'@' symbol prefix on c# method call? [duplicate]

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W开发者_StackOverflow社区hat's the use/meaning of the @ character in variable names in C#?

I was doing some .net development and I noticed I could add an @ symbol before any method call, i.e.:

var message = dog.@SayHello();

Just wondering, why is the reason this can be done ??

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The @ symbol can escape keywords and turn them into ordinary identifiers. Most .net languages support a mechanism like this since keywords are language dependent, and thus code written in other languages might collide with a keyword in your language without even noticing it.

Some people like using @this for the first parameter extension methods.

public static void MyExtension(this MyType @this)

another scenario where this can be useful is when using members to represent html attributes. Then without this feature you could not represent the class attribute.

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An @ symbol can be pre-fixed to any identifier in case you're interoperating with code written in another language that uses C# keywords as identifiers:

object @class; //allowed
object class;  //error

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This is simply part of the definition of a valid identifier in C#.

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@ lets you use an identifier that would otherwise be interpreted as a keyword.

For example, if you want to have a variable named class, you can write this:

int @class;

Of course, because you can do it doesn't mean it's a good idea to do it.

Some situations where it's useful is code generators that create C# code from a template or external source. e.g. xsd.exe is an SDK command-line tool creates C# classes that back up an XML schema. If your XML schema contains an element or attribute name that is reserved in C# (such as class), xsd.exe would preserve the name in the matching C# class but it would prefix it with a @.

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It's a case of just because we can, doesn't mean we should.