On 13.02.2013 10:11, Lukasz Sokol wrote:
On 13/02/2013 07:34, Michael Müller wrote:
I'm not sure if somebody else mentioned this already but I have the feeling
that Giuliano thinks that he has to decide to use try-finally OR try-except but
there are situations where you need both. One of the criteria is if the object
is local or global since for a global object it is likely that you place the
.Free (or for a global object better FreeAndNil()) into a destructor or
finalization section (which means that you have to stop the program in case of
an error and not continue showing just a dialog) so you'll need only the
try-except if you want to catch the exception. In case of a local object you'll
ALWAYS have the lines
Obj := Class.Create;
try
// do some code
finally
Obj.Free;
end;
otherwise you'll end up with memory leaks.
If you want to catch the exception in this situation you'll put try-except
extra around try-finally so you'll end up with
Obj := Class.Create;
try
try
// do some code
finally
Obj.Free;
end;
except
writeln('We have a problem);
halt the program or reraise the exception or raise a new one
end;
Regards
To developers:
How would a generalized/packed construct like
try
[code block]
finally
[code block]
except
[code block]
end;
or what about
try
[code block]
except
[code block]
finally
[code block]
end;
In any case the semantics need to be defined correctly. E.g. in the
first case what happens if an exception is raised inside the "finally"
block? In the second case what happens if an exception is raised inside
the "except" block? Do they work like nested "try try except end finally
end" or "try try finally end except end" blocks or do they have the same
rules?
Keep this FAQ entry in mind when suggesting features:
http://www.freepascal.org/faq.var#extensionselect
(Note: I personally would have nothing against such a feature, but the
details need to be defined!)
(in other words: a try-*-end construct where * can be 'finally', or 'except',
or BOTH.)
fit into Pascal philosophy?
Advantages is mainly:
- one less indent level ('oh, I need try-except around all THAT, bugger.') to
care about;
(yeah, even with all the good tools to manage the code, it stings, that the
two
have to be separately declared and one needs to remember that...)
Would it be very complicated?
I don't know how complicated it would be (we now also need to take into
account Win64 SEH and possibly in the future also Win32 and WinCE SEH),
but it should at least be doable...
Regards,
Sven
_______________________________________________
fpc-pascal maillist - fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal
