I have defined a user control, ExpressionControl, under the namespace:
TriggerEditor.UserControls
I have a form, "IfEditor", under the namespace:
TriggerEditor.Forms
When I add an instance of my control to the form (naming it expCondition), the following code is generated in the Designer to create the control:
this.expCondition = new TriggerEditor.UserControls.ExpressionControl();
This results in the following compilation error:
The type name 'UserControls' does not exist in the type 'TriggerEditor.Forms.TriggerEditor'
I don't understand why it is looking in "TriggerEditor.Forms.TriggerEditor"; that's not what the code says. Now, I can resolve this error manually by modifying the line, removing the "TriggerEditor." that preceeds "TriggerControls", as such:
this.expCondition = new UserControls.ExpressionControl();
This satisfies the compiler, however I obviously don't want to do this every time I add an instance of my ExpressionControl to a form. How do I avoid this situation?
It looks like you might have a TriggerEditor class within the TriggerEditor.Forms namespace; is this the case?
If so, because the TriggerEditor class is within your current namespace, you are "closer" to this class, and therefore it is looking for a subclass.
Avoid using the same name for a class and a namespace!?
Apparently, in the namespace TriggerEditor.Forms, you have a class named TriggerEditor in the same namespace as your IfEditor class.
So, when looking for TriggerEditor.UserControls.ExpressionControl, the compiler looks in the TriggerEditor class (which is in the same namespace, so closer) instead of the TriggerEditor namespace...
Normally, to avoid that, you would use a namespace alias qualifier, but being in a Designer generated class, you can't really control that.
Related
I have a class called Message. It is located inside MyProgram namespace. The problem is that System.Windows.Forms has also a Message class, so whenever I want to use classes from both of the namespaces, I need to write MyProgram.Message to refer to my class, which is very tedious.
I hoped this line could work:
using static Message = MyProgram.Message;
but I get the following error:
a 'using static' directive cannot be used to declare an alias
Is there a way to force the code to recognize Message as MyProgram.Message? Also, changing my class's name is not a real solution. :P
using static is for static members, not nested types.
A regular using directive will work fine.
using Message = MyProgram.Message;
Unfortunately, due to issues that are frustratingly out of my control, I'm forced to use components with namespaces which I cannot change. Because of the way they have structured them, it's causing collisions in the generated code-behind.
Again, unfortunately, I do not have access to the code which defines these namespaces so they cannot be changed. Down-voting this does not help anyone, especially without a reason/explanation. Also, I've also tried demonstrating the issue to the owners explaining why this is a very bad design, but I've been told for other reasons, changing them is not an option, so I'm forced to find a work-around.
Here's a simplified example to illustrate the issue. Consider a solution with two projects, a 'Core' library, and the consuming application:
Items in 'Core' Library
ModelA (Namespace: SomeFeature.Core.Models)
ModelB (Namespace: SomeFeature.Core.Models)
**Items in 'ConsumingApp' (References 'Core') **
MainWindow (Namespace: ConsumingApp.SomeFeature)
TestControl (Namespace: SomeFeature.Controls)
The cause of the collision can be explained in three steps:
SomeFeature is both the root of one namespace, and a child of another
TestControl is defined as being in the rooted version of the namespace (same as the library), not the one MainWindow is in.
Code-generation ends up placing the generated variables for those XAML elements in the namespace scope of MainWindow, not that matching what's actually in the XAML.
Now if these were manually-defined variables in non-generated code-behind, dealing with this is easy. By simply adding the prefix global:: it 'roots' the namespace you're typing, thus removing all ambiguity.
namespace ConsumingApp.SomeFeature{
public partial class MainWindow{
// Note the 'global::' prefix
global::SomeFeature.Controls.TestControl MainTestControl { get; set; }
}
}
The above will ensure that it always resolves relative to the global SomeFeature namespace and never the nested ConsumerApp.SomeFeature namespace. Pretty straight forward.
However, the auto-generated code-behind from the XAML parser doesn't include that global:: prefix, so in the generated code, you actually get this:
namespace ConsumingApp.SomeFeature{
public partial class MainWindow{
// Note: without the 'global::' prefix, this resolves to
// 'ConsumingApp.SomeFeature.Controls.TestControl'
// which doesn't actually exist, causing the mentioned issue.
SomeFeature.Controls.TestControl MainTestControl { get; set; }
}
}
Which results in this error:
Error CS0234 The type or namespace name 'Controls' does not exist in the namespace 'ConsumingApp.SomeFeature' (are you missing an assembly reference?)
As noted in the code comments, this is because it's not looking for this class path...
SomeFeature.Controls.TestControl
but rather this one:
ConsumingApp.SomeFeature.Controls.TestControl
which doesn't exist, ergo the error.
The fix would be to somehow get the auto-generated code to explicitly output the global:: but I don't know how to do that, or even if it can be done.
Things I've tried:
Arguing for them to change their namespaces! (I lost!)
Explicitly referencing the assembly in the XAML import:
Defining aliases in the non-generated code-behind
Searching for aliases in the XAML world (not found)
Avoiding naming the element, and instead manually searching for the control via other properties. (Horrible, but this does work!)
So is there anything that can be done here to get the code-generator to include the 'global::' prefix, or is there another way to do this?
In XAML, a custom namespace can be imported with an xmlns directive:
xmlns:custom="clr-namespace:GreatStuff"
In C#, that namespace can be imported with
using GreatStuff;
Moreover, evaluation of that namespace based on the global (root) namespace can be enforced as follows:
using global::GreatStuff;
How can I enforce evaluation based on the global namespace in XAML?
Background:
I am facing the (admittedly slightly obscure) situation that there is such a namespace global::GreatStuff, which contains a WPF control class named ... GreatStuff (i.e. fully qualified, that's global::GreatStuff.GreatStuff in C#). In the same namespace, I want to use that control in a WPF window.
Interestingly, in this constellation, I cannot use the Name/x:Name attribute on any controls of type global::GreatStuff.GreatStuff in my XAML file for the window:
The type name 'GreatStuff' does not exist in type 'GreatStuff.GreatStuff'. (CS0426)
Note that the very same file compiles fine if I do not specify a Name/x:Name attribute!
Now, why should the compiler assume that by setting a Name/x:Name attribute, I am trying to access something called GreatStuff.GreatStuff.GreatStuff?
The answer can be found by examining the .g.cs file generated from the window XAML file. In that file, the XAML snippet
<custom:GreatStuff x:Name="stuff"/>
gets compiled to the following C# snippet:
internal GreatStuff.GreatStuff stuff;
That is, the fully-qualified name is used, but without the explicit global namespace marker.
Of course, as a field in a class in namespace global::GreatStuff, all of this is wrapped in
namespace GreatStuff {
And so, the poor C# compiler cannot help but assume that stuff is supposed to be of a type global::GreatStuff.GreatStuff.GreatStuff. This could be avoided if in
xmlns:custom="clr-namespace:GreatStuff"
I could enforce that any mentions of that namespace prefix could be converted while enforcing the global namespace.
For reasons external to this question, changing the namespace and/or class names is not an option here.
This issue only occurs when all of the following are true:
You have a class with an identical name as the namespace containing it.
Within that same namespace, you have a xaml file with an instance of an object that is also declared within that namespace.
That specific object instance is given a Name or x:Name attribute.
If you cannot modify anything to make any one of those conditions false, then you are working with some very serious restrictions.
As far as I know, this is a limitation of the xaml compiler, and you will need to contact Microsoft about resolving it. The only other thing I can think of would be to try to work around it with a custom build process that builds xaml, allows you to edit the generated files, then builds the code. That would require some research to figure out how to set up.
I am very new to c# and this is probably a very n00b error.
For this project I have been handed existing code to work with. The structure of the code is that it has a main solution with simulation as a supporting namespace.
I copied one of the classes (Adt_12) from simulation namespace that I want to modify and renamed it (Pb_cs2). The way I copied is, was to click on save as.. and then changed the file name to the new name I want. And then changed the public class name (and the constructors) to this new file name. I have rebuild 'simulation' and it rebuilts fine.
But when I try to call Pb_cs2, it is throwing the above 'the type or namespace named Pb_cs2 could not be found'.
The way I am using it in the executable class in main; is
public static Pb_cs2 pb; (which was originally using Adt_12).
But it can still find Adt_12 in the solution and namespace. Just no Pb_cs2. I have rebuilt and built the solution.
The common error of .NET framework is not relevant.
Any ideas why this is happening and how I can fix this? I really dont want to modify the original file.
Take a look here. Visual Studio saying name doesn't exist in current context
You need to make sure:
Your class name and namespace are not the same, like Pb_cs2.Pb_cs2 as this will confuse the compiler
You can fully qualify the path to the class i.e. MyNamespace.MyNestedNameSpace.MyClass
You can use a shortcut i.e. using MyClass = MyNamespace.MyNestedNamespace.Class1
Ensure that your projects are targeting the same framework i.e. .NET 4.0 / .NET 4.0 Client Profile.
You might have a collision where your class has the same name as another class, in which case, use option 2, or rename your class to something else.
If your class name does not appear in intellisense, then it does not know where to look for it. You can right click the class and click "Resolve" which will give you some options on how to qualify your class.
...that is all I can think of right now!...Good Luck!
Edit:
Look up C# stylistic conventions... those class names are ugly!!!
Add a reference to the namespace which contains the class you are calling. So you might have something like
namespace SomeNamespace
{
public class Pb_cs2
{
...
}
}
so you need to add using SomeNamespace; to the declarations at the top of the file that is attempting to call your class. Or call the class using the fully qualified name
SomeNamespace.Pb_cs2 pbcs2 = new SomeNamespace.Pb_cs2();
You can also create a alias to the namespace when you reference it like
using NS = SomeNamespace;
then the above explicit reference can be called like
NS.Pb_cs2 pbcs2 = new NS.Pb_cs2();
I hope this helps.
Do it this way to be sure the calss is known by your solution.
Project->addclass
select class if it isn't selected by now.
Name it and then add the new class.
it should appear in your solution explorer.
Now copy paste the code. rename the class the namespace should be fine.
and you should be okay with that.
During a refactoring, I added a generic type parameter to MyControl, a class derived from UserControl. So my class is now MyControl<T>.
Now I get an error at runtime stating that the embedded resource file MyControl`1.resources cannot be found. A quick look with .NET Reflector shows that the resource file is actually called MyControl.resources, without the `1.
At the start of the MyControl<T>.InitializeComponent method there is this line which is probably the one causing problems:
System.ComponentModel.ComponentResourceManager resources =
new System.ComponentModel.ComponentResourceManager(
typeof(MyControl<>));
How do I force the ComponentResourceManager to use the embedded resource file MyControl.resources? Other ways to resolve this issue are also welcome.
Turns out you can override the resource filename to load by inheriting from ComponentResourceManager like this:
using System;
using System.ComponentModel;
internal class CustomComponentResourceManager : ComponentResourceManager
{
public CustomComponentResourceManager(Type type, string resourceName)
: base(type)
{
this.BaseNameField = resourceName;
}
}
Now I can make sure that the resource manager loads MyControl.resources like this:
System.ComponentModel.ComponentResourceManager resources =
new CustomComponentResourceManager(typeof(MyControl<>), "MyControl");
This seems to work.
edit: the above line is overwritten if you use the designer, because it is in the
generated code region. I avoid the designer and make use of version control tools to revert any unwanted changes, but the solution is not ideal.
In addition to Wim's technique, you can also declare a non-generic base control that has the same name as your generic class, and have your generic control/form derive from that non-generic base class.
This way you can trick both the designer and the compiler into using the resource file from your generic class, and you get permanent designer support once the base class is setup without having to fiddle in the .designer file everytime you rebuild :
// Empty stub class, must be in a different file (added as a new class, not UserControl
// or Form template)
public class MyControl : UserControl
{
}
// Generic class
public class MyControl<T> : MyControl
{
// ...
}
The only requirements are to have exactly the same name for your generic class and its base class, and that the base class must be in another class file, otherwise the designer complains about not finding one of the two classes.
PS. I tested this with forms, but it should work the same with controls.
On my Visual Studio 2008 I have this error:
System.ComponentModel.ComponentResourceManager resources = new System.ComponentModel.ComponentResourceManager(typeof(MyControl));
Using the generic type 'WindowsFormsApplication1.UserControl1' requires '1' type arguments.
Notice that in my case code was generated without parentheses, <>, after the class name.
It is becoming interesting, see ImageList autogenerates non-compiling code in a Generic User Control.
What they said:
Posted by Microsoft on 7/6/2005 at 2:49 PM
This is an interesting bug. You've hit upon a generic scneario that we do not support in the Windows Forms designer. We will not be able to add support for this in the Whidbey (my note: Visual Studio 2008?) release. We will consider this for a future version. As a workaround, you can use the designer to create a none generic UserControl with a public Type property and then create a generic class that inherits from it and passes T into the base classes Type property.
I suppose this control cannot be designed in the Visual Studio forms designer either.
The simplest and easiest workaround is to make a dummy class for the autogenerated typeof(). You do not need to inherit from it or even expose it to the outside:
// Non-generic name so that autogenerated resource loading code is happy
internal sealed class GridEditorForm
{
}
(In my experience, the time required getting the designer to work around generics was not worth the ideal coolness generics can provide. I won't be using generic windows forms or controls again.)