How to Alias a Class Name in C#, Without Having to Add a Line of Code to Every File That Uses the Class

How do I alias a class name in C#, without having to add a line of code to every file that uses the class?

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#.

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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.

C#: How to create aliases for classes

Use a using directive

using Rppr = Namespace.To.RelocatedPlantProductReleaseItem;

EDIT Op clarified to ask for a global solution.

There is no typedef style equivalent in C# which can create a global replacement of a type name. You'll need to use a using directive in every file you want to have this abbreviation or go for the long version of the name.

Techniques for aliasing in C#?

You can use using like so: using Currency = System.Single;, but you must do it in every single file. But still easier to change, than searching for single in whole application.

How do I reference a Using Alias Directive from another class/file

No, you can't do this:

using directive (C# Reference)

The scope of a using directive is limited to the file in which it
appears.

Further clarification in:

Namespaces - C# language specifications

Given

namespace N3
{
    using R = N1.N2;
}

namespace N3
{
    class B: R.A {}            // Error, R unknown
}

the scope of the using_alias_directive that introduces R only extends
to member declarations in the namespace body in which it is contained,
so R is unknown in the second namespace declaration.

In short, they are only valid in the enclosing compilation unit or immediate namespace they are declared, and are limited to the file they exist in.

Can I 'rename' an external exception class?

Possible duplicate of How do I alias a class name in C#?

In the usings...

using CustomerOverCreditLimitException = The.Fully.Qualified.Namespace.Ex20301Exception;

C# paste T model class dynamically as variable

It depends what you mean by "dynamic".

If you just don't want to use the class name "Students", then you're looking for a Type Alias.

using dynamicType = MyNameSpace.Student;

...
IEnumerable<dynamicType> students = GetAllStudents();

If you want to be able to specify which type you're dealing with from another part of code, you're looking for Generics.

void DoSomething<T>()
{
    IEnumerable<T> things = GetAllThings<T>();
    ...
}

...
DoSomething<Student>();

If you want to be able to interact with the class without having any specific type associated with it, you're looking for the dynamic keyword.

IEnumerable<dynamic> students = GetAllStudents();
foreach(var student in students)
{
    dynamic studentFoo = student.foo; // no type checking
}

If you want to avoid typing "Student" everywhere, but you really do want the items in your IEnumerable to be statically-checked Students, then you may just want to use the var keyword.\

var students = GetAllStudents();

How to define a class in C#

I guess you don't mean class, instead you can use a "Using Alias Directive". The syntax for this is as follows:

using PointCloud = System.Collections.Generic.List<PointData>;

Is it possible to declare an alias with .net type?

For example:

using MatchBuilderFactoryFunc = System.Func<
    IndexerBase.RequestMatching.RequestFreeTextAnalyzeParameter,
    System.Collections.Generic.IEnumerable<
        IndexerBase.RequestMatching.IMatchBuilder>>;

And after all use it as simple type:

MatchBuilderFactoryFunc f = ...

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