Problem: When I execute my code it pulls up the code correctly from the inherited base class and changes the text of the base form correctly. But as soon as I, in debugger mode in VS2013, come back into the derived class and step over the InitizlieComponent(); call everything is reverted back. When I say 'reverted back' I mean that thing go back to the way that they were in the designer for the derived form.
All help would be appreciated!
Derived Class
public partial class appSuiteMenu : App.baseForm
{
public appSuiteMenu()
: base("App Suite")
{
InitializeComponent();
}
}
Base Class
public partial class baseForm : Form
{
public baseForm() { InitializeComponent(); } //Required or designer breaks
public baseForm(string formTitle=null)
{
this.initialize(formTitle);
}
private void initialize(string formTitle)
{
base.text = formTitle + " - " + //Other objects are called from the class
}
public override string Text
{
get
{
return base.Text;
}
set
{
base.Text = value;
}
}
}
My guess would be the second call to the "InitializeComponent()" inside the derived class.
What is does, is exactly what you said. It overrwrites everything from the base initialization.
I believe you can remove it and it'll be fine:
public appSuiteMenu()
: base("App Suite")
{
}
Read more about it in here: http://www.dotnetperls.com/initializecomponent
Edit:
Here is some tests I did with two forms. One is derived from the other. The base form hase a label. The second from adds another label. When creating a form of the derived type, tou get a form with two labels. What I did was use InitializeComponent(); in both base and derived forms.
The code:
public partial class BaseForm : Form
{
public BaseForm()
{
InitializeComponent();
label1.Text = "asdf";
}
}
...
public partial class DerivedForm : BaseForm
{
public DerivedForm()
{
InitializeComponent();
label2.Text = "asdfasfd";
}
}
What happens in execution of the code is that the base initialization happens. Then the derived initialization adds only the add functionality.
It seems pretty straightforward, but Iv'e noticed you had only one InitializeComponent(); in the code above that will actually happen.
Dave,
Your edited posted is nearly what I ended up doing to correct my problem. Since I was overriding the .Text() property of the base form, I found that I didn't even have to pass anything in the constructor. Simply setting the form text in the code, or designer, changed everything for me.
Related
I have a Visual Studio 2010 Windows Forms app which includes a Form base class that other classes will inherit. The base class' constructor takes a parameter that the child classes will pass to the base class.
Example:
public partial class BaseForm : Form
{
public BaseForm(int number)
{
InitializeComponent();
}
}
public partial class ChildForm : BaseForm
{
public ChildForm(int number)
: base(number)
{
InitializeComponent();
}
}
The problem that I'm running into is, when I attempt to open the ChildForm in VisualStudio's Design View mode, I receive the following error:
Constructor on type 'MyProject.BaseForm' not found.
Note: regardless of the error, the project compiles and runs fine.
I can avoid the error if I overload the constructor with one that does not contain any parameters.
Example: (This gets rid of the error)
public partial class BaseForm : Form
{
public BaseForm(int number)
{
InitializeComponent();
}
public BaseForm()
{
InitializeComponent();
}
}
public partial class ChildForm : BaseForm
{
public ChildForm(int number)
: base(number)
{
InitializeComponent();
}
}
My question is, how can I create a base class that does not include a parameterless constructor and avoid the Design View error?
That is completely impossible.
The form you see in the design view is an actual instance of your base class.
If there is not default constructor, the designer cannot create that instance.
You can mark the constructor with the [Obsolete("Designer only", true)], and make it throw an exception if called when not in the designer, to prevent other people from calling it.
You need to adjust your BaseForm output type, In the properties for the project, change the Output type from Windows Application to Class Library.
ref:
https://learn.microsoft.com/en-us/dotnet/framework/winforms/advanced/walkthrough-demonstrating-visual-inheritance
I have the following custom Form (MyFrm) which inherits from Form.
public class MyFrm<T>: Form where T: class
{
}
And following is my Form1:
public partial class Form1: MyFrm<CONTACTS_BASE>
{
public Form1()
{
InitializeComponent();
MyInitialize();
}
public void MyInitialize()
{
}
}
as can be seen, there is nothing exceptional, However, when right click and select view designer I get the following error:
The designer could not be shown for this file because none of the classes within it can be designed. The designer inspected the following classes in the file:
Form1 --- The base class 'MyGym.Controls.MyFrm' could not be loaded. Ensure the assembly has been referenced and that all projects have been built.
when I remove the part below and edit my Form1 accordingly I get no errors when I go to the designer mode.
: Form where T: class
Why am I facing this issue? is there a fix for this?
Thanks
I believe you need to explicitly provide the InitializeComponent() method so that the Visual Studio IDE (Designer) works properly.
public class MyFrm<T> : Form
where T : class
{
public MyFrm() : base()
{
InitializeComponent();
}
private void InitializeComponent()
{
}
}
and then chain the constructors it together
public partial class Form1 : MyFrm<CONTACTS_BASE>
{
public Form1() : base()
{
InitializeComponent();
MyInitialize();
}
public void MyInitialize()
{
}
}
Note that : base was added to the constructor. However, in this example it's a bit overkill as the base constructor would already be called implicitly. I provided this addition, due to this answer. It states you must keep the constructor parameter-less in your base class.
Well the title should actually explain the problem quite well. Consider I create a new UserControl, however in my application many of those elements share a common code, and they are part of a "subgroup" of user controls.
The logical thing is to "inject" a class between the generated CustomUserControl and UserControl;
Something akin to:
public abstract class CommonCustomControl : UserControl
{
public CommonCustomControl(int v, string other) {
}
}
public partial class CustomUserControl : CommonCustomControl
{
CustomUserControl(int v, string other) : base(v, other) {
}
}
Now the problem with this is, is that the class is only "partially" generated by visual studio. So changing the generated CustomUserControl class gives an error:
"Base class differs from declared in other parts"
How can I prevent this error? While still being able to actually design my user control element in visual studio's gui designer?
I have tried already the answer provided by this question. But it seems to not work at all. (Maybe since that talks about winforms instead of the WPF version)
[TypeDescriptionProvider(typeof(AbstractControlDescriptionProvider<InterfaceHandler, UserControl>))]
public abstract class CommonCustomControl : UserControl
{
private readonly int _v;
private readonly string _other;
public CommonCustomControl(int v, string other) {
_v = v;
_other = other;
}
}
public partial class CustomUserControl : CommonCustomControl
{
public CustomUserControl(int v, string other) : base(v, other) {
}
}
What goes wrong?
You only have your C# code on view here but I'll take a punt at what this might be.
The UserControl you are declaring inherits from a base class.
The UserControl is also a partial class.
Partial classes normally mean that there is other code for this class elsewhere.
The error is stating that the base class is different between the two partial classes.
If you do not have your own second partial class for this UserControl (i.e. it is not just a class, but an actual User Control), then I assume the rest of the definition will be in the XAML.
Depending on how you are implementing your controls:
You may have this:
<UserControl x:Class="NamespaceHere.CustomUserControl"> ... </UserControl>
It should look like this:
<CommonCustomControl x:Class="NamespaceHere.CustomUserControl"> ... </CommonCustomControl>
If not, could you show your XAML too?
A little background on my project:
I'm making a multi-form application, which consists of 1 mainform, and 6 childforms that can be called from the mainform, but only 1 childform can be active at a time. These childforms share certain parts of code, which I do not want to copy. To solve this, I have a codefile within the same namespace which holds the nessaccary code.
This codefile however, needs access to certain properties of the currently active childform.
My search has come down to using an interface to extract the needed information from the active childform.
My code is currently looking like this:
Interface:
public interface Interface1
{
TabControl tabControl_Buizen_
{
get;
}
TabPage tabPage_plus_
{
get;
}
}
Childform:
public partial class Childform : Form, Interface1
{
Interface1 dummy;
public TabControl tabControl_Buizen_
{
get { return this.tabControl_Buizen; }
}
public TabPage tabPage_plus_
{
get { return this.tabPage_plus; }
}
Methods_newTabPage methods = new Methods_newTabPage(dummy);
}
Codefile:
public class Methods_newTabPage
{
private readonly Interface1 form;
public Methods_newTabPage(Interface1 formInterface)
{
this.form = formInterface;
}
}
As you can see I'm using Methods_newTabPage methods = new Methods_newTabPage(dummy); to be able to call methods in my codefile, but the codefile requires the interface to be passed (which I filled as "dummy"). This however pops the error "A field initializer cannot reference the non-static field, method, or property Childform.dummy".
How can I let the childforms access the methods in the codefile, while also giving the codefile access to certain controls in differing childforms?
The error is easy to fix: just make dummy static.
static Interface1 dummy;
However, I don't think that will help you much. Why are you passing this dummy to Methods_newTabPage anyway? This will lead to NullReferenceExceptions inside the code file because dummy was never initialized with anything.
Don't you rather want to pass this, i.e. the current instance of Childform?
But you cannot just exchange dummy with this like so:
// Compiler error "Keyword 'this' is not available in the current context".
Methods_newTabPage methods = new Methods_newTabPage(this);
Instead you have to add a constructor that creates Methods_newTabPage:
public partial class Childform : Form, Interface1
{
private Methods_newTabPage methods;
public Childform()
{
methods = new Methods_newTabPage(this);
}
public TabControl tabControl_Buizen_ { get { return this.tabControl_Buizen; } }
public TabPage tabPage_plus_ { get { return this.tabPage_plus; } }
}
Try adding a constructor that initializes the field methods.
Also I don't see how that dummy makes sense. Instead initialize methods via methods = new Methods_newTabPage(this); in the constructor.
Here's my wish to create something abstract in WPF. You've got a main window (called main for example, even if it's not correct we don't care) with two buttons. Those two buttons have the same function : they open a new window, the same for both of them, but with different things inside. So I decided to create an abstract class to rule them like that :
public abstract (partial ?) class A : Window
{
public A()
{
InitializeComponent(); // Not sure about that, it's kinda weird to use it here no ?
}
...
}
public partial class B : A
{
public B()
{
InitializeComponent(); // Since it's already in A I shouldn't have to use it here right ?
}
...
}
public partial class C : A
{
public C()
{
InitializeComponent(); // Same thing here...
}
...
}
Debugging gives me something like : "error CS0263: Partial declarations of 'namespace.B' must not specify different base classes".
Removing 'partial' from A class gives : "error CS0260: Missing partial modifier on declaration of type 'namespace.A'; another partial declaration of this type exists".
I know that 'partial' specifies if a class has another part of her somewhere else (like the xaml file beside the cs one), so I guess the abstract class has to be partial too since it contains my controls. Maybe the B class shouldn't be partial ?
I know (memories) it works with Windows Forms, but there's no xaml files so it's easier, and I didn't find any useful tips. I think I understood that this problem occurs when I don't change something in my xaml file, which doesn't works as simply as "class : abstract class". Maybe the subclass thing ?
Please note that I'm a beginner in WPF apps, so I thank you in advance if your answer is as detailed as possible.
Thanks !
You need to define your base class all in code without using XAML :
Code for class A :
public abstract class A : Window { }
Code for class B :
public partial class B : A
{
public B()
{
InitializeComponent();
}
}
xaml for class B :
<yourNamespace:A x:Class="yourNamespace.B"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:yourNamespace="clr-namespace:yourNamespace"...
A C# partial class is one that is defined over two or more source files. The other 'part' of Window is generated by Visual Studio, and includes things like InitializeComponent()
If you want a base Window class, then it has to be defined entirely in code, and have no XAML component. It will then no longer be a partial class.
public abstract class WindowA : Window
{
// define base methods here
}
Then you can derive WindowB from WindowA:
public partial class WindowB : WindowA
{
public WindowB()
{
InitializeComponent();
}
}
But you also need to do it in the other 'part', i.e. in XAML, so in WindowB's XAML file, the root Window tag needs to be changed to:
<wpfApp:WindowA x:Class="WpfApp.WindowB"
wpfApp:WindowA ="clr-namespace:WpfApp"
(you'll need to change the namespace appropriately)
This will generate the other 'part' deriving from WindowA, so there will be no inconsistency.
The InitializeComponent() method should be called in each derived class' constructor, as it's specific to that class, i.e. in this case, the other 'part' is generated from the XAML, and defines an InitializeComponent() with resourceLocator code that specific to WindowB.