[fpc-pascal] Freeing memory with exceptions

Sven Barth pascaldragon at googlemail.com
Thu May 25 07:55:39 CEST 2023

Hairy Pixels via fpc-pascal <fpc-pascal at lists.freepascal.org> schrieb am
Do., 25. Mai 2023, 04:26:

> > On May 24, 2023, at 10:11 PM, Sven Barth via fpc-pascal <
> fpc-pascal at lists.freepascal.org> wrote:
> >
> > You must have $H+ on and those are AnsiStrings? Why is there exception
> handling involved with AnsiString? I guess it needs this just in case an
> exception is thrown somewhere in the call stack?
> >
> > Because Ansi- and UnicodeString are managed types. *All* managed types
> managed string types, interfaces, Variants, managed records) must be
> finalized correctly even if an exception occurs.
> >
> That's a problem with exceptions then, they are baked into the language
> and impose a cost on all managed types now even if we use them or not. Even
> disabling the implicit stack frames (forgot what it's called) doesn't get
> around this right?

Disabling implicit exception frames does exactly what it says in the tin
and removes these automatically generated frames. This however opens you to
potential memory leaks if an exception occurs, so one should think twice
whether one uses this option.
Thankfully it's a local directive, so one can make this choice for every

But this is what "managed type" *means*: that the compiler and RTL will
make sure that it's correctly freed as long as nothing unexpected happens.


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