7.13.3 Event assignment
If the left operand of a += or -= operator is classified as an event access, then the expression is evaluated as follows:
- The instance expression, if any, of the event access is evaluated.
- The right operand of the += or -= operator is evaluated, and, if required, converted to the type of the left operand through an implicit conversion (Section 6.1).
- An event accessor of the event is invoked, with the argument list consisting of the right operand, after evaluation and, if necessary, conversion. If the operator was +=, the
addaccessor is invoked. If the operator was -=, the
removeaccessor is invoked.
An event assignment expression does not yield a value. Thus, an event assignment expression is valid only in the context of a statement-expression (Section 8.6).