Values of expressions

Most of the constructs that involve an expression ultimately require the expression to denote a value. In such cases, if the actual expression denotes a namespace, a type, a method group, or nothing, a compile-time error occurs. However, if the expression denotes a property access, an indexer access, or a variable, the value of the property, indexer, or variable is implicitly substituted: The value of a variable is simply the value currently stored in the storage location identified by the variable. A variable must be considered definitely assigned (12.3) before its value can be obtained, or otherwise a compile-time error occurs. The value of a property access expression is obtained by invoking the get-accessor of the property. If the property has no get-accessor, a compile-time error occurs. Otherwise, a function member invocation (14.4.3) is performed, and the result of the invocation becomes the value of the property access expression. The value of an indexer access expression is obtained by invoking the get-accessor of the indexer. If the indexer has no get-accessor, a compile-time error occurs. Otherwise, a function member invocation (14.4.3) is performed with the argument list associated with the indexer access expression, and the result of the invocation becomes the value of the indexer access expression.