I want to hide public methods from the IntelliSense member list. I have created an attribute that, when applied to a method, will cause the method to be called when its object is constructed. I've done this to better support partial classes. The problem is that in some environments (such as Silverlight), reflection cannot access private members, even those of child classes. This is a problem since all of the work is done in a base class. I have to make these methods public, but I want them to be hidden from IntelliSense, similar to how the Obsolete attribute works. Frankly, because I am anal about object encapsulation. I've tried different things, but nothing has actually worked. The method still shows up in the member drop-down.
How do I keep public methods from showing up in IntelliSense when I don't want them to be called by clients? How's that for a real question, Philistines! This can also apply to MEF properties that have to be public though sometimes you want to hide them from clients.
Update:
I have matured as a developer since I posted this question. Why I cared so much about hiding interface is beyond me.
Using the EditorBrowsable attribute like so will cause a method not to be shown in IntelliSense:
[System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)]
public void MyMethod()
{
}
You are looking for EditorBrowsableAttribute
The following sample demonstrates how to hide a property of a class from IntelliSense by setting the appropriate value for the EditorBrowsableAttribute attribute. Build Class1 in its own assembly.
In Visual Studio, create a new Windows Application solution, and add a reference to the assembly which contains Class1. In the Form1 constructor, declare an instance of Class1, type the name of the instance, and press the period key to activate the IntelliSense drop-down list of Class1 members. The Age property does not appear in the drop-down list.
using System;
using System.ComponentModel;
namespace EditorBrowsableDemo
{
public class Class1
{
public Class1()
{
//
// TODO: Add constructor logic here
//
}
int ageval;
[EditorBrowsable(EditorBrowsableState.Never)]
public int Age
{
get { return ageval; }
set
{
if (!ageval.Equals(value))
{
ageval = value;
}
}
}
}
}
To expand on my comment about partial methods. Try something like this
Foo.part1.cs
partial class Foo
{
public Foo()
{
Initialize();
}
partial void Initialize();
}
Foo.part2.cs
partial class Foo
{
partial void Initialize()
{
InitializePart1();
InitializePart2();
InitializePart3();
}
private void InitializePart1()
{
//logic goes here
}
private void InitializePart2()
{
//logic goes here
}
private void InitializePart3()
{
//logic goes here
}
}
Related
I have some code base which has is calling the following:
SetHazardDataService();
namespace Analytics.Foo.DataServices
{
class HDB:IDataService
{
}
}
With a member function declared in another class/file
using Analytics.Foo.DataServices
public void MyDataService()
{
var DbDataSvc = new HDB();
}
originally, I see the same definition used elsewhere but with (no idea if that works):
protected void MyDataService()
I included the public method in my class
I'm now trying to recreate that functionality, but I get the following issue:
The type Analytics.Foo.DataServices.HDB' has no constructors defined
I'm not sure what the issue is - any suggestions for why this is the case. There is no constructor that I can see. Plus I'm not able to see the other code working/but it doesn't give the same issue.
You need to create a constructor to class HDB, like this:
namespace Analytics.Foo.DataServices
{
class HDB:IDataService
{
public HDB()
{
}
}
}
I have two classes that I'd like to keep in separate files.
namespace GridSystem
{
public class Grid
{
public void AddItem(GridItem item)
{
item.InformAddedToGrid();
}
}
}
namespace GridSystem
{
public class GridItem
{
public void InformAddedToGrid()
{
Debug.Log("I've been added to the grid");
}
}
}
How do I ensure no other classes are allowed to call InformAddedToGrid?
I'm trying to emulate Actionscript namespaces, which can be used on a method, in place of public, private, internal, etc. It doesn't exactly protect the method, but forces an extra step of including the namespace before the method can be accessed. Is there an alternative approach to this in C#?
If GridItem itself can be hidden from the outside world as well I would consider putting GridItem inside Grid as a nested class. That way it won't be visible outside of the class
http://www.codeproject.com/Articles/20628/A-Tutorial-on-Nested-Classes-in-C
Not that you should do this, you should do what TGH suggests, have a public interface for GridItem, and have gridItem nested in Grid (then have a factory method on Grid to create Items and use partial Grid class to have them in separate files).
Because there isn't a way of having friend methods ( you can do friend classes through InternalsVisibleToAttribute )
You COULD do this ( but don't... )
public partial class Grid
{
public void AddItem(GridItem item)
{
item.InformAddedToGrid();
}
}
public class GridItem
{
public void InformAddedToGrid()
{
if (new StackTrace().GetFrame(1).GetMethod().DeclaringType !=
typeof(Grid)) throw new Exception("Tantrum!");
Console.WriteLine("Grid called in...");
}
}
then
var g = new Grid();
g.AddItem(new GridItem()); // works
new GridItem().InformAddedToGrid(); // throws a tantrum...
A really ugly answer would be to make it private and use reflection.
Another ugly answer would be to make it throw an exception if the caller is wrong.
Both of these are much slower to execute than a normal call also.
I don't think there's a good answer. C# doesn't have friends.
IMHO the answer is simple: access modifiers are just there to remind the programmer of the intent of how public/private a class should be. Through reflection you can lift those barriers.
The usage you make of a class is all in your hands: if your class is meant to only be used in one place, make it so. If anything, if a class has a special way of being used, document it - put it in the XML comments.
That said, in this specific example I'd believe since the GridItem doesn't add itself to the grid, it's not its job to notify about it (what if "I've not been added to the grid"?). I think InformAddedToGrid belongs somewhere in your Grid class as a private method, where there's a concept of adding an item... assuming that's what AddItem(GridItem) really does.
You can do it as TGH suggested, with nested classes, except the other way around. Nest Grid within GridItem and make InformAddedToGrid private. Here I use a nested base class so the public API can remain the same. Note that no one outside of your assembly can inherit from GridBase because the constructor is internal.
public class GridItem
{
public class GridBase
{
internal GridBase() { }
public void AddItem(GridItem item)
{
item.InformAddedToGrid();
}
}
private void InformAddedToGrid()
{
Debug.Log("I've been added to the grid");
}
}
public class Grid : GridItem.GridBase { }
Another option is to have GridItem explicitly implement an internal interface. This way no one outside of your assembly can use the interface by name and therefore cannot call InformAddedToGrid.
public class Grid
{
public void AddItem(GridItem item)
{
((IGridInformer)item).InformAddedToGrid();
}
}
public class GridItem : IGridInformer
{
void IGridInformer.InformAddedToGrid()
{
Debug.Log("I've been added to the grid");
}
}
internal interface IGridInformer
{
void InformAddedToGrid();
}
I am trying to use a method inside class, from another class.
namespace Crystal.Utilities
{
public class Logging
{
public static void Log()
{
//dostuff
Crystal.MainForm.general_log_add_item("Hello World");
}
}
}
namespace Crystal
{
public partial class MainForm : Form
{
public void general_log_add_item(string msg)
{
listBox1.Items.Add(msg);
}
}
}
I want to be able to call Crystal.Utilities.Logging.Log() from anywhere, and that to be able to call Crystal.MainForm.general_log_add_item() . But It doesn't let me, because if I put it as public, then I can't see it, if it's static then It can't interact with my listbox.
This is a wrong approach. Your class should not call into the UI, as the UI could change. The class should not know nor care about the UI. Instead, the class could expose an event that the form could subscribe to, and update based upon the information contained within the event's arguments.
Here's a hastily thrown together example.
class Program
{
static void Main()
{
Logger.OnLogging += Logger_OnLogging;
Logger.Log();
Logger.OnLogging -= Logger_OnLogging;
}
static void Logger_OnLogging(LoggingEventArgs e)
{
Trace.WriteLine(e.Message);
}
}
public class Logger
{
public delegate void LoggingEventHandler(LoggingEventArgs e);
public static event LoggingEventHandler OnLogging;
public static void Log()
{
// do stuff
RaiseLoggingEvent("Data logged");
}
protected static void RaiseLoggingEvent(string message)
{
if (OnLogging != null)
OnLogging(new LoggingEventArgs(message));
}
}
public class LoggingEventArgs : EventArgs
{
public LoggingEventArgs(string message)
{
this.Message = message;
}
public string Message { get; private set; }
}
Instead of implementing it as a static method, try implementing as a singleton. It's a common trick to make an instance global in scope, and restrict to one instance, without making everything static (and thus unable to be used as an instance).
You have to understand that the window is not static, there is one instance of him, thats why the method cant be static,
you can use
Application.Windows to reach this instance and call the add method.
or you can register the window in his constructor on another class that will mediate the Logging and the window.
If you don't understand tell me and I'll try to be more clear
When you declare a method as "static" you're saying that it's not dependent upon a specific instance of the class it's in.
For example if you have a class named "chair" and you want to count how many chairs there are, you'll do that with a static field, and a static method to return that field's value.
The count of all chairs is not related to a specific chair.
In your case you want to add a static method to add an item to a specific instance of a Form. That's impossible and doesn't make sense.
If you want to add an item to a listBox, it must be through a public method.
So basically what I'm saying is - rethink what you're trying to do, there's a good explanation as to why you're not succeeding in doing that.
I have some classes inherit from existing Windows Controls like TextBox and DateTimePicker, ..etc
I want to add custom functionalities for these classes like (Read, Alert, ...etc)
these added functionalities are the same in all these classes
The problem is: these classes inherited from difference parents so I can't put my added functionalities in the parent class,
What's the best practice in this case:
repeat the code in each inherited
class
Use a separated class have the
functionalities as Static Methods
with parameter from an interface, implement this interface for the classes and
then pass them.
Use a separated class like the second approach but with Dynamic parameter (which added in C# 4.0)
or other !!
Thanks in advance
I'd consider option 4: composition.
First, define your set of functionality. We'll assume that your partial list is exclusive, so "Read" and "Alert."
Second, create a single class that implements this functionality, something like MyCommonControlBehaviors. I'd prefer this implementation not be static if possible, though, it may be generic.
public MyCommonControlBehaviors
{
public Whatever Read() { /* ... */ }
public void Alert() {}
}
Third, use composition to add an instance of this class to each of your custom control types and expose that functionality through your custom control:
public class MyCustomControl
{
private MyCommonControlBehaviors common; // Composition
public Whatever Read() { return this.common.Read(); }
public void Alert() { this.common.Alert(); }
}
Depending on specifics, you can get creative to the degree necessary. E.g., perhaps your custom behaviors need to interact with private control data. In that case, make your control implement a common ICommonBehaviorHost interface that your common behaviors need. Then pass the control into the behavior class on construction as an instance of ICommonBehaviorHost:
public interface ICommonBehaviorHost
{
void Notify();
}
public class MyCommonControlBehaviors
{
ICommonBehaviorHost hst = null;
public MyCommonControlBehaviors(ICommonBehaviorHost host)
{
this.hst = host;
}
public void Alert() { this.hst.Notify(); } // Calls back into the hosting control
// ...
}
public class MyCustomControl : ICommonBehaviorHost
{
private MyCommonControlBehaviors common = null;
public MyCustomControl() { common = new MyCommonControlBehaviors(this); }
public Whatever Read() { return this.common.Read(); }
public void Alert() { this.common.Alert(); }
void ICommonBehaviorHost.Notify() { /* called by this.common */ }
}
Use Composition instead of Inheritence!
If you must, what I would probably do is create extension methods for each class and then reference the actual coded needed for these in some other object all the extension methods can call.
This way the code isn't duplicated, and the extension methods make it look like the methods should be in the object.
It's the same essentially by creating a static method and doing: Functions.DoSomething(my_Object);
But I always like: my_Object.DoSomething() better in an OO language.
I would suggest defining an interface for the behaviors, and then (to keep from repeating yourself) create extension methods on that interface definition for your shared methods. (Kinda like your second option, only with extension methods instead of totally static methods).
I have a constructor that is in generated code. I don't want to change the generated code (cause it would get overwritten when I regenerate), but I need to add some functionality to the constructor.
Here is some example code:
// Generated file
public partial class MyGeneratedClass
{
public MyGeneratedClass()
{
Does some generated stuff
}
}
The only solution I can come up with is this:
// My hand made file
public partial class MyGeneratedClass
{
public MyGeneratedClass(bool useOtherConstructor):this()
{
do my added functinallity
}
}
I am fairly sure this will work, but I then have a lame unused param to my constructors and I have to go change them all. Is there a better way? If not that is fine, but I thought I would ask.
If you're using C# 3 and can change the generator, you can use partial methods:
// MyGeneratedClass.Generated.cs
public partial class MyGeneratedClass
{
public MyGeneratedClass()
{
// Does some generated stuff
OnConstructorEnd();
}
partial void OnConstructorEnd();
}
// MyGeneratedClass.cs
public partial class MyGeneratedClass
{
partial void OnConstructorEnd()
{
// Do stuff here
}
}
Would your environment allow you to inherit from MyGeneratedClass rather than have it as a partial class. You could then override the constructor?
Assuming you can't change the generator output, unfortunately, your options are a bit limited, and not ideal considering what you're looking for. They are:
Inherit from the generated class. The child class will implicitly call the parent's construtor.
Use a static method as an initializer