On 1/24/25 4:04 AM, Hairy Pixels via fpc-pascal wrote:
On Jan 24, 2025 at 8:38:25 AM, Nikolay Nikolov via fpc-pascal
<fpc-pascal@lists.freepascal.org> wrote:
Maybe because there's a much better way to write it:
procedure foo();
var
s1: TStringList = nil;
s2: TStringList = nil;
s3: TStringList = nil;
begin
try
s1:=TStringList.create;
s2:=TStringList.create;
s3:=TStringList.create;
doWhatever(s1,s2,s3);
finally
FreeAndNil(s3);
FreeAndNil(s2);
FreeAndNil(s1);
end;
end;
Best regards,
Nikolay
I’ve basically never used try..finally in my own code but I have seen
really ugly nested like about in other projects.
Then your code will probably cause memory leaks in case of exceptions,
and even worse - leaks of other resources (file handles, sockets, etc.).
This a down stream consequence of exceptions right?
That's a downstream consequence having error handling with proper
cleanup, regardless of whether the language uses exceptions, or not.
Consider the case, without exceptions, as is typical for procedural APIs:
function foo: LongInt;
var
s1, s2, s3: TStringList;
begin
s1 := Create_StringList;
if s1=nil then
begin
Result := error;
exit;
end;
s2 := Create_StringList;
if s2=nil then
begin
Free_StringList(s1);
Result := error;
exit;
end;
s3 := Create_StringList;
if s3=nil then
begin
Free_StringList(s1);
Free_StringList(s2);
Result := error;
exit;
end;
if not doWhatever(s1, s2, s3) then
begin
Free_StringList(s1);
Free_StringList(s2);
Free_StringList(s3);
Result := error;
exit;
end;
{...etc.}
Free_StringList(s1);
Free_StringList(s2);
Free_StringList(s3);
end;
As you can see, it's more complicated and more error prone. You can
simplify it a little bit with goto, but it will never be better,
compared to try...finally
Best regards,
Nikolay
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