I am not sure why the enum there must be public in order to be used with the delegate. I assumed when on namespace level, the whole app can access it, as it is in the scope.
namespace Test
{
enum Days
{
Monday,Tuesday
}
class TestingClass
{
public delegate void DelTest(Days d) /// ERROR, type enum is less accessible
}
}
Your delegate type is actually declared within an internal class, so it's effectively internal too (in some senses, anyway). That's why your example as shown will compile (after adding the semi-colon). To make it break, you'd have to make TestingClass public too. So options:
Leave it as shown
Make the delegate explicitly internal, if you want TestingClass to be public
Make the enum explicitly public, if you want everything to be public
Just to explain why your current code would be broken if TestClass were public: the delegate would be public, and therefore visible outside the current assembly. That means all its parameters and the return type have to be visible too.
Don't forget that the default access level for a member in C# is always "the most restrictive access level that could be explicitly specified for that member" - so for a top-level type (including an enum), the default accessibility is internal.
The accessibility of your enum must match the delegate. Think about how you're going to call it.
new TestingClass.DelTest(Days.Monday).Invoke();
To be able to do this from a different assembly, the Days enum must be public. If you don't want it to be public, change the accessibility of the delegate to match that of the enum, e.g. set both to be internal.
I assumed when on namespace level, the whole app can access it
No, the whole assembly can access it. The default access level is internal.
Edit: When I change your code to use a public class:
enum Days { ... }
public class TestingClass { void M(Days d) {} }
I do get a compile error
Inconsistent accessibility: parameter type 'Test
.Days' is less accessible than ...
And that is what #firefox explains: a parameter-type in a public method must also be public, to avoid inconsistencies. Currently your Days type is less accessible (internal).
This piece of code compiles fine for me too, with the addition of the semi colon.
The error of "parameter type is less accessible than the delegate" would only occur if the class accessibility is raised, as currently they are defined with the same accessibility level, internal.
e.g.
namespace Test
{
enum Days
{
Monday, Tuesday
}
public class TestingClass
{
public delegate void DelTest(Days d); // This will produce an error...
}
}
Related
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();
The following is an interview question. I came up with a solution, but I'm not sure why it works.
Question:
Without modifying the Sparta class, write some code that makes MakeItReturnFalse return false.
public class Sparta : Place
{
public bool MakeItReturnFalse()
{
return this is Sparta;
}
}
My solution: (SPOILER)
public class Place
{
public interface Sparta { }
}
But why does Sparta in MakeItReturnFalse() refer to {namespace}.Place.Sparta instead of {namespace}.Sparta?
But why does Sparta in MakeItReturnFalse() refer to {namespace}.Place.Sparta instead of {namespace}.Sparta?
Basically, because that's what the name lookup rules say. In the C# 5 specification, the relevant naming rules are in section 3.8 ("Namespace and type names").
The first couple of bullets - truncated and annotated - read:
If the namespace-or-type-name is of the form I or of the form I<A1, ..., AK> [so K = 0 in our case]:
If K is zero and the namespace-or-type-name appears within a generic method declaration [nope, no generic methods]
Otherwise, if the namespace-or-type-name appears within a type declaration, then for each instance type T (§10.3.1), starting with the instance type of that type declaration and continuing with the instance type of each enclosing class or struct declaration (if any):
If K is zero and the declaration of T includes a type parameter with name I, then the namespace-or-type-name refers to that type parameter. [Nope]
Otherwise, if the namespace-or-type-name appears within the body of the type declaration, and T or any of its base types contain a nested accessible type having name I and K type parameters, then the namespace-or-type-name refers to that type constructed with the given type arguments. [Bingo!]
If the previous steps were unsuccessful then, for each namespace N, starting with the namespace in which the namespace-or-type-name occurs, continuing with each enclosing namespace (if any), and ending with the global namespace, the following steps are evaluated until an entity is located:
If K is zero and I is the name of a namespace in N, then... [Yes, that would succeed]
So that final bullet point is what picks up the Sparta class if the first bullet doesn't find anything... but when the base class Place defines an interface Sparta, it gets found before we consider the Sparta class.
Note that if you make the nested type Place.Sparta a class rather than an interface, it still compiles and returns false - but the compiler issues a warning because it knows that an instance of Sparta will never be an instance of the class Place.Sparta. Likewise if you keep Place.Sparta an interface but make the Sparta class sealed, you'll get a warning because no Sparta instance could ever implement the interface.
When resolving a name to its value the "closeness" of the definition is used to resolve ambiguities. Whatever definition is "closest" is the one that is chosen.
The interface Sparta is defined within a base class. The class Sparta is defined in the containing namespace. Things defined within a base class are "closer" than things defined in the same namespace.
Beautiful question! I'd like to add a slightly longer explanation for those who don't do C# on a daily basis... because the question is a good reminder of name resolution issues in general.
Take the original code, slightly modified in the following ways:
Let's print out the type names instead of comparing them as in the original expression (i.e. return this is Sparta).
Let's define the interface Athena in the Place superclass to illustrate interface name resolution.
Let's also print out the type name of this as it is bound in the Sparta class, just to make everything very clear.
The code looks like this:
public class Place {
public interface Athena { }
}
public class Sparta : Place
{
public void printTypeOfThis()
{
Console.WriteLine (this.GetType().Name);
}
public void printTypeOfSparta()
{
Console.WriteLine (typeof(Sparta));
}
public void printTypeOfAthena()
{
Console.WriteLine (typeof(Athena));
}
}
We now create a Sparta object and call the three methods.
public static void Main(string[] args)
{
Sparta s = new Sparta();
s.printTypeOfThis();
s.printTypeOfSparta();
s.printTypeOfAthena();
}
}
The output we get is:
Sparta
Athena
Place+Athena
However, if we modify the Place class and define the interface Sparta:
public class Place {
public interface Athena { }
public interface Sparta { }
}
then it is this Sparta -- the interface -- that will be available first to the name lookup mechanism and the output of our code will change to:
Sparta
Place+Sparta
Place+Athena
So we have effectively messed up with the type comparison in the MakeItReturnFalse function definition just by defining the Sparta interface in the superclass, which is found first by the name resolution.
But why does C# chose to prioritize interfaces defined in the superclass in the name resolution? #JonSkeet knows! And if you read his answer you'll get the details of the name resolution protocol in C#.
Parameterless struct constructors, which so far have been prohibited in C#, are now implemented in the Visual Studio 14 CTP (CTP 4 at the time of writing) as an experimental feature.
However, such parameterless constructors must be public. You cannot make them internal or use any other access modifier.
In the C# Design Notes for Aug 27, 2014, I have found an explanation for this:
C#, VB and F# will all call an accessible parameterless constructor if they find one. If there is one, but it is not accessible, C# and VB will backfill default(T) instead. (F# will complain.)
It is problematic to have successful but different behavior of new S() depending on where you are in the code. To minimize this issue, we should make it so that explicit parameterless constructors have to be public. That way, if you want to replace the “default behavior” you do it everywhere.
What is meant by "depending on where you are in the code", and how does enforcing public parameterless constructors solve the issue?
Where you are in the code means that you will get different behaviors depending on the location of the code that uses a struct.
For instance, if you have a parameterless constructor that's marked as internal, the behavior varies if you create an instance from the same assembly in which the struct is defined or from another assembly.
In first case the parameterless constructor is called because its accessible and in second case default(T) is called. Same situation is enountered for private and protected constructors.
For example, suppose we have two assemblies, A and B:
//Assembly A
public struct SomeStruct
{
public int x = 0;
internal SomeStruct()
{
x = 10;
}
}
public static void DoSomething()
{
var someStruct = new SomeStruct();
Console.WriteLine(someStruct.x); // prints 10
}
//Assembly B
public static void DoAnotherThing()
{
var someStruct = new SomeStruct();
Console.WriteLine(someStruct.x); // prints 0
}
This leads to inconsistent behavior depending on where you are in the code and the reason why they forced using public constructors.
You can be "in a place in the code" in the following meaning:
in the context of your struct, i.e.:
struct X
{
//...
public X CreateNew() { return new X(); }
}
in the context of your assembly:
new X(); // from the same assembly
in another assembly
new X(); // from another assembly
So, the mechanism you speak of, would have to behave differently for exactly the same piece of code (new X();), in each of these contexts. In the first example, you can use the constructor regardless of its access modifier. In the second example, you can access one if it's public or internal. In the third one, it could've been used only if it's public.
Making it public simplifies the situation, as it will be accessible in all of these contexts.
According to MSDN here and here (as well as the accepted answer to this qstn), the default accessibility for enums is public.
However, this code:
public class Test
{
enum Color { RED, BLUE, GREEN };
public void SetColor(Color c) { }
}
will raise this compile error:
Error 1 Inconsistent accessibility: parameter type 'Test.Color' is less accessible than method 'Test.SetColor(Test.Color)'
(which is the same error you get when you set the enum as private.) This error can only be resolved by explicitly modifying enum as public. Is the documentation incorrect?
[I'm compiling with C# 2010 and .NET 4.0.]
That is not true.
The default accessibility for enum types is the same as any other type; internal for top-level types and private for nested types.
The pages you linked to state that the default (and, in fact, only) accessibility level for enum members (Red, Blue, etc) is public.
The mentioned MSDN articles and SO answer refer to "enum member" - i.e. e.g Test.Color.RED, not Test.Color as the enum itself.
Test.Color is a member of class - thus private.
That table is referring to the members; the members are "RED", "BLUE" and "GREEEN", and are indeed public literal constants, and accessibility specifies are not permitted.
Contrast, say, to the members of a class (fields, methods, constants, etc); here, as per the table, the default is "private", although you can specify higher accessibility.
I believe that because you're declaring inside the class without a modifier, it assumes to be private as it's the standard behavior in a class. Specify public that should solve the issue. However, note that Code Analysis will recommend this enum be placed outside the class.
it is because you dont have public, protected, internal on your enum, it takes the default value (which is internal for classes and enums)
sorry for the confusion, you can't make the property public because the enum is private
the public property would be externally public should someone use your program and the compiler tells you about it
If I declare an interface, or a type as private in one file, is it private to that file or the namespace?
The compiler generates an error for File2: 'Error 14 Inconsistent accessibility: parameter type 'DIDemo1.IImageRepository' is less accessible than method 'DIDemo1.ImageGetter.ImageGetter(DIDemo1.IImageRepository)'
What I don't understand is that MyClass can use the interface but ImageGetter class cannot.
File1:
namespace DIDemo1 {
interface IImageRepository {
Image[] GetImages();
}
public class MyClass : IImageRepository {
#region IImageRepository Members
public Image[] GetImages() {
return new Image[] { };
}
#endregion
}
}
File2:
namespace DIDemo1 {
public class ImageGetter {
IImageRepository _repo;
public ImageGetter(IImageRepository repository) {
_repo = repository;
}
public Image[] GetImages() {
return _repo.GetImages();
}
}
}
Since you did not specify an access modifier for your interface, it defaults to internal, which is lower than public. That means only code in the same assembly are aware of its existence.
A public class can implement an internal interface, because other code inside that same assembly would see your class with the interface, and code outside would simply see the public class, with no interface.
However, in File2, you are making an internal interface part of that class' public contract - that is, your class is public, which means any code can see it, but in order to use it they must also be able to understand the types in the constructor. Since one of the types required in the constructor is internal, external code cannot understand it, and this contract is impossible to fulfill.
What I don't understand is that MyClass can use the interface but ImageGetter class cannot.
ImageGetter can use the interface, it just can't present it in one of its method signatures which are more accessible. Likewise if MyClass tried to use it in one of its method signatures you'd get the same error. Read below.
Top level interfaces, structs, and classes default to internal access. To fix your problem put public before your interface declaration.
internal types in C# are accessible only within the same assembly.
You can't use a more restrictive access modifier in a less restrictive signature for obvious reasons. (How could someone who can't access the more restrictive type call the function for example?)
No, which file the code is in is irrelevant. The interface is private to the namespace, not the file.
The error message is not because the ImageGetter class can't reach the interface, it's because the class can't be used from outside the namespace.
The difference lies in how you use the interface. The class MyClass only implements the interface, so you can still use the class even if you can't use the interface. The constructor in the ImageGetter class requires a reference to the interface, so you can't use that class without also having access to the interface.
Interfaces and classes default to internal accessibility (because there is no concept of a class being private inside a namespace). The error explains what happens there - IImageRepository is less accessible (it is internal) than ImageGetter constructor, which exposes IImageRepository as a parameter.
Basically a public method on ImageGetter exposes a type that is internal. This is not allowed in C#.