I'm sure this has been asked before I just don't know the correct way to word it so I can't find what I am looking for.
I have a class with a field which I want to be able to see from the outside, just not be able to modify it directly..
public class myclass
{
public int value;
public void add1()
{
value = value + 1;
}
}
So I would really like to only have the 'value' field modifiable from the method add1() but I still want to be able to see the value of 'value'.
EDIT: I was thinking only modifiable via the class myclass, but I typed otherwise. Thanks for pointing that out.
public int value { get; private set; }
You cannot make it modifiable only by the method add1, but you can make it only modifiable by myclass.
See this:
https://msdn.microsoft.com/en-us/library/75e8y5dd.aspx
Please consider the following options to encapsulate a field (i.e. provide an "interface" for the private field value):
Provide the public method (accessor):
// ...
private value;
// ...
public void Add()
{
++value;
}
public int GetValue()
{
return value;
}
Provide the public property (only accessor):
// ...
private value;
// ...
public void Add()
{
++value;
}
public int Value
{
get { return value; }
}
Provide the auto-implemented property (public accessor, private mutator):
// ...
// The field itself is not needed: private value;
// ...
public void Add()
{
++Value;
}
public int Value { get; private set; }
It is worth noting that some IDEs or IDE–plugins provide the appropriate refactoring called "Encapsulate Field".
You can use public property without setter to just see the value from outside. make the value private so its only visible inside the calss.
public class myclass
{
private int value;
public void add1()
{
value = value + 1;
}
public int Value
{
get
{
return value;
}
}
}
Related
I want to get value of TextBox in Form1, to another class.
I try to make a set and get, but I can't do this, because VS shows me error about ambiguity in code.
public partial class Form1 : Form
{
private TextBox _textBox1;
public Form1()
{
this._textBox1 = textBox1;
InitializeComponent();
}
public string _textBox1
{
get { return _textBox1.Text; }
set { _textBox1.Text = value; }
}
}
How to make this correct? My control is private.
You have one field and one property in you class with the same name, change the name of the property, for instance to
public string FormTextBox1
{
get { return _textBox1.Text; }
set { _textBox1.Text = value; }
}
as naming standard the public properties must be Pascal Case notation
Capitalization Conventions
You can pass textBox1.Text to a variable, and make a getter/setter for it.
Like this:
public class A : Form1
{
// assuming it's a string. If it's not, change the type
// for the getter method below accordingly
private string textBoxValue;
// at some point, you'll have to make this line below:
textBoxValue = textBox1.Value;
public string GetTextBoxValue()
{
return textBoxValue;
}
}
public class B
{
A aReference = new A();
// you can get the value you want by doing
// aReference.GetTextBoxValue();
}
public void yourFormLoadMethod()
{
//this instantiates a new object of your class
nameOfYourClass newYourObject = new nameOfYourClass(//put any params you need here);
txtNameOfYourTextBox.DataBindings.Add("Enabled", newLTDObjectBenInt, "YourTextBoxEnabled", true, DataSourceUpdateMode.OnPropertyChanged);
txtNameOfYourTextBox.DataBindings.Add("Value", newLTDObjectBenInt, "YourTextBoxEntered", true, DataSourceUpdateMode.OnPropertyChanged);
txtNameOfYourTextBox.DataBindings.Add("Visible", newLTDObjectBenInt, "YourTextBoxVisible", true, DataSourceUpdateMode.OnPropertyChanged);
}
public class nameOfYourClass
{
//constructor
public nameOfYourClass(//same params here from the Load method)
{
//place any logic that you need here to load your class properly
//this sets default values for Enable, Visible and the text
//you use these fields to manipulate your field as you wish
yourTextBoxVisible = true;
yourTextBoxEnabled = true;
yourTextBoxEntered = "this is the default text in my textbox";
}
private bool yourTextBoxEnabled;
public bool YourTextBoxEnabled
{
get
{
return yourTextBoxEnabled;
}
set
{
yourTextBoxEnabled = value;
}
}
private bool yourTextBoxVisible;
public bool YourTextBoxVisible
{
get
{
return yourTextBoxVisible;
}
set
{
yourTextBoxVisible = value;
}
}
private string yourTextBoxEntered;
public string YourTextBoxEntered
{
get
{
return yourTextBoxEntered;
}
set
{
yourTextBoxEntered = value;
}
}
}
I get this error on the setter line
"An unhandled exception of type 'System.StackOverflowException' occurred in WebFormsApplication1.dll"
What is an elegant way to manipulate Property1 which I added getter and setter for in a Master page (please see below),
then I attempted to manipulate it in method1() and finally call method1() inside onInit.
namespace WebFormsApplication1
{
public partial class SiteMaster : MasterPage
{
public string Property1
{
get
{
return System.Configuration.ConfigurationSettings.AppSettings["key1"];
//gets value from config file where pair key-value is stored
}
set
{
Property1 = value;
}
}
public void method1()
{
Property1 = Property1 + "stringToAppend"; // manipulate property here
}
protected void Page_Init(object sender, EventArgs e)
{
method1();
.....
}
}
}
In the Site.Master.aspx I have <%= Property1 %>
If I don't add the setter the property is read only. Maybe I should manipulate it inside the setter?
I was hoping to be able to do it separately for increased modularisation.
Thanks
the problem is here:
set
{
Property1 = value;
}
You can't do it because recursion occurs here and no condition to exit, you can't set this property in his own setter, you should have some field and set it in setter:
public string someValue = System.Configuration.ConfigurationSettings.AppSettings["key1"];
public string Property1
{
get
{
return someValue;
}
set
{
someValue = value;
}
}
Or you can use auto-property:
C# 6:
public string Property1 {get;set;} = System.Configuration.ConfigurationSettings.AppSettings["key1"];
Or lower than C# 6 - you should declare you property and initialize it in contructor or method:
public string Property1 {get;set;}
public void ConstructorOrMethod()
{
Property1 = System.Configuration.ConfigurationSettings.AppSettings["key1"];
}
I have a class that contains two other objects.
A variable in the first object bind to WPF element, call it X.
A similar variable in the other object.
I want that when the PropertyChanged event happens, it will change the variable in the second object.
Here is the code that does not work for me:
The class that contains the variables: (I had register to property changed event)
private Class1 _var1;
public Class1 Var1
{
get { return _var1; }
set
{
_var1= value;
if (_var1!= null)
_var1.PropertyChanged += new PropertyChangedEventHandler(_var1_PropertyChanged);
else
_var1.PropertyChanged -= new PropertyChangedEventHandler(_var1_PropertyChanged);
}
}
void _var1_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
if(e.PropertyName=="X")
Var2.X= Var1.X;
}
private Class2 _var2;
public Class2 Var2
{
get { return _var2; }
set { _var2= value; }
}
Class 1:
private int _x;
public int X
{
get { return _x; }
set
{
if (_x!= value)
{
_x= value;
NotifyPropertyChanged("X");
}
}
}
class 2:
public int X { get; set; }
PropertyChanged work in class 1 but he did not come to an event I created in a class that contains the two variables, why?
I'm not sure I understand exactly what you mean, but if I had a class with 2 variables that I wanted to change together, I would try the following:
First, define some SetAndNotify method or you'll get a headache from the PropertyChanged events:
public void SetAndNotify<T>(ref T field, T value, Expression<Func<T>> exp)
{
if (!Equals(field, value))
{
field = value;
OnPropertyChanged(exp);
}
}
Add it to some base class that will handle this event.
Second, in your setter for Var1 you register for the change event and not set anything, is that on purpose?
Third and last, there's no problem with changing more than one property in a setter, but make sure it's the public property that you change:
private SomeType privateVar1;
public SomeType PublicVar1
{
get { return privateVar1; }
set
{
SetAndNotify(ref privateVar1, value, () => PublicVar1);
MyOtherPublicVar = someNewValue; // this will activate the property's setter.
}
}
I hope this helps. If not, please try to clarify your question.
This is essentially what I want to do:
public abstract class Uniform<T>
{
public readonly int Location;
private T _variable;
public virtual T Variable
{
get { return _variable; }
}
}
public class UniformMatrix4 : Uniform<Matrix4>
{
public override Matrix4 Variable
{
set
{
_variable = value;
GL.UniformMatrix4(Location, false, ref _variable);
}
}
}
The getter for Variable will be the same across all derived classes, but the setter needs to be different.
In fact... I'd prefer not to have derived classes at all (it's only one function call that will differ for each type) but I can't think of how else to do it.
Edit: If it wasn't clear what the problem I'm having is, I'm getting a syntax error:
'UniformMatrix4.Variable.set': cannot override because 'Uniform.Variable' does not have an overridable set accessor
And I'm not sure how to create an "overridable set accessor"... virtual and abstract don't seem to be allowed on the setter.
It's not possible to do this in C#, but as a workaround you could do this. It would involve calling an abstract setter function which could be overridden by derived classes, while leaving the standard get intact. Would this work?
public abstract class Uniform<T>
{
public readonly int Location;
protected T _variable;
public T Variable
{
get { return _variable; }
set { SetVariable(value); }
}
protected abstract void SetVariable(T value);
}
public class UniformMatrix4 : Uniform<Matrix4>
{
public override void SetVariable(Matrix4x4 value)
{
_variable = value;
GL.UniformMatrix4(Location, false, ref _variable);
}
}
You will need to do this:
public abstract class Uniform<T>
{
public readonly int Location;
public virtual T Variable
{
get; set;
}
}
public class UniformMatrix4 : Uniform<Matrix4>
{
public override Matrix4 Variable
{
get
{
return base.Variable;
}
set
{
base.Variable = value;
GL.UniformMatrix4(Location, false, ref value);
}
}
}
As I understand, the behaviour will be the expected.
Hope it helps.
It is not possible to do this in C#. You have to add a setter to the base class, and make it throw an "Invalid Operation" exception.
I've defined a class with the following property:
private ObservableCollection<Job> allJobs;
Access is defined as follows:
public ObservableCollection<Job> AllJobs
{
get
{
return this.allJobs;
}
set
{
this.allJobs = value;
}
}
The get set works fine when I assign a whole ObservableCollection to the property, the set works fine for retrieving it obviously. But why have I lost all the methods that normally allow me to 'Add' (i.e. add 1 job to the collection)?
At the moment I'm having to create a temporary collection to populate to then assign to the allJobs property and I shouldn't have to.
Any ideas??
What do you mean with 'lost methods'? Have you tried AllJobs.Add()? The following code works for me:
void Main()
{
AllJobs = new ObservableCollection<Job>();
AllJobs.Add(new Job());
}
public class Job { }
private ObservableCollection<Job> allJobs;
public ObservableCollection<Job> AllJobs
{
get
{
return this.allJobs;
}
set
{
this.allJobs = value;
}
}
EDIT:
Based on your comment I've amended my code as follows but everything still works for me, I have noticed however that you don't seen to initialise the allJobs collection anywhere.
void Main()
{
PresentationManager.Instance.AllJobs.Add(new Job());
}
public class Job { }
sealed class PresentationManager
{
public static readonly PresentationManager Instance = new PresentationManager();
private PresentationManager()
{
allJobs = new ObservableCollection<Job>();
}
private ObservableCollection<Job> allJobs;
public ObservableCollection<Job> AllJobs
{
get { return this.allJobs; }
set { this.allJobs = value; }
}
}
Normally you wouldn't want a setter for such a property, as you would lose all events bound to the ObservableCollection when the setter is used.
public ObservableCollection<Job> AllJobs { get; private set; }