[fpc-pascal] Stack alias for ARC like memory management?

Marco van de Voort marcov at stack.nl
Wed Apr 25 13:52:04 CEST 2018

In our previous episode, Ryan Joseph said:

In our previous episode, Ryan Joseph said:
> > Most seem to be covered already by having records-with-methods. The only
> > issue is that it is a different kind of  "object?.
> I like C++ because because you opt into stack or heap at any point. If you
> use a record then you?re stuck with a record.

The problem is that the C++ object model is more complex and tiered because
of it.  Also the Pascal class mode has complications of its own (like the
multi stage constructor system and its link to exceptions) that might be
additionally complicating when stressed over two very distinct use cases.

Compare it with the situation with multiple inheritance. C++ supports more
in theory, but interfaces are more convenient and cover most scenarios. Yes,
full MI coverrs more uses cases, but are the added ones really used a lot?

We must remain critical, and not declare C++ as the gospel

And then we come back to real and preferably common usecases that are an
improvement over the
current situation.

I've used quite a lot more of records-with-methods in the last two years due
to a lot of OpenGL and charting related work, so I'm not as against
extensions in this area than I used to, but I can't really imagine the
practical uses yet, and I don't instantiate that many classes locally and
kill them again.  Most messenger types are already records, and I can't
remember any moment that it was a problem that they were not in the
inheritance hierarchy. (Maybe streaming?)

Mostly stuff like TStringLists for splitting strings, but those are not
really the kind of high performance usage that benefits from being stack

Yes, I can vaguely see some minor syntactic sugar benefits of a
autoinstantiation object.  (preferably done in a delphi compatible way)
Though IMHO improving the IDE wizards to create the skeletons more
efficiently (declare-create-try -finally-release) is equally valid.

But I'm afraid this is all just language grafitti, where everybody wants to
put its stamp on the language with a lot of little used extensions.

The challenges that Pascal faces are for the most not language related.

> Look at the little code snippet I just posted using code from another post. It?s a good example of the kind of pattern I wanted to optimize. It?s save a little block of code and a call to GetMem which is good considering how little effort goes into the keyword. In functions called from tight loops it?s actually a big save.

You mean the faulty one that frees stream twice (once because it passes
stream to en which frees it), and doesn't free stream if
freeandnil(en) gives an exception because they are in the same finally block?
> > This is patently false. Both Delphi and FPC are used professionally.
> Good news. :) That?s how it feels to me though. People are honestly
> confused when you tell them you use Pascal in 2018.  I can?t point to
> where it?s a good low-language but then they remind of c++!

Well, actually if you said you used C++ for non system or high performance
applications in 2018, I think you would get the same look.
> >>  I?ve already pretty much given up writing Mac apps with Pascal because
> >> it?s so hard to keep up to date and Swift is better than Objective-C but
> >> I?d like to keep using it for games if I can.  At the end of the day I
> >> really want to be able to say at least Pascal is a good low-level language
> >> for writing fast code but in the face of C++ that?s kind of dubious claim.
> > 
> > The dubious claim is the suggestion that detail language features are the
> > main cause for language uptake. It isn?t.
> True. Pascal is basically dead on Mac because Apple has made it so hard to
> access their system frameworks.

>  I made a parser to convert objective-c to
> Objective Pascal but it?s such a hassle to keep updated and Swift is
> replacing Objective-C anyways.  Developers tools are hard to use outside
> of Xcode also.

I gave up Mac years ago, and from what I see in mails, installing still
seems to be a big problem, mostly due to the binutils. Anyway, that is for
somebody else to comment on. I simply don't know much about current Mac,
since my last one was a G5, and I decided not to continue because Apple
deprecated carbon.

That said, I'm really happy that Microsofts next gen (UWP) platforms and
store haven't really taken off yet.

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