13.1 The raise statement

The raise statement is as follows:

_________________________________________________________________________________________________________ Raise statement
-- --raise statement-------------------------------------------------
-exception instance-|---------------------|
|-at-address expression-|
___________________________________________________________________

This statement will raise an exception. If it is specied, the exception instance must be an initialized instance of a class, which is the raise type. The address exception is optional. If itis not specied, the compiler will provide the address by itself. If the exception instance is omitted, then the current exception is re-raised. This construct can only be used in an exception handling block (see further).

Remark: Control never returns after an exception block. The control is transferred to the rst try...finally or try...except statement that is encountered when unwinding the stack. If no such statement is found, the Free Pascal Run-Time Library will generate a run-time error 217 (see also section 13.5, page 457).

As an example: The following division checks whether the denominator is zero, and if so, raises an exception of type EDivException

Type EDivException = Class(Exception);
Function DoDiv (X,Y : Longint) : Integer;
begin
  If Y=0 then
    Raise EDivException.Create ('Division by Zero would occur');
  Result := X Div Y;
end;

The class Exception is dened in the Sysutils unit of the rtl. (section 13.5, page 457)

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