Develop Reference

How to use a dynamic button in another class

I want to make a dynamic button and control it.
But I got an error in the line
MainMenuButton(true, Form);
How can I correct it?
Form1.cs
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
UI Teemp;
ClientSize = new Size(Bounds.Width, Bounds.Height-35);
Teemp.MainMenuButton(true, Form);
}
}
and UI.cs
class UI
{
public void MainMenuButton(Boolean Mode, Form Form1)
{
if (Mode == true) //Create
{
System.Windows.Forms.Button StartB = new System.Windows.Forms.Button();
Form1.Controls.Add(StartB);
StartB.Text = "Start";
StartB.Top = 300;
//StartB.Bottom = 100;
StartB.Left = 400;
}
else
{
// this.Controls.Remove(StartB);
}
}
}

You have to create an instance of the UI class first. UI Teemp; only declares a local variable of type UI but does not initializes it with an UI object instance. One cannot use uninitialized local variables.
When declaring the Teemp variable, you can at the same time initialize it with an UI object instance:
UI Teemp = new UI();
There is a second problem with your code. When invoking MainMenuButton, you will need to pass the Form object instance. In your code, Form is a type name and does not refer to an object instance. Use the this keyword:
Teemp.MainMenuButton(true, this);
The this keyword refers to the current instance of the class in which it is being used. With regard to your example, this would refer to the Form1 object instance.
I also want to comment on another thing. Technically not being a problem, but naming your second argument of the MainMenuButton "Form1" can be confusing, since there is also a type named "Form1". With regard to C# it is generally recommended that the first letter in variable and argument names is lowercase, whereas the first letter in type names should be uppercase. Hence the source code for your MainMenuButton method could perhaps look similar like this:
public void MainMenuButton(bool createButton, Form form)
{
if (createButton)
{
System.Windows.Forms.Button startB = new System.Windows.Forms.Button();
form.Controls.Add(startB);
startB.Text = "Start";
startB.Top = 300;
//startB.Bottom = 100;
startB.Left = 400;
}
else
{
// this.Controls.Remove(startB);
}
}
Keeping variable and argument names different from type names avoids confusion when reading and writing code, thus lowering the risk of introducing bugs :)

C# - dll event handler

I am setting a .dll file to create a new form and a new button, but i want that button to do something. Is it possible to create a event handler in a dll file?
public static byte sbuton( string er, int by,int re)
{
Form fg = new Form();
fg.Show();
Button b1 = new Button();
fg.Controls.Add(b1);
b1.Text = er;
b1.Location = new Point(by, re);
return 0;
}
This is the code that creates a form with a button in it.
When I try to create a new event handler, as I would in a form, I get this error: "An object reference is required for the non-static field, method or property".
public static byte sbuton( string er, int by,int re)
{
Form fg = new Form();
fg.Show();
Button b1 = new Button();
fg.Controls.Add(b1);
b1.Text = er;
b1.Location = new Point(by, re);
b1.Click += new EventHandler(b1_click);
}
private void b1_click(object sender , EventArgs e)
{
}
This is the code from the form where I want use the dll
private void button1_Click(object sender, EventArgs e)
{
if (richTextBox1.Text.Contains("add") && richTextBox1.Text.Contains("buton") && richTextBox1.Text.Contains("text"))
{
form.sbuton("buton", 10, 10);
}
}
This creates a button, but nothing happens when the button is clicked, because no event handler is assigned to it in the .dll file.
And also,sorry for the bad english,it is not my native language.
What can i do?
Thanks!

It's not clear from your question what the context is. Without a good, minimal, complete code example it's difficult to provide a really good answer.
But in your example, it appears that your event handler is in the same DLL (and I assume, the same class) as the sbuton() method. If that's the case, then all you need to do in order to use the event handler is make it a static method:
private static void b1_click(object sender , EventArgs e)
{
}
Now, since you didn't post any of the code in the method, never mind the full context, it's not certain that would work. I.e. if there is a good reason for that method being a non-static method, then you will have to subscribe the event handler by referring to the method with a reference to an actual instance of the containing class. If that's the case, then the question commenter Daniel Kelley suggests, An object reference is required for the non-static field, method, or property?, may turn out to be appropriate for your needs after all.
Finally, note that none of this has anything to do with the code being in a DLL. You would have run into this same problem had your sbuton() method been in the same project from which you're calling it.

c# objects modification: a strange behaviour

I'm developing a WPF C# application and I have a strange behaviour in modification of objects. I try to explain it in general way.
Suppose that you have an object of a class described as follows:
public class A
{
int one;
bool two;
List<B> listofBObjects;
}
where B is:
public class B
{
int three;
int four;
}
I pass an instance of A class and an instance of B class from a window to another, only defining two variables of type A and B in the second window and passing them before the Show() method, with the following code, executed into an instance of window FirstWindow:
SecondWindow newWindow = new SecondWindow();
newWindow.instanceOfA = this.instanceOfA; //instanceOfA is of type A
newWindow.instanceOfB = this.instanceOfA.listOfBObjects[0]; //instanceOfB is of type B
newWindow.Show();
If I have to repeat this code twice(that is, opening twice the window), in the first execution everything works as expected, infact if I modify values in instanceOfB variable, I see the modification also in instanceOfA variable. But, in the second execution, the modification in instanceOfB does not affect instanceOfA...
The modifications are done in newWindow. For example:
this.instanceOfB.three++;
this.instanceOfB.four--;
Imagine that you are in the FirstWindow. Click on a button and SecondWindow opens, passing both variables as described above. In SecondWindow, do some modifications, click on OK and SecondWindow closes, returning control to FirstWindow. If I reclick on the same button, I reopen SecondWindow. If I do modifications now, they do not affect both variables.
I try to have a look (in VS2012) at both variables in the console with control expression and I see that, in the first pass of code, both variables changes when code above is executed but, in the second pass of code, only instanceOfB changes...
EDIT:
Following the code that I use to pass parameters to SecondWindow...types are explaind below
IntermediatePosition obj = ((FrameworkElement)sender).DataContext as IntermediatePosition; //IntermediatePosition is Class B
IntermediatePositionsSettingsWindow ips = new IntermediatePositionsSettingsWindow();
ips.currentIntermediatePosition = obj;//this is the instanceOfB
ips.idxOfIpToModify = obj.index;
ips.currentSingleProperty = this.currentPropertyToShow; //this is the instanceOfA object
ips.sideIndex = this.sideIndex;
ips.ShowDialog();
Consider that obj is given by a button selection into a datagrid, in which each row represents an IntermediatePosition object. In the datagrid, there is a column button and, clicking by buttons, IntermediatePositionsSettingsWindow is opened with the proper data
EDIT:
I've performed the folloqing check:
this.currentPropertyToShow.sides[this.sideIndex].intermediatePositionList[i].Ge‌​tHashCode() == obj.GetHashCode()
where i is the index of related IntermediatePosition object. At first usage of IntermediatePositionsSettingsWindow the objects result equals, but in second usage they are different
Why this thing happens?
If it is needed any other clarification, I will edit the question
Thanks

It's difficult to give a proper answer to this, as there is insufficient code to correctly work out the issue. However, if you are databinding, then I believe you need to implement this interface. It is possible that you're issue is simply that you're model is not reflecting the changes to the screen.

I can't reproduce your problem. Here's a simplified representation of your class relation (as I understood from your question). Please let us know if this is correct:
public partial class MainWindow : Window
{
internal A instanceOfA;
internal B instanceOfB;
public MainWindow()
{
InitializeComponent();
instanceOfB = new B() { };
instanceOfA = new A() { listOfBObjects = new List<B>() { instanceOfB } };
}
private void Button_Click(object sender, RoutedEventArgs e)
{
SecondWindow newWindow = new SecondWindow();
newWindow.instanceOfA = this.instanceOfA; //instanceOfA is of type A
newWindow.instanceOfB = this.instanceOfA.listOfBObjects[0]; //instanceOfB is of type B
newWindow.Show();
}
}
public partial class SecondWindow : Window
{
internal A instanceOfA;
internal B instanceOfB;
public SecondWindow()
{
InitializeComponent();
Loaded += SecondWindow_Loaded;
}
void SecondWindow_Loaded(object sender, RoutedEventArgs e)
{
MessageBox
.Show(String.Format("{0}",
this.instanceOfB == this.instanceOfA.listOfBObjects[0]));
this.instanceOfB.three++;
this.instanceOfB.four--;
}
}
Note: this is not an answer, just trying to establish some common ground for further discussions, as comments don't leave you enough freedom for code samples.

Thanks to #pm_2 and #BillZhang comments, I found a row in my code in which this.currentPropertyToShowwas edited. After the returning back at first window, infact, I perform the refresh of the window, but it is not needed to edit this.currentPropertyToShow, so I have commented it and everything works!
Thanks everybody for precious comments and suggestions!

Use of 'this' in an event

I need to retrieve some property of an element that trigger the event in this context:
SoundEffect alarm;
public MainPage()
{
InitializeComponent();
Pad1.MouseLeftButtonUp += new MouseButtonEventHandler(makeasound);
Pad2.MouseLeftButtonUp += new MouseButtonEventHandler(makeasound);
Pad3.MouseLeftButtonUp += new MouseButtonEventHandler(makeasound);
}
Pad1,2 and 3 are the names of some Ellipse I have in my xaml. Now if I try to do this in the code executed by the event ( declared immediately after the sample code above):
private void makeasound(object sender, MouseButtonEventArgs e)
{
string text = this.Name;
textBlock1.Text = text;
}
The Text Block becomes empty, so I guess the Name of the triggering element never gets there.
Now, things get more messy if I'm trying to retrieve a custom property of the "pads" called "Son", declared with the dependency method , which is a string, like this:
private void makeasound(object sender, MouseButtonEventArgs e)
{
string text = this.Son;
textBlock1.Text = text;
}
VS reports error:
'PhoneApplication.MainPage' does not contain a definition for 'Son' and no extension method 'Son' accepting a first argument of type 'PhoneApplication.MainPage' could be found (are you missing a using directive or an assembly reference?)
Where Phoneapplication is the name of the app and the main namespace of the code behind.
As if it weren't simple enough, what I'm tryin to do is this:
The custom property is actually an INT. I know I declared the dependency right since VS let me compile. Each Pad has this custom property storing an int, and I need to retrieve it to access an array element. The function triggered is this:
private void makeasound(object sender, MouseButtonEventArgs e)
{
int x = this.Son;
var sons = new[] { "sons/firstsound.wav", "sons/secondsound.wav", "sons/thirdsound.wav" };
string target = sons[x];
StreamResourceInfo info = Application.GetResourceStream(
new Uri(target, UriKind.Relative));
alarm = SoundEffect.FromStream(info.Stream);
Microsoft.Xna.Framework.FrameworkDispatcher.Update();
alarm.Play();
}
So, I declare an array storing URI's for sounds that I'd like to play("son" means sound in french, I'm from Belgium). I then use the INT associated with the triggering element to access the URI of a sound, then I play this sound.
The reason I do this is because I'd like to let the user change the INT value for each pad and therefore choose what sound each pad plays. The fact that I seem to have no choice but to declare this array each time the function is called (otherwise it's not in context) is not very elegant but I guess I can live with that ( array will have 50-60 elements in it)
So, for those who read this far, my problem is to use a property of the triggering event, which seems to be harder when it's a custom property. I put the rest of the logic in case someone had advices.
I thank anyone who read this message and who could maybe help me sorting this out. I read online documentation and I have two good c# books, but I havent found a solution for me.
Have a nice day.
EDIT: Some others are willing to help so here is the declaration of the dependency property(Sorry Daniel, hadn't seen you commented my original post)
namespace MyNamespace
{
public static class MyClass
{
public static readonly DependencyProperty SonProperty = DependencyProperty.RegisterAttached("Son",
typeof(string), typeof(MyClass), new PropertyMetadata(null));
public static string GetSon(UIElement element)
{
if (element == null)
throw new ArgumentNullException("element");
return (string)element.GetValue(SonProperty);
}
public static void SetSon(UIElement element, string value)
{
if (element == null)
throw new ArgumentNullException("element");
element.SetValue(SonProperty, value);
}
}
Mynamespace is nested inside the main namespace.

this refers to the current instance of MainPage. Not to the pad that was clicked. That's the sender:
var pad = (Pad)sender;
var text = pad.Name;
textBlock1.Text = text;
Son is an attached property, not a normal one. You can get its value like this:
var pad = (Pad)sender;
var son = MyClass.GetSon(pad);
Please note that you have declared it as a string. Seeing how you want to use it, it seems to make more sense to declare it as an int.

this refers to the instance of the type in which the method is defined in, in this case, MainPage. If you want to get the instance of the type that triggered the event, that's what's in the sender parameter:
private void makeasound(object sender, MouseButtonEventArgs e)
{
textBlock1.Text = ((Pad)sender).Name;
}

C# make method required

I have a class with a method that when not called causes a crash.
Is there a way to make a compilation failure when the method isn't called?
Edit:
So what I have is basically a class that makes an istance of another class (a form) and it is a mesagebox with a do not show again option. Here's an example of how you'd use it.
public partial class Form1 : Form {
DontShowAgainBox box;
public void AlertYes() {
if (box.form.showagain.Checked)
t1.Text = "You chose yes (checked)!!!";
else
t1.Text = "You chose yes (unchecked)!!!";
}
public void AlertNo() {
if (box.form.showagain.Checked)
t1.Text = "You chose no (checked)!!!";
else
t1.Text = "You chose no (unchecked)!!!";
}
public Form1() {
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e) {
box = new DontShowAgainBox("Warning", "Are you sure?");
Action yesaction = new Action(AlertYes);
box.Bind_Yes(yesaction);
Action noaction = new Action(AlertNo);
box.Bind_No(noaction);
box.SetNoButton("Nope");
box.SetYesButton("I'm sure");
box.Show();
}
}
There's another method that you can hide the "No" button with also.
But the yes button is in every instance of the class so it needs to have a function associated with it or else... crash.

Why not just test for this in software instead of crashing?
if (!init_called) {
print error
exit
}

It is not possible for the compiler or linker to say, at build time, "Hey, this method that was supposed to be called wasn't called!" You can't make the compiler issue an error message because client code didn't call a particular method.
What you're asking is not possible.