Re-raising Exceptions When the reserved word raise occurs in an exception block without an object reference following it, it raises whatever
exception is handled by the block. This allows an exception handler to respond to an error in a limited way and then
re-raise the exception. Re-raising is useful when a procedure or function has to clean up after an exception occurs
but cannot fully handle the exception.
For example, the
GetFileList
function allocates a
TStringList
object and fills it with file names matching a
specified search path:
function GetFileList(const Path: string): TStringList;
var
I: Integer;
SearchRec: TSearchRec;
begin
Result := TStringList.Create;
try
I := FindFirst(Path, 0, SearchRec);
while I = 0 do
begin
Result.Add(SearchRec.Name);
I := FindNext(SearchRec);
end;
except
Result.Free;
raise;
end;
end;
GetFileList
creates a
TStringList
object, then uses the
FindFirst
and
FindNext
functions (defined in
SysUtils
) to initialize it. If the initialization fails - for example because the search path is invalid, or because there
is not enough memory to fill in the string list -
GetFileList
needs to dispose of the new string list, since the caller
does not yet know of its existence. For this reason, initialization of the string list is performed in a
try...except
statement. If an exception occurs, the statement's exception block disposes of the string list, then re-raises the
exception.
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