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CS0051 Inconsistent accessibility: parameter type 'CharityDbContext' is less accessible than method 'Campaign.Campaign(CharityDbContext)' [duplicate]

I'm trying to pass an object (a reference to the currently logged on user, basically) between two forms. At the moment, I have something along these lines in the login form:
private ACTInterface oActInterface;
public void button1_Click(object sender, EventArgs e)
{
oActInterface = new ACTInterface(#"\\actserver\Database\Premier.pad",this.textUser.Text,this.textPass.Text);
if (oActInterface.checkLoggedIn())
{
//user has authed against ACT, so we can carry on
clients oClientForm = new clients(oActInterface);
this.Hide();
oClientForm.Show();
}
else...
on the next form (clients), I have:
public partial class clients : Form
{
private ACTInterface oActInt {get; set;}
public clients(ACTInterface _oActInt)
...which results in me getting:
Error 1 Inconsistent accessibility:
parameter type 'support.ACTInterface' is less accessible than method
'support.clients.clients(support.ACTInterface)'
c:\work\net\backup\support\support\clients.cs 20 16 support
I don't really understand what the problem is - both fields are private, and accessed by the relevant public method from the form. Googling doesn't really help, as it just points towards one element being public and the other private, which isn't the case here.
Anybody help?

Constructor of public class clients is public but it has a parameter of type ACTInterface that is private (it is nested in a class?). You can't do that. You need to make ACTInterface at least as accessible as clients.

Make the class public.
class NewClass
{
}
is the same as:
internal class NewClass
{
}
so the class has to be public

If sounds like the type ACTInterface is not public, but is using the default accessibility of either internal (if it is top-level) or private (if it is nested in another type).
Giving the type the public modifier would fix it.
Another approach is to make both the type and the method internal, if that is your intent.
The issue is not the accessibility of the field (oActInterface), but rather of the type ACTInterface itself.

What is the accessibility of the type support.ACTInterface. The error suggests it is not public.
You cannot expose a public method signature where some of the parameter types of the signature are not public. It wouldn't be possible to call the method from outside since the caller couldn't construct the parameters required.
If you make support.ACTInterface public that will remove this error. Alternatively reduce the accessibility of the form method if possible.

parameter type 'support.ACTInterface' is less accessible than method
'support.clients.clients(support.ACTInterface)'
The error says 'support.ACTInterface' is less accessible because you have made the interface as private, at least make it internal or make it public.

The problem doesn't seem to be with the variable but rather with the declaration of ACTInterface. Is ACTInterface declared as internal by any chance?

When I received this error, I had a "helper" class that I did not declare as public that caused this issue inside of the class that used the "helper" class. Making the "helper" class public solved this error, as in:
public ServiceClass
{
public ServiceClass(HelperClass _helper)
{ }
}
public class HelperClass {} // Note the public HelperClass that solved my issue.
This may help someone else who encounters this.

You can get Parameter (class that have less accessibility) as object then convert it to your class by as keyword.

In my case I hadone class in a file and I was passing a instance of that class to the constructor of my form in another file.
The problem was had declared the class without the public modifier : class MyClass {}
I could have solved it by changing it to public class MyClass {}

If this error occurs when you want to use a classvariable in a new form, you should put the class definition in the
Formname.Designer.cs
instead of the Formname.cs file.

After updating my entity framework model, I found this error infecting several files in my solution. I simply right clicked on my .edmx file and my TT file and click "Run Custom Tool" and that had me right again after a restart of Visual Studio 2012.

All the answers that say make the type ActInterface as public are right. I am only putting this post to explicitly mention why that's an issue
If a parameter to your public class constructor is private or internal qualified class, it means you wont be able to create an object of that parameter class from outside of the assembly and when you cannot instantiate the parameter object, how can you call this constructor to instantiate an object of this class ?

Try making your constructor private like this:
private Foo newClass = new Foo();

Cannot access internal classes outside of DLL & certain public variables aren't accessible

I'm having a hard time making this work.
The 3 classes FooType, WebApp & IWebApp must not be accessbile \ visible outside of this DLL. So hence the sealed & internal classes.
Issues I'm having are ...
1) In WebApp class, FeeType1 is not accessible in RouteOneBuilder method's parameter.
2) In WebApp class, FeeType1 is not accessible \ visible in switch's case-statement. (need to be visible).
3) In WebApp class, CreditApplication of FeeType1 property is not visible in the switch's case-statement (need to be visible).
Is there a better way to this complicated script? Am I already screwed for exposing classes outside of this DLL? Can all of step 1 to 4 be resolved differently (or be fixed somehow)?
I don't see how can I make this any simplier.
internal static class FooType
{
public class FeeType
{
public FeeType() { }
public string CreditApplication = "Credit Application";
public string CreditVehicle = "Credit Vehicle";
}
public FeeType FeeType1
{
get { return new FeeType(); }
private set { }
}
}
sealed class WebApp : IWebApp
{
public string RouteOneBuilder(FooType.FeeType1 typing)
{
var xml = "";
switch(typing)
{
case FooType.FeeType1.CreditApplication:
xml = "asdf";
break;
default:
throw new Exception("Unknown value");
}
return xml;
}
}
internal interface IWebApp
{
string RouteOneBuilder(FooType.FeeType typing);
}

Your definition of a sealed class is incorrect. It is not an access modifier like public, private, protected and internal. Marking a class sealed only says that it cannot be inherited from; it does not say anything about access per se.
From the MSDN documentation:
When applied to a class, the sealed modifier prevents other classes
from inheriting from it.
That means that you can still provide a public class that is sealed. However, if you try to inherit from a sealed class, you will receive a compiler error like this:
cannot derive from sealed type 'YourNamespace.YourSealedClass'.
Also, I suggest you read this and this regarding internal/public and nested classes.
Now, looking at the code you provided, the following compiler errors pop up:
FooType.FeeType1': cannot declare instance members in a static class
This error means that if the class is declared static, all of the members must be static too.
FooType.FeeType1' is a 'property' but is used like a 'type'
This arises from the fact that the class is static but none of the members are.
Inconsistent accessibility: parameter type 'FooType.FeeType' is less
accessible than method 'IWebApp.RouteOneBuilder(FooType.FeeType)'
The return type and each of the types referenced in the formal parameter list of a method must be at least as accessible as the method itself.
You can find more information about the last error here.

The design is not correct.
If a type is marked as internal this indicates that it should never be accessed outside of its DLL. If this type must be accessed outside of the DLL in which it is declared, it should not be marked internal.
What constraint is preventing you from using a public modifier or from including the types in the same DLL as the consuming code?
In certain cases it is useful for external DLLs or EXEs to view internal members declared in another DLL. One notable case is for unit testing. The code under test may have an internal access modifier, but your test DLL still needs to access the code in order to test it. You can add the following to AssemblyInfo.cs of the project containing the internal members to allow external access.
[assembly:InternalsVisibleTo("Friend1a")]
See InternalsVisibleToAttribute Class for more details.
Side note: The sealed access modifier doesn't prevent access from outside of the declaring DLL. It prevents other types from extending the type.

UserControl with generic control - broken in designer

I have a WinForm-UserControl with a generic type for a control. To create the instance, I changed the Designer code:
public class TimeBarForm<T> : where T : TimeBarPanel
{
protected void InitializeComponent()
{
// ...
this.m_timeBarPanel = (T)Activator.CreateInstance(typeof(T));
// ...
}
}
This works fine at compile time but on design time it's broken. On the TimeBarForm:
Failed to parse method 'InitializeComponent'. The parser reported the following error
'Type parameters are not suppported Parameter name: typeSymbol'.
Please look in the Task List for potential errors.
The derived classes just show the default designer for an empty user control.
I also tried to pass the type in the constructor but VS complains that I should not touch autogenerated code (It dosn't like the if-conditions). I want a generic UserControl where I can decide about the specialization of an abstract class/control in a derived type and I should still be able to use the designer in the base class. I'm open to other suggestions to solve this as this might not be the best solution. I'm not very used to UserControl-design.
VS 2015/ .Net 4.6

I've done a somewhat dirty workaround but I can use the designer for the base and derived classes. I removed the generic and replaced the Activator-class with a call to the constructor. When I'm done with designing the base class I coment this line. The derived classes call the constructor to pass the instance:
public TimeBarForm(TimeBarPanel timeBarPanel)
{
this.m_timeBarPanel = timeBarPanel;
InitializeComponent();
}
To make the designer for the derived classes happy, a second constructor provides a default instance:
public TimeBarForm()
{
this.m_timeBarPanel = new TimeBarPanel();
InitializeComponent();
}
Not pretty but I can live with it.

Passing List between C# Forms

I am trying to learn passing a list between two C# forms using constructors as shown below. On the first form I did:
List<Cat> myCatList;
//list populating function...
private void btnDisplay_Click(object sender, EventArgs e)
{
df = new DisplayForm(myCatList);
df.Show();
this.Hide();
}
On the next form, I tried to receive the data as shown below:
List<Cat> catList;
public DisplayForm(List<Cat> catList)
{
InitializeComponent();
this.catList = catList;
}
But I always get an error on the second form constructor saying:
Error 1 Inconsistent accessibility: parameter type 'System.Collections.Generic.List<_05_WindowsFormsAppCat.Cat>' is less accessible than method '_05_WindowsFormsAppCat.DisplayForm.DisplayForm(System.Collections.Generic.List<_05_WindowsFormsAppCat.Cat>)'
Any ideas?

The List part is a complete red herring here. You'd get exactly the same problem if your constructor had a Cat parameter instead of a List<Cat> parameter.
Your Cat type is probably internal, because you haven't declared it as public. Therefore you can't use it in the signature of a public member such as this:
public DisplayForm(List<Cat> catList)
Options:
Make Cat a public class
Make your DisplayForm constructor internal
Personally I'm all for keeping things as private as is practical - although for small projects it won't make much difference, particularly for apps which are just a single assembly anyway. Most developers tend to err on the side of making everything public, which is a mistake IMO, but it's a judgement call. Both of the above options will work fine... but you should at least think about whether you want any other assembly to know about the Cat type (or indeed whether you want code in other assemblies to be able to call that constructor).

Where did you declare the Cat class? It must be publicly accessible to the DisplayForm class. You may have to add the public keyword to its declaration.
This is known as the accessibility of a type or a member.
Here is a reference of the different levels and their default values:
http://msdn.microsoft.com/en-us/library/ba0a1yw2.aspx
I'm guessing that your Cat type was either in another assembly (project) as your DisplayForm, in which case it was by default not visible to classes in that project, or that you defined it as a nested class of your first Form class which would have made it private and accessible in the scope of that Form.

How to handle static fields that vary by implementing class

I hit this problem all the time. Suppose I am making a command line interface (Java or C#, the problem is the same I think, I will show C# here).
I define an interface ICommand
I create an abstract base class CommandBase which implements ICommand, to contain common code.
I create several implementation classes, each extending the base class (and by extension the interface).
Now - suppose that the interface specifies that all commands implement the Name property and the Execute method...
For Name each of my instance classes must return a string that is the name of that command. That string ("HELP", "PRINT" etc) is static to the class concerned. What I would love to be able to do is define:
public abstract static const string Name;
However (sadly) you cannot define static members in an interface.
I have struggled with this issue for years now (pretty much any place I have a family of similar classes) and so will post my own 3 possible solutions below for your votes. However since none of them is ideal I am hoping someone will post a more elegant solution.
UPDATE:
I can't get the code formatting to work properly (Safari/Mac?). Apologies.
The example I am using is trivial. In real life there are sometimes dozens of implementing classes and several fields of this semi-static type (ie static to the implementing class).
I forgot to mention - ideally I want to be able to query this information statically:
string name = CommandHelp.Name;
2 of my 3 proposed solutions require that the class be instantiated before you can find out this static information which is ugly.

You may consider to use attributes instead of fields.
[Command("HELP")]
class HelpCommand : ICommand
{
}

As you mentioned, there is no way to enforce this from the interface level. Since you are using an abstract class, however, what you can do is declare the property as abstract in the base class which will force the inheriting class it override it. In C#, that would look like this:
public abstract class MyBaseClass
{
public abstract string Name { get; protected set; }
}
public class MyClass : MyBaseClass
{
public override string Name
{
get { return "CommandName"; }
protected set { }
}
}
(Note that the protected set prevents outside code changing the name.)
This may not be exactly what you're looking for, but it's as close as I think you can get. By definition, static fields do not vary; you simply can't have a member that is both static and overridable for a given class.

public interface ICommand {
String getName();
}
public class RealCommand implements ICommand {
public String getName() {
return "name";
}
}
Simple as that. Why bother having a static field?
Obs.: Do not use a field in an abstract class that should be initiated in a subclass (like David B suggestion). What if someone extends the abstract class and forget to initiate the field?

just add the name property to the base class and pass it ito the base class's constructor and have the constuctor from the derived class pass in it's command name

What I usually do (in pseudo):
abstract class:
private const string nameConstant = "ABSTRACT";
public string Name
{
get {return this.GetName();}
}
protected virtual string GetName()
{
return MyAbstractClass.nameConstant;
}
----
class ChildClass : MyAbstractClass
{
private const string nameConstant = "ChildClass";
protected override string GetName()
{
return ChildClass.nameConstant;
}
}
Of course, if this is a library that other developers will use, it wouldn't hurt if you add some reflection in the property to verify that the current instance in fact does implement the override or throw an exception "Not Implemented".

My answer will relate to Java, as that is what I know. Interfaces describe behavior, and not implementation. Additionally, static fields are tied to the classes, and not instances. If you declared the following:
interface A { abstract static NAME }
class B { NAME = "HELP" }
class C { NAME = "PRINT" }
Then how could this code know which NAME to link to:
void test(A a) {
a.NAME;
}
How I would suggest to implement this, is one of the following ways:
Class name convention, and the base class derives the name from the class name. If you wish to deviate from this, override the interface directly.
The base class has a constructor which takes name
Use annotations and enforce their presence through the base class.
However, a much better solution is proabably to use enums:
public enum Command {
HELP { execute() }, PRINT { execute() };
abstract void execute();
}
This is much cleaner, and allows you to use switch statements, and the NAME will be easily derived. You are however not able to extended the number of options runtime, but from your scenario description that might not be even needed.

[Suggested answer # 3 of 3]
I have not tried this yet and it would not be so nice in Java (I think?) but I could just tag my classes with Attributes:
[CammandAttribute(Name="HELP")]
Then I can use reflection to get that static information. Would need some simple helper methods to make the information easily available to the clients of the class but this could go in the base class.

From a design perspective, I think it is wrong to require a static implementation member... The relative deference between performance and memory usage between static and not for the example string is minimal. That aside, I understand that in implementation the object in question could have a significantly larger foot print...
The essential problem is that by trying to setup a model to support static implementation members that are avaialble at a base or interface level with C# is that our options are limited... Only properties and methods are available at the interface level.
The next design challenge is whether the code will be base or implementation specific. With implementation your model will get some valdiation at compile time at the code of having to include similar logic in all implementations. With base your valdiation will occur at run time but logic would be centralized in one place. Unfortunately, the given example is the perfect show case for implemntation specific code as there is no logic associated with the data.
So for sake of the example, lets assume there is some actual logic associated with the data and that it is extensive nad/or complex enough to provide a showcase for base classing. Setting aside whether the base class logic uses any impelementation details or not, we have the problem of insuring implemtation static initialization. I would recommend using an protected abstract in the base class to force all implementations to created the needed static data that would be valdated at compile time. All IDE's I work with make this very quick any easy. For Visual Studio it only takes a few mouse clicks and then just changing the return value essentially.
Circling back to the very specific nature of the question and ignoring many of the other design problems... If you really must keep this entire to the nature of static data and still enforce it thru the nature confines of the problem... Definately go with a method over properties, as there are way to many side effects to make go use of properties. Use a static member on the base class and use a static constructor on the implementations to set the name. Now keep in mind that you have to valdiate the name at run-time and not compile time. Basically the GetName method on the base class needs to handle what happens when an implementation does not set it's name. It could throw an exception making it brutally apparent that something is worng with an implementation that was hopefulyl cause by testing/QA and not a user. Or you could use reflection to get the implementation name and try to generate a name... The problem with reflection is that it could effect sub classes and set up a code situation that would be difficult for a junior level developer to understand and maintain...
For that matter you could always generate the name from the class name thru reflection... Though in the long term this could be a nightmare to maintain... It would however reduce the amount of code needed on the implementations, which seems more important than any other concerns. Your could also use attributes here as well, but then you are adding code into the implementations that is equivalent in time/effort as a static constructor and still have the problem off what todo when the implementation does not include that information.

What about something like this:
abstract class Command {
abstract CommandInfo getInfo();
}
class CommandInfo {
string Name;
string Description;
Foo Bar;
}
class RunCommand {
static CommandInfo Info = new CommandInfo() { Name = "Run", Foo = new Foo(42) };
override commandInfo getInfo() { return Info; }
}
Now you can access the information statically:
RunCommand.Info.Name;
And from you base class:
getInfo().Name;

[Suggested solution #1 of 3]
Define an abstract property Name in the interface to force all implementing classes to implement the name property.
(in c#) Add this property as abstract in the base class.
In the implementations implement like this:
public string Name
{
get {return COMMAND_NAME;}
}
Where name is a constant defined in that class.
Advantages:
Name itself defined as a constant.
Interface mandates the property be created.
Disadvantages:
Duplication (which I hate). The exact same property accessor code pasted into every one of my implementations. Why cant that go in the base class to avoid the clutter?

[Suggested solution #2 of 3]
Make a private member variable name.
Define an abstract property Name in the interface.
Implement the property in the base class like this:
public string Name
{
get {return Name;}
}
Force all implementations to pass name as a constructor argument when calling the abstract base class constructor:
public abstract class CommandBase(string commandName) : ICommand
{
name = commandName;
}
Now all my implementations set the name in the constructor:
public class CommandHelp : CommandBase(COMMAND_NAME) {}
Advantages:
My accessor code is centralised in the base class.
The name is defined as a constant
Disadvantages
Name is now an instance variable -
every instance of my Command classes
makes a new reference rather than
sharing a static variable.