I want to create an alias for a class name. The following syntax would be perfect:
public class LongClassNameOrOneThatContainsVersionsOrDomainSpecificName
{
...
}
public class MyName = LongClassNameOrOneThatContainsVersionOrDomainSpecificName;
but it won't compile.
Example
Note This example is provided for convenience only. Don't try to solve this particular problem by suggesting changing the design of the entire system. The presence, or lack, of this example doesn't change the original question.
Some existing code depends on the presence of a static class:
public static class ColorScheme
{
...
}
This color scheme is the Outlook 2003 color scheme. i want to introduce an Outlook 2007 color scheme, while retaining the Outlook 2003 color scheme:
public static class Outlook2003ColorScheme
{
...
}
public static class Outlook2007ColorScheme
{
...
}
But i'm still faced with the fact that the code depends on the presence of a static class called ColorScheme. My first thought was to create a ColorScheme class that I will inherit from either Outlook2003 or Outlook2007:
public static class ColorScheme : Outlook2007ColorScheme
{
}
but you cannot inherit from a static class.
My next thought was to create the static ColorScheme class, but make Outlook2003ColorScheme and Outlook2007ColorScheme classes non-static. Then a static variable in the static ColorScheme class can point to either "true" color scheme:
public static class ColorScheme
{
private static CustomColorScheme = new Outlook2007ColorScheme();
...
}
private class CustomColorScheme
{
...
}
private class Outlook2008ColorScheme : CustomColorScheme
{
...
}
private class Outlook2003ColorScheme : CustomColorScheme
{
...
}
but that would require me to convert a class composed entirly of readonly static Colors into overridable properties, and then my ColorScheme class would need to have the 30 different property getters thunk down into the contained object.
That's just too much typing.
So my next thought was to alias the class:
public static ColorScheme = Outlook2007ColorScheme;
But that doesn't compile.
How can I alias a static class into another name?
Update: Can someone please add the answer "You cannot do this in C#", so I can mark that as the accepted answer. Anyone else wanting the answer to the same question will find this question, the accepted answer, and a number of workarounds that might, or might not, be useful.
I just want to close this question out.
You can’t. The next best thing you can do is have using declarations in the files that use the class.
For example, you could rewrite the dependent code using an import alias (as a quasi-typedef substitute):
using ColorScheme = The.Fully.Qualified.Namespace.Outlook2007ColorScheme;
Unfortunately this needs to go into every scope/file that uses the name.
I therefore don't know if this is practical in your case.
You can make an alias for your class by adding this line of code:
using Outlook2007ColorScheme = YourNameSpace.ColorScheme;
You cannot alias a class name in C#.
There are things you can do that are not aliasing a class name in C#.
But to answer the original question: you cannot alias a class name in C#.
Update: People are confused why using doesn't work. Example:
Form1.cs
private void button1_Click(object sender, EventArgs e)
{
this.BackColor = ColorScheme.ApplyColorScheme(this.BackColor);
}
ColorScheme.cs
class ColorScheme
{
public static Color ApplyColorScheme(Color c) { ... }
}
And everything works. Now i want to create a new class, and alias ColorScheme to it (so that no code needs to be modified):
ColorScheme.cs
using ColorScheme = Outlook2007ColorScheme;
class Outlook2007ColorScheme
{
public static Color ApplyColorScheme(Color c) { ... }
}
Ohh, i'm sorry. This code doesn't compile:
My question was how to alias a class in C#. It cannot be done. There are things i can do that are not aliasing a class name in C#:
change everyone who depends on ColorScheme to using ColorScheme instead (code change workaround because i cannot alias)
change everyone who depends on ColorScheme to use a factory pattern them a polymorphic class or interface (code change workaround because i cannot alias)
But these workarounds involve breaking existing code: not an option.
If people depend on the presence of a ColorScheme class, i have to actually copy/paste a ColorScheme class.
In other words: i cannot alias a class name in C#.
This contrasts with other object oriented languages, where i could define the alias:
ColorScheme = Outlook2007ColorScheme
and i'd be done.
You want a (Factory|Singleton), depending on your requirements. The premise is to make it so that the client code doesn't have to know which color scheme it is getting. If the color scheme should be application wide, a singleton should be fine. If you may use a different scheme in different circumstances, a Factory pattern is probably the way to go. Either way, when the color scheme needs to change, the code only has to be changed in one place.
public interface ColorScheme {
Color TitleBar { get; }
Color Background{ get; }
...
}
public static class ColorSchemeFactory {
private static ColorScheme scheme = new Outlook2007ColorScheme();
public static ColorScheme GetColorScheme() { //Add applicable arguments
return scheme;
}
}
public class Outlook2003ColorScheme: ColorScheme {
public Color TitleBar {
get { return Color.LightBlue; }
}
public Color Background {
get { return Color.Gray; }
}
}
public class Outlook2007ColorScheme: ColorScheme {
public Color TitleBar {
get { return Color.Blue; }
}
public Color Background {
get { return Color.White; }
}
}
try this:
using ColorScheme=[fully qualified].Outlook2007ColorScheme
I'm adding this comment for users finding this long after OP accepted their "answer".
Aliasing in C# works by specifying the class name using it's fully qualified namespace. One defined, the alias name can be used within it's scope.
Example.
using aliasClass = Fully.Qualified.Namespace.Example;
//Example being the class in the Fully.Qualified.Namespace
public class Test{
public void Test_Function(){
aliasClass.DoStuff();
//aliasClass here representing the Example class thus aliasing
//aliasClass will be in scope for all code in my Test.cs file
}
}
Apologies for the quickly typed code but hopefully it explains how this should be implemented so that users aren't mislead into believing it cannot be done in C#.
Aliasing the way that you would like to do it will not work in C#. This is because aliasing is done through the using directive, which is limited to the file/namespace in question. If you have 50 files that use the old class name, that will mean 50 places to update.
That said, I think there is an easy solution to make your code change as minimal as possible. Make the ColorScheme class a facade for your calls to the actual classes with the implementation, and use the using in that file to determine which ColorScheme you use.
In other words, do this:
using CurrentColorScheme = Outlook2007ColorScheme;
public static class ColorScheme
{
public static Color ApplyColorScheme(Color c)
{
return CurrentColorScheme.ApplyColorScheme(c);
}
public static Something DoSomethingElse(Param a, Param b)
{
return CurrentColorScheme.DoSomethingElse(a, b);
}
}
Then in your code behind, change nothing:
private void button1_Click(object sender, EventArgs e)
{
this.BackColor = ColorScheme.ApplyColorScheme(this.BackColor);
}
You can then update the values of ColorScheme by updating one line of code (using CurrentColorScheme = Outlook2008ColorScheme;).
A couple concerns here:
Every new method or property definition will then need to be added in two places, to the ColorScheme class and to the Outlook2007ColorScheme class. This is extra work, but if this is true legacy code, it shouldn't be a frequent occurence. As a bonus, the code in ColorScheme is so simple that any possible bug is very obvious.
This use of static classes doesn't seem natural to me; I probably would try to refactor the legacy code to do this differently, but I understand too that your situation may not allow that.
If you already have a ColorScheme class that you're replacing, this approach and any other could be a problem. I would advise that you rename that class to something like ColorSchemeOld, and then access it through using CurrentColorScheme = ColorSchemeOld;.
I suppose you can always inherit from the base class with nothing added
public class Child : MyReallyReallyLongNamedClass {}
UPDATE
But if you have the capability of refactoring the class itself: A class name is usually unnecessarily long due to lack of namespaces.
If you see cases as ApiLoginUser, DataBaseUser, WebPortalLoginUser, is usually indication of lack of namespace due the fear that the name User might conflict.
In this case however, you can use namespace alias ,as it has been pointed out in above posts
using LoginApi = MyCompany.Api.Login;
using AuthDB = MyCompany.DataBase.Auth;
using ViewModels = MyCompany.BananasPortal.Models;
// ...
AuthDB.User dbUser;
using ( var ctxt = new AuthDB.AuthContext() )
{
dbUser = ctxt.Users.Find(userId);
}
var apiUser = new LoginApi.Models.User {
Username = dbUser.EmailAddess,
Password = "*****"
};
LoginApi.UserSession apiUserSession = await LoginApi.Login(apiUser);
var vm = new ViewModels.User(apiUserSession.User.Details);
return View(vm);
Note how the class names are all User, but in different namespaces. Quoting PEP-20: Zen of Python:
Namespaces are one honking great idea -- let's do more of those!
Hope this helps
Is it possible to change to using an interface?
Perhaps you could create an IColorScheme interface that all of the classes implement?
This would work well with the factory pattern as shown by Chris Marasti-Georg
It's a very late partial answer - but if you define the same class 'ColorScheme', in the same namespace 'Outlook', but in separate assemblies, one called Outlook2003 and the other Outlook2007, then all you need to do is reference the appropriate assembly.
The best way I've found to simulate alias in C# is inheritance.
Create a new class that inherits from the original class:
public class LongClassNameOrOneThatContainsVersionsOrDomainSpecificName
{
...
}
public class MyName
: LongClassNameOrOneThatContainsVersionOrDomainSpecificName
{
}
The only thing that you would need to be careful is the constructor. You need to provide a a constructor for MyName class.
public class MyName
: LongClassNameOrOneThatContainsVersionOrDomainSpecificName
{
public MyName(T1 param1, T2 param2) : base(param1, param2) {}
}
In this example I'm using T1 and T2 as generic types, since I don't know the constructor for your LongClassNameOrOneThatContainsVersionOrDomainSpecificName class.
Beware, though, that this is not alias. Doing this to you application might run into some issues or problems. You might need to create some extra code to check for types, or even overload some operators.
In C++ I can declare a fully functional anonymous class inside a piece of code where it's needed so that I don't have to declare it if I need it only once.
The code should be like this
Class MyClass
{
Class
{
String string1;
String string2;
void MyMethod();
} Strings;
}
And call it the members with MyClass.Strings.string1, MyClass.Strings.MyMethod() and so on. This way I can elegantly group my code.
Is there a way to do the same thing in C#?
This way I can elegantly group my code.
I don't how can this help you to elegantly group your code, but there is no such thing in C#. There are anonymous classes but they only work in local scopes:
// inside a method:
var obj = new { String1 = "Hello", String2 = "World" };
And you can't add methods to them.
The closest thing you can get to is an inner class/struct:
class MyClass
{
class MyStrings
{
String string1;
String string2;
void MyMethod() { ... }
}
MyStrings Strings;
}
I agree Sweeper. This functionality adds just cluttering code. You should consider to make your code as easy as possible to understand. This means if you feal that you want to group your code, giving every group it´s own functionality, why not make this group a class and give it a name that directly reflects what its purpose is.
What you can do is use an anonymous class which in C# doesn´t implement any interface but just derives from object:
var a = new { MyMember = 1, MyFunc = new Func<int>(() => 1) };
now you can invoke both members of this type:
Console.WriteLine(a.MyMember);
var retVal = a.myFunc();
But does this make your code any better in a way that it´s easier to understand what it does? I doubt so. Give your instances - even when used only once - a name that describes what their intention - the idea behind - is. Don´t make it hard for others to understand your code by cryptifying it.
Apart from this you can restrict the use of your class to be private by nesting it within another one:
public class MyClass
{
private class Strings { /* ... */ }
}
Now your class is just visible to itself and within MyClass (and in other classes that are nested in MyClass of course). This makes it impossible to access the class from the outside like so:
var strings = new MyClass.Strings();
Try making the inner class static. That way you will be able to use the syntax you describe:
class MyClass {
public static Strings {
public static string string1;
public static string string2;
public static void MyMethod() {}
}
}
You can then call: MyClass.Strings.string1 = "Hell, world!";
example:
class document
{
public void new()
{
}
public void save()
{
}
}
visual studio claim that new is red-underlined with error.
I need that all is lower-cased to arrange cleanliness
For those seen this Questions:*
**(Answer)C# Naming rule violation: Words must be begin with Upper Cases!!!
NO, you can't since new is a keywoard. But, YES, you can escape keywords by # if accepted.
class document
{
public void test()
{
this.#new();
}
public void #new()
{
Console.WriteLine();
}
}
C# suggests using upper camel case in class name and method name.
Since keywords are in lower cases, upper camel case names, like void New(), are unaffected.
No you cannot use keywords as identifiers. See article https://msdn.microsoft.com/en-us/library/x53a06bb.aspx.
I have a bunch of code that is used for debugging purposes. Therefore, I surround it with:
#if DEBUG
#endif
The issue is that this debugging code needs to output private variables from other classes to a file. I can sneak the debug code into each class but that makes existing code more confusing because I have debug code mixed with real code. I can put all the debug code into another class but that would mean that I would have to make private variables in classes public.
Is there any way to ignore the private keyword for the purposes of debugging code? I can use public getters but that defeats the purpose of not making the real code more confusing.
Is it possible to make them internal instead of private?
Use the dynamic keyword:
dynamic foo = yourObjectWithPrivateFields;
int privateValue = (int)foo.yourPrivateField;
Use Reflection: typeof(YourObject).GetField(fieldName, bindFlags).GetValue(yourObjectWithPrivateFields);
Using Reflection as thefiloe suggests might be the best way to go for this particular problem.
Just to illustrate one way to address the code organization problem that the OP asked about, I've provided an example of an alternate approach. This may not be the ideal way to solve the problem of wanting to log data from private members for debugging purposes, but it demonstrates organizing code using partial classes as well as using a nested class in order to provide external code with a way to access private members.
// This MyClass code goes into a MyClass.cs file
public partial class MyClass
{
private int fieldA;
private string fieldB;
private decimal fieldC;
public MyClass(int a, string b, decimal c)
{
this.fieldA = a;
this.fieldB = b;
this.fieldC = c;
}
}
// This additional code for MyClass goes into a
// separate MyClass.debug.cs file
#if DEBUG
partial class MyClass : IDebugAccessible
{
public IDebugAccessor GetDebugAccessor()
{
return new DebugAccessor(this);
}
// The MyClass.DebugAccessor nested class has access to
// private members of MyClass.
private class DebugAccessor : IDebugAccessor
{
private MyClass instance;
public DebugAccessor(MyClass instance)
{
this.instance = instance;
}
public IEnumerable<KeyValuePair<string, object>> Values
{
get
{
return new Dictionary<string, object>
{
{ "fieldA", instance.fieldA },
{ "fieldB", instance.fieldB },
{ "fieldC", instance.fieldC },
};
}
}
}
}
#endif
// The intention behind creating these interfaces is to define
// a standard way to access values from different types
// for debugging purposes. This is just a simple example.
// These interfaces would go into their own .cs file.
public interface IDebugAccessor
{
IEnumerable<KeyValuePair<string, object>> Values { get; }
}
public interface IDebugAccessible
{
IDebugAccessor GetDebugAccessor();
}
Trying to do everything by the book, is this correct?:
public class JollyHockey
{
public string AnotherCoolProperty { get { return anotherCoolProperty; } }
string anotherCoolProperty;
public JollyHockey(string anotherCoolProperty)
{
this.anotherCoolProperty = anotherCoolProperty;
}
}
Or do some people use underscores for the private class variables?
Some people (including myself) prefix private class variables with an underscore (simply as a visual indication of what is being used where).
This is mainly a personal (or team) level style consideration and you can use what you want (or what your team has standardized on).
Just be sure you're consistent!
For what it's worth, you could also use auto-properties for your example:
public class JollyHockey
{
public string AnotherCoolProperty { get; private set; }
public JollyHockey(string anotherCoolProperty)
{
AnotherCoolProperty = anotherCoolProperty;
}
}
Or you can do this:
public class JollyHockey
{
public string AnotherCoolProperty { get; private set; }
public JollyHockey(string anotherCoolProperty)
{
this.AnotherCoolProperty = anotherCoolProperty;
}
}
I believe that your example agrees with the MS coding guidelines. However, I don't like it, and this is something that can be agreed upon by your team.
The reason I don't like it is because the underlying field name often conflicts with method parameters. I use an underscore to make it clear that they are private variables.
When a function parameter has the same name as a private field,
I usually prefix the parameter with an underscore
I think it makes sense
the ReSharper thing By fletcher is a good idea