C# Language Specification

This access

A this-access consists of the reserved word this.

this-access:
this

A this-access is permitted only in the block of an instance constructor, an instance method, or an instance accessor. It has one of the following meanings:

• 
  When this is used in a primary-expression within an instance constructor of a class, it is classified as a value. The type of the value is the instance type (§10.3.1) of the class within which the usage occurs, and the value is a reference to the object being constructed.
  
• 
  When this is used in a primary-expression within an instance method or instance accessor of a class, it is classified as a value. The type of the value is the instance type (§10.3.1) of the class within which the usage occurs, and the value is a reference to the object for which the method or accessor was invoked.
  
• 
  When this is used in a primary-expression within an instance constructor of a struct, it is classified as a variable. The type of the variable is the instance type (§10.3.1) of the struct within which the usage occurs, and the variable represents the struct being constructed. The this variable of an instance constructor of a struct behaves exactly the same as an out parameter of the struct type—in particular, this means that the variable must be definitely assigned in every execution path of the instance constructor.
  
• 
  When this is used in a primary-expression within an instance method or instance accessor of a struct, it is classified as a variable. The type of the variable is the instance type (§10.3.1) of the struct within which the usage occurs.
  

• 
  If the method or accessor is not an iterator (§10.14), the this variable represents the struct for which the method or accessor was invoked, and behaves exactly the same as a ref parameter of the struct type.
  
• 
  If the method or accessor is an iterator, the this variable represents a copy of the struct for which the method or accessor was invoked, and behaves exactly the same as a value parameter of the struct type.
  

Use of this in a primary-expression in a context other than the ones listed above is a compile-time error. In particular, it is not possible to refer to this in a static method, a static property accessor, or in a variable-initializer of a field declaration.

8.