic function.
If you use Nullable value types however, you can use GetValueOrDefault():
int? i = 0;
var result = i.GetValueOrDefault(10);
Then for string, just have an extension method:
public static string GetValueOrDefault(this string item, string defaultValue = "")
{
return !string.IsNullOrWhiteSpace(item) ? item : defaultValue;
}
Then you can do:
string i = null;
string mystring = "";
var result = i.GetValueOrDefault(mystring);
I've added a couple of re-factorings:
1. DBNull is not seen as isnullorempty so added the (value as string)
2. Passing a datatable row[column] that was created dynamically at runtime (like: row["PropertyName"]) will not see this as a string with typeof(T) due to the fact that the column type base is object. So added an extra check for typeof(object) and if not null test that the ToString() is empty value. I haven't tested this fully so may not work for all types of data columns.
public static bool CheckNullOrEmpty<T>(T value)
{
// note: this does not see DBNull as isnullorempty.
if (typeof(T) == typeof(string))
{
if (!string.IsNullOrEmpty(value as string))
{
return string.IsNullOrEmpty(value.ToString().Trim());
}
else
{
return true;
}
}
else if (typeof(T) == typeof(object))
{
// note: datatable columns are always seen as object at runtime with generic T regardless of how they are dynamically typed?
if (value != null) {
return string.IsNullOrEmpty(value.ToString().Trim());
}
}
return value == null || value.Equals(default(T));
}
I'm trying to find a way to check and see if the value of a given object is equal to its default value. I've looked around and come up with this:
public static bool IsNullOrDefault<T>(T argument)
{
if (argument is ValueType || argument != null)
{
return object.Equals(argument, default(T));
}
return true;
}
The problem I'm having is that I want to call it like this:
object o = 0;
bool b = Utility.Utility.IsNullOrDefault(o);
Yes o is an object, but I want to make it figure out the base type and check the default value of that. The base type, in this case, is an integer and I want to know in this case if the value is equal to default(int), not default(object).
I'm starting to think this might not be possible.
In your example, your integer is boxed and therefore your T is going to be object, and the default of object is null, so that's not valuable to you. If the object is a value type, you could get an instance of it (which would be the default) to use as a comparison. Something like:
if (argument is ValueType)
{
object obj = Activator.CreateInstance(argument.GetType());
return obj.Equals(argument);
}
You'd want to deal with other possibilities before resorting to this. Marc Gravell's answer brings up some good points to consider, but for a full version of your method, you might have
public static bool IsNullOrDefault<T>(T argument)
{
// deal with normal scenarios
if (argument == null) return true;
if (object.Equals(argument, default(T))) return true;
// deal with non-null nullables
Type methodType = typeof(T);
if (Nullable.GetUnderlyingType(methodType) != null) return false;
// deal with boxed value types
Type argumentType = argument.GetType();
if (argumentType.IsValueType && argumentType != methodType)
{
object obj = Activator.CreateInstance(argument.GetType());
return obj.Equals(argument);
}
return false;
}
if o is null, in a non-generic (object) method, you will have no access to the original type - and you can't do much about that.
Hence, the only time it matters is non-nullable value-types, so:
Type type = value.GetType();
if(!type.IsValueType) return false; // can't be, as would be null
if(Nullable.GetUnderlyingType(type) != null) return false; // ditto, Nullable<T>
object defaultValue = Activator.CreateInstance(type); // must exist for structs
return value.Equals(defaultValue);
Converted Anthony Pegram's Answer into an extension method:
using System;
//Adapted from https://stackoverflow.com/a/6553276/1889720
public static class ObjectExtensions
{
public static bool IsNullOrDefault<TObject>(this TObject argument)
{
// deal with normal scenarios
if (argument == null)
{
return true;
}
if (object.Equals(argument, default(TObject)))
{
return true;
}
// deal with non-null nullables
Type methodType = typeof(TObject);
if (Nullable.GetUnderlyingType(methodType) != null)
{
return false;
}
// deal with boxed value types
Type argumentType = argument.GetType();
if (argumentType.IsValueType && argumentType != methodType)
{
object obj = Activator.CreateInstance(argument.GetType());
return obj.Equals(argument);
}
return false;
}
}
Usage syntax:
myVariable.IsNullOrDefault();
Expanding on Marc Gravell's answer, by getting the run-time type as an argument:
// Handles boxed value types
public static bool IsNullOrDefault([CanBeNull] this object #object,
[NotNull] Type runtimeType)
{
if (#object == null) return true;
if (runtimeType == null) throw new ArgumentNullException("runtimeType");
// Handle non-null reference types.
if (!runtimeType.IsValueType) return false;
// Nullable, but not null
if (Nullable.GetUnderlyingType(runtimeType) != null) return false;
// Use CreateInstance as the most reliable way to get default value for a value type
object defaultValue = Activator.CreateInstance(runtimeType);
return defaultValue.Equals(#object);
}
For those of you that will challenge my use case, I want to list the values of properties on an arbitrary object, omitting properties which set to their defaults (for a more concise display).
Because propertyInfo.GetValue(targetObject, null) returns an object, and value types are boxed, I cannot use a generic method. By passing propertyInfo.PropertyType as the second parameter to this method I can avoid the problem a generic method has with boxed value types.
The following will sort it out.
public static bool IsNullOrDefault<T>(T argument)
{
if (argument is ValueType || argument != null)
{
return object.Equals(argument, GetDefault(argument.GetType()));
}
return true;
}
public static object GetDefault(Type type)
{
if(type.IsValueType)
{
return Activator.CreateInstance(type);
}
return null;
}
Make an extension method
public static class DateExtension
{
public static bool IsNullOrDefault(this DateTime? value)
{
return default(DateTime) == value || default(DateTime?) == value;
}
}
Solution with linq expressions. First call for type will be relatively slow, but then it should work just as quick as usual code.
public static class DefaultHelper
{
private delegate bool IsDefaultValueDelegate(object value);
private static readonly ConcurrentDictionary<Type, IsDefaultValueDelegate> Delegates
= new ConcurrentDictionary<Type, IsDefaultValueDelegate>();
public static bool IsDefaultValue(this object value)
{
var type = value.GetType();
var isDefaultDelegate = Delegates.GetOrAdd(type, CreateDelegate);
return isDefaultDelegate(value);
}
private static IsDefaultValueDelegate CreateDelegate(Type type)
{
var parameter = Expression.Parameter(typeof(object));
var expression = Expression.Equal(
Expression.Convert(parameter, type),
Expression.Default(type));
return Expression.Lambda<IsDefaultValueDelegate>(expression, parameter).Compile();
}
}
I am trying to combine a bunch of similar methods into a generic method. I have several methods that return the value of a querystring, or null if that querystring does not exist or is not in the correct format. This would be easy enough if all the types were natively nullable, but I have to use the nullable generic type for integers and dates.
Here's what I have now. However, it will pass back a 0 if a numeric value is invalid, and that unfortunately is a valid value in my scenarios. Can somebody help me out? Thanks!
public static T GetQueryString<T>(string key) where T : IConvertible
{
T result = default(T);
if (String.IsNullOrEmpty(HttpContext.Current.Request.QueryString[key]) == false)
{
string value = HttpContext.Current.Request.QueryString[key];
try
{
result = (T)Convert.ChangeType(value, typeof(T));
}
catch
{
//Could not convert. Pass back default value...
result = default(T);
}
}
return result;
}
What if you specified the default value to return, instead of using default(T)?
public static T GetQueryString<T>(string key, T defaultValue) {...}
It makes calling it easier too:
var intValue = GetQueryString("intParm", Int32.MinValue);
var strValue = GetQueryString("strParm", "");
var dtmValue = GetQueryString("dtmPatm", DateTime.Now); // eg use today's date if not specified
The downside being you need magic values to denote invalid/missing querystring values.
I know, I know, but...
public static bool TryGetQueryString<T>(string key, out T queryString)
What about this? Change the return type from T to Nullable<T>
public static Nullable<T> GetQueryString<T>(string key) where T : struct, IConvertible
{
T result = default(T);
if (String.IsNullOrEmpty(HttpContext.Current.Request.QueryString[key]) == false)
{
string value = HttpContext.Current.Request.QueryString[key];
try
{
result = (T)Convert.ChangeType(value, typeof(T));
}
catch
{
//Could not convert. Pass back default value...
result = default(T);
}
}
return result;
}
Convert.ChangeType() doesn't correctly handle nullable types or enumerations in .NET 2.0 BCL (I think it's fixed for BCL 4.0 though). Rather than make the outer implementation more complex, make the converter do more work for you. Here's an implementation I use:
public static class Converter
{
public static T ConvertTo<T>(object value)
{
return ConvertTo(value, default(T));
}
public static T ConvertTo<T>(object value, T defaultValue)
{
if (value == DBNull.Value)
{
return defaultValue;
}
return (T) ChangeType(value, typeof(T));
}
public static object ChangeType(object value, Type conversionType)
{
if (conversionType == null)
{
throw new ArgumentNullException("conversionType");
}
// if it's not a nullable type, just pass through the parameters to Convert.ChangeType
if (conversionType.IsGenericType && conversionType.GetGenericTypeDefinition().Equals(typeof(Nullable<>)))
{
// null input returns null output regardless of base type
if (value == null)
{
return null;
}
// it's a nullable type, and not null, which means it can be converted to its underlying type,
// so overwrite the passed-in conversion type with this underlying type
conversionType = Nullable.GetUnderlyingType(conversionType);
}
else if (conversionType.IsEnum)
{
// strings require Parse method
if (value is string)
{
return Enum.Parse(conversionType, (string) value);
}
// primitive types can be instantiated using ToObject
else if (value is int || value is uint || value is short || value is ushort ||
value is byte || value is sbyte || value is long || value is ulong)
{
return Enum.ToObject(conversionType, value);
}
else
{
throw new ArgumentException(String.Format("Value cannot be converted to {0} - current type is " +
"not supported for enum conversions.", conversionType.FullName));
}
}
return Convert.ChangeType(value, conversionType);
}
}
Then your implementation of GetQueryString<T> can be:
public static T GetQueryString<T>(string key)
{
T result = default(T);
string value = HttpContext.Current.Request.QueryString[key];
if (!String.IsNullOrEmpty(value))
{
try
{
result = Converter.ConvertTo<T>(value);
}
catch
{
//Could not convert. Pass back default value...
result = default(T);
}
}
return result;
}
You can use sort of Maybe monad (though I'd prefer Jay's answer)
public class Maybe<T>
{
private readonly T _value;
public Maybe(T value)
{
_value = value;
IsNothing = false;
}
public Maybe()
{
IsNothing = true;
}
public bool IsNothing { get; private set; }
public T Value
{
get
{
if (IsNothing)
{
throw new InvalidOperationException("Value doesn't exist");
}
return _value;
}
}
public override bool Equals(object other)
{
if (IsNothing)
{
return (other == null);
}
if (other == null)
{
return false;
}
return _value.Equals(other);
}
public override int GetHashCode()
{
if (IsNothing)
{
return 0;
}
return _value.GetHashCode();
}
public override string ToString()
{
if (IsNothing)
{
return "";
}
return _value.ToString();
}
public static implicit operator Maybe<T>(T value)
{
return new Maybe<T>(value);
}
public static explicit operator T(Maybe<T> value)
{
return value.Value;
}
}
Your method would look like:
public static Maybe<T> GetQueryString<T>(string key) where T : IConvertible
{
if (String.IsNullOrEmpty(HttpContext.Current.Request.QueryString[key]) == false)
{
string value = HttpContext.Current.Request.QueryString[key];
try
{
return (T)Convert.ChangeType(value, typeof(T));
}
catch
{
//Could not convert. Pass back default value...
return new Maybe<T>();
}
}
return new Maybe<T>();
}
I like to start with a class like this
class settings
{
public int X {get;set;}
public string Y { get; set; }
// repeat as necessary
public settings()
{
this.X = defaultForX;
this.Y = defaultForY;
// repeat ...
}
public void Parse(Uri uri)
{
// parse values from query string.
// if you need to distinguish from default vs. specified, add an appropriate property
}
This has worked well on 100's of projects. You can use one of the many other parsing solutions to parse values.