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Get name of property static as a string [duplicate]

I am getting into C# and I am having this issue:
namespace MyDataLayer
{
namespace Section1
{
public class MyClass
{
public class MyItem
{
public static string Property1{ get; set; }
}
public static MyItem GetItem()
{
MyItem theItem = new MyItem();
theItem.Property1 = "MyValue";
return theItem;
}
}
}
}
I have this code on a UserControl:
using MyDataLayer.Section1;
public class MyClass
{
protected void MyMethod
{
MyClass.MyItem oItem = new MyClass.MyItem();
oItem = MyClass.GetItem();
someLiteral.Text = oItem.Property1;
}
}
Everything works fine, except when I go to access Property1. The intellisense only gives me "Equals, GetHashCode, GetType, and ToString" as options. When I mouse over the oItem.Property1, Visual Studio gives me this explanation:
MemberMyDataLayer.Section1.MyClass.MyItem.Property1.getcannot be accessed with an instance reference, qualify it with a type name instead
I am unsure of what this means, I did some googling but wasn't able to figure it out.

In C#, unlike VB.NET and Java, you can't access static members with instance syntax. You should do:
MyClass.MyItem.Property1
to refer to that property or remove the static modifier from Property1 (which is what you probably want to do). For a conceptual idea about what static is, see my other answer.

You can only access static members using the name of the type.
Therefore, you need to either write,
MyClass.MyItem.Property1
Or (this is probably what you need to do) make Property1 an instance property by removing the static keyword from its definition.
Static properties are shared between all instances of their class, so that they only have one value. The way it's defined now, there is no point in making any instances of your MyItem class.

I had the same issue - although a few years later, some may find a few pointers helpful:
Do not use ‘static’ gratuitously!
Understand what ‘static’ implies in terms of both run-time and compile time semantics (behavior) and syntax.
A static entity will be automatically constructed some time before
its first use.
A static entity has one storage location allocated, and that is
shared by all who access that entity.
A static entity can only be accessed through its type name, not
through an instance of that type.
A static method does not have an implicit ‘this’ argument, as does an
instance method. (And therefore a static method has less execution
overhead – one reason to use them.)
Think about thread safety when using static entities.
Some details on static in MSDN:
Static Classes in C#
Static Constructors in C#

This causes the error:
MyClass aCoolObj = new MyClass();
aCoolObj.MyCoolStaticMethod();
This is the fix:
MyClass.MyCoolStaticMethod();
Explanation:
You can't call a static method from an instance of an object. The whole point of static methods is to not be tied to instances of objects, but instead to persist through all instances of that object, and/or to be used without any instances of the object.

No need to use static in this case as thoroughly explained. You might as well initialise your property without GetItem() method, example of both below:
namespace MyNamespace
{
using System;
public class MyType
{
public string MyProperty { get; set; } = new string();
public static string MyStatic { get; set; } = "I'm static";
}
}
Consuming:
using MyType;
public class Somewhere
{
public void Consuming(){
// through instance of your type
var myObject = new MyType();
var alpha = myObject.MyProperty;
// through your type
var beta = MyType.MyStatic;
}
}

cannot be accessed with an instance reference
It means you're calling a STATIC method and passing it an instance. The easiest solution is to remove Static, eg:
public static void ExportToExcel(IEnumerable data, string sheetName)
{

Remove the static in the function you are trying to call. This fixed the problem for me.

I got here googling for C# compiler error CS0176, through (duplicate) question Static member instance reference issue.
In my case, the error happened because I had a static method and an extension method with the same name. For that, see Static method and extension method with same name.
[May be this should have been a comment. Sorry that I don't have enough reputation yet.]

I know this is an old thread, but I just spent 3 hours trying to figure out what my issue was. I ordinarily know what this error means, but you can run into this in a more subtle way as well. My issue was my client class (the one calling a static method from an instance class) had a property of a different type but named the same as the static method. The error reported by the compiler was the same as reported here, but the issue was basically name collision.
For anyone else getting this error and none of the above helps, try fully qualifying your instance class with the namespace name. ..() so the compiler can see the exact name you mean.

Check whether your code contains a namespace which the right most part matches your static class name.
Given the a static Bar class, defined on namespace Foo, implementing a method Jump or a property, chances are you are receiving compiler error because there is also another namespace ending on Bar. Yep, fishi stuff ;-)
If that's so, it means your using a Using Bar; and a Bar.Jump() call, therefore one of the following solutions should fit your needs:
Fully qualify static class name with according namepace, which result on Foo.Bar.Jump() declaration. You will also need to remove Using Bar; statement
Rename namespace Bar by a diffente name.
In my case, the foollowing compiler error occurred on a EF (Entity Framework) repository project on an Database.SetInitializer() call:
Member 'Database.SetInitializer<MyDatabaseContext>(IDatabaseInitializer<MyDatabaseContext>)' cannot be accessed with an instance reference; qualify it with a type name instead MyProject.ORM
This error arouse when I added a MyProject.ORM.Database namespace, which sufix (Database), as you might noticed, matches Database.SetInitializer class name.
In this, since I have no control on EF's Database static class and I would also like to preserve my custom namespace, I decided fully qualify EF's Database static class with its namepace System.Data.Entity, which resulted on using the following command, which compilation succeed:
System.Data.Entity.Database.SetInitializer<MyDatabaseContext>(MyMigrationStrategy)
Hope it helps

YourClassName.YourStaticFieldName
For your static field would look like:
public class StaticExample
{
public static double Pi = 3.14;
}
From another class, you can access the staic field as follows:
class Program
{
static void Main(string[] args)
{
double radius = 6;
double areaOfCircle = 0;
areaOfCircle = StaticExample.Pi * radius * radius;
Console.WriteLine("Area = "+areaOfCircle);
Console.ReadKey();
}
}

The call is ambiguous between the following methods or properties (one static and one non-static)

Why am I not allowed to have a static and non-static methods with the same signature?
Let's say I have a class like this
public class TestClass
{
public object thing { get; set; }
public TestClass()
{
}
public TestClass(object thing)
{
this.thing = thing;
}
public static TestClass ConvertTestClass(object thing)
{
return new TestClass(thing);
}
public TestClass ConvertTestClass(object thing)
{
this.thing = thing;
return this;
}
}
and I try to use it like this
public class SomeOtherClass
{
public SomeOtherClass()
{
TestClass tc = TestClass.ConvertTestClass(new object());
TestClass tc2 = new TestClass();
tc2.ConvertTestClass(new object());
}
}
I get the following errors on TestClass.ConvertTestClass(new object());
The call is ambiguous between the following methods or properties: 'TestClass.ConvertTestClass(object)' and 'TestClass.ConvertTestClass(object)'
and these errors on tc2.ConvertTestClass(new object());
The call is ambiguous between the following methods or properties: 'TestClass.ConvertTestClass(object)' and 'TestClass.ConvertTestClass(object)'
Member 'TestClass.ConvertTestClass(object)' cannot be accessed with an instance reference; qualify it with a type name instead
Can the compiler really not tell the difference between the static and non static versions of that method or am I missing something here?
I am not using ReSharper (which seemed to be the root of a similar problem in other questions).

Its giving you an error, so its a safe bet that the compiler can't, or won't, discern between the two methods.
Its probably a bad idea to do this kind of overload anyways, as it's unclear which method you are intending to invoke, but if that isn't enough, the C# 5 specification defines a method signature like this (Section 3.6):
The signature of a method consists of the name of the method, the
number of type parameters and the type and kind (value, reference, or
output) of each of its formal parameters, considered in the order left
to right. For these purposes, any type parameter of the method that
occurs in the type of a formal parameter is identified not by its
name, but by its ordinal position in the type argument list of the
method. The signature of a method specifically does not include the
return type, the params modifier that may be specified for the
right-most parameter, nor the optional type parameter constraints.
It doesn't explicitly mention static, but it also doesn't include it as part of the definition of a "signature". Thus, its fair to assume that by the spec, a method overload cannot differ only in the fact that it is static or instanced.

I'd write this as a comment however it's easier to make this point in a proper editor.
I think you're only thinking about the logic of calling methods on the class externally i.e. from another class. Within the class methods with the same signature only differing by static doesn't make any sense. e.g you have a class with two methods as follows
public class MyClass
{
public static void HellowWorld()
{
Console.WriteLine("Hello World!");
}
public void HellowWorld()
{
Console.WriteLine("Howdy World!");
}
public void Greet()
{
HellowWorld();
}
}
When compiling you'll see as long as one of the methods is commented out it compiles without errors. You should be able to alternate the commented out method and compile the class succesfully. Indicating there's no way of differentiating which method should be called within the scope of the class.
You could argue that within the class you should be forced to use the same syntax to call a static method as you do externally e.g.
MyClass.HelloWorld();
However, this would defy scoping logic used throughout C#, why should you need to specify the class name within a class? I think such a change would also create ambiguity where the was none, and to do so now would of course break a lot of code out there.
I think the compiler logic as it is makes perfect sense.

How to trigger a static constructor

code:
class Base<T,U> where T:Base<T,U>,new() where U :class
{
protected static U _val = null;
internal static void ShowValue()
{
if(_val == null)new T(); //Without this line, it won't work as expected
Console.WriteLine (_val);
}
internal static void Virtual()
{
Console.WriteLine ("Base");
}
}
class Deriv :Base<Deriv,string>
{
static Deriv()
{
_val = "some string value";
}
internal static new void Virtual ()
{
Console.WriteLine ("Deriv");
}
}
public static void Main (string[] args)
{
Deriv.ShowValue();
Deriv.Virtual();
}
Thanks to the generics of .NET, I can create a bunch of specific classes reusing generic static methods defined in the generic base class. It can mimic inheritance polymorphism to some extent. But in order to initialize different version of static fields, I've to use static constructors. Unfortunately, we can't call them directly, therefore, we have to figure out a way to trigger it's invocation. The example given above showed a way. But I don't like either the instantiation,or the reflection approach. We also can't make a constraint on a static method of a generic parameter. So, I'd like to ask, if there is another way to do this kind of job!
Thanks beforehand!
~~~~~~~~~~~~~~~~
Some Conclusion (Maybe a little early):
It seems there is no workaround to deal with this kind of situation. I have to instantiate a subclass or use reflection. Considering the .cctors need merely be called once, I'm in favor of the reflection approach, because in some case, a new() constraint is just not a choice - like you're not supposed to expose the parameterless ctor to user.
After conducting further experiment, I find out that the .cctors may be called multi-times but only the first invocation will affect the setting of static fields. That's weird, but a good weirdness!
class MyClass
{
static int _val = 0;
static MyClass()
{
_val++;
Console.WriteLine (_val);
}
}
public static void Main (string[] args)
{
ConstructorInfo ci = typeof(MyClass).TypeInitializer;
ci.Invoke(new object[0]);
ci.Invoke(new object[0]);
ci.Invoke(new object[0]);
}
//result:
//1
//1
//1
//1

I would strongly advise you to rethink your design. Attempting to use this sort of workaround for "static inheritance" is fighting against some of the core designs of .NET.
It's unclear what bigger problem you're trying to solve, but trying "clever" code like this to simulate inheritance will lead to code which is very hard to maintain and diagnose in the longer term.
Without actually using a member of Deriv (or creating an instance of it), you basically won't trigger the static constructor. It's important to understand that Deriv.ShowValue() is basically converted into a call to
Base<Deriv, string>.ShowValue();
... so you're not actually calling anything on Deriv. Your calling code would actually be clearer if it were written that way.
EDIT: One other (clearly unfortunate) reason to avoid using type initializers explicitly is that there's a bug in .NET 4.5 which causes an exception to be thrown inappropriately in some cases. See my question on the topic for more information.

The correct solution is to invoke the type initializer (= static constructor) like this:
typeof(T).TypeInitializer.Invoke(null, null);
It needs both nulls. Specifying only one gives a MemberAccessException.
Thus, your code might want to look something like this:
internal static void ShowValue()
{
if (_val == null)
{
if (typeof(T).TypeInitializer != null)
typeof(T).TypeInitializer.Invoke(null, null);
if (_val == null)
throw new InvalidOperationException(string.Format("The type initializer of {0} did not initialize the _val field.", typeof(T)));
}
Console.WriteLine(_val);
}
And with that, you can remove the new() constraint.

You have no control of when the static constuctor will execute, but what is guaranteed is that it will run before accessing any static property or method and before instantiation.
There is really no reason to want the static constructor to execute at an earlier point. If you are not using anything from the class but you want the code in the static constructor to run, then something is wrong in your design.

Static constructors are automatically, only once. You cannot call them yourself.
An example from here:
public class Bus
{
// Static constructor:
static Bus()
{
System.Console.WriteLine("The static constructor invoked.");
}
public static void Drive()
{
System.Console.WriteLine("The Drive method invoked.");
}
}
class TestBus
{
static void Main()
{
Bus.Drive();
}
}
output:
The static constructor invoked.
The Drive method invoked.

I direct you to the MSDN article on Static Constructors and about 10% down the page:
A static constructor is called automatically to initialize the class
before the first instance is created or any static members are
referenced.

Is it possible to write a extension method for an abstract class

Why I'm unable to extend an abstract class. Is there any work around to achieve this?
In silverlight, Enum.GetNames is missing. So, I would like to extend it and have it in my utility assembly. By then, got into this.

The problem here is not that you can't add an extension method to an abstract class (you can - you can add an extension method to any type) - it's that you can't add a static method to a type with extension methods.
Extension methods are static methods that present themselves in C# as instance methods. But they're still static. Adding a static method to a type requires the ability to redefine the type, which you can only do if you have the source code :)
Best bet, if you want this method, is to write your own static and see if you can perhaps rip the code out of reflector.
However, it's entirely possible that it's not there because it's physically not supported in Silverlight (I don't know - I haven't investigate)
EDIT
Following on from your comment - and I hope that I've understood you here - I think what you want to be able to do is something like this (targetting object to prove the point):
public static class ExtraObjectStatics
{
public static void NewStaticMethod()
{
}
}
public class Test
{
public void foo()
{
//You can't do this - the static method doesn't reside in the type 'object'
object.NewStaticMethod();
//You can, of course, do this
ExtraObjectStatics.NewStaticMethod();
}
}
If you think about it - of course you can't inject new static methods into an existing type because, like I said in paragraph two, you have to be able to recompile the underlying type; and there simply is no way around that.
What you can do is (and I don't actually recommend this - but it's an option) create yourself a new type called Enum and place it inside a new namespace:
namespace MySystem
{
public class Enum
{
public static string[] GetNames()
{
//don't actually know how you're going to implement it :)
}
}
}
And now - when you want to use it, what you can't do is this:
using System;
using MySystem;
namespace MyCode
{
public class TestClass
{
public static void Test()
{
Enum.GetNames(); //error: ambiguous between System and MySystem
}
}
}
Because the using in the outermost scope to both 'System' and 'MySystem' will cause the compiler not to be able to resolve the correct Enum type.
What you can do, however, is this:
using System;
namespace MyCode
{
using MySystem; //move using to inside the namespace
public class TestClass
{
public static void Test()
{
//will now work, and will target the 'MySystem.Enum.GetNames()'
//method.
Enum.GetNames();
}
}
}
Now, code within that namespace (within that file only) will always resolve Enum to the one in your namespace because that's the nearest using directive in terms of scope.
So, you can think of this as overriding the whole Enum type for the benefit of a given namespace that includes a using MySystem; in it.
But, it does exactly that - it replaces the existing System.Enum with MySystem.Enum - meaning that you lose all the members of the System.Enum type.
You could get around this by writing wrapper methods in your Enum type around the System.Enum versions - making sure that you fully-qualify the type as System.Enum.
Having looked at the implementation of the GetNames method in Reflector - it relies on internal data that I don't think you're going to be able to build... but I would be very interested to hear if you are actually able to reproduce the method in Silverlight.

public abstract class Foo
{
public abstract void Bar();
}
public static class FooExtensions
{
// most useless extension method evar
public static void CallBar(this Foo me)
{
me.Bar();
}
}
Sure, no problem.

Detecting Interfaces in Generic Types

I have a method:
public void StoreUsingKey<T>(T value) where T : class, new() {
var idModel = value as IIDModel;
if (idModel != null)
Store<T>(idModel);
AddToCacheUsingKey(value);
}
that I would like to optionally call the following method, based on the value parameter's implementation of IIDModel.
public void Store<T>(T value) where T : class, IIDModel, new() {
AddModelToCache(value);
}
Is there a way to tell Store<T> that the value parameter from StoreUsingKey<T> implements IIDModel? Or am I going about this the wrong way?
Rich
Answer
Removing the new() constraint from each method allows the code to work. The problem was down to me trying to pass off an interface as an object which can be instantiated.

You already are. By putting the IIDModel constraint on the Store<T> method, you're guaranteeing, that the value parameter implements IIDModel.
Oh, ok I see what you're saying now. How about this:
public void StoreUsingKey<T>(T value) where T : class, new() {
if (idModel is IIDModel)
Store<T>((IIDModel)idModel);
AddToCacheUsingKey(value);
}
Edit yet again: Tinister is right. This by itself won't do the trick. However, if your Store method looks like what Joel Coehoorn posted, then it should work.

public void Store(IIDModel value) {
AddModelToCache(value);
}

Removing the new() constraint from each method allows the code to work. The problem was down to me trying to pass off an interface as an object which can be instantiated.