Re: What does an OClosure look like?

[Alan Mackenzie <acm@muc.de>]

Hello, Michael.

On Wed, Mar 01, 2023 at 19:46:41 +0100, Michael Heerdegen wrote:
> Alan Mackenzie <acm@muc.de> writes:

> > I'm currently experimenting with the layout of lambda forms.  In doing
> > so, I've hit a cl-assert in oclosure.el.

> Maybe show your code.

Er, the diff file is approaching 1000 lines at the moment.  ;-)

> > I can't find a description of an oclosure in that source file, nor in
> > the section in the elisp manual.  By description, I mean what an
> > oclosure structure looks like in terms of conses and lists.

> AFAIU these are ATM more or less normal function values with some meta
> data stored at some place that does not change the "behavior" (see
> `oclosure-type') when funcalling the thing.

> The cl related part implements the type handling and the
> semantics of this "meta data" (accessors).

> A byte code oclosure can't be described in terms of conses and lists of
> course.  What's your use case so that these internal implementation
> details matter?

I'm trying to change the layout of lambda forms.  This involves changing
the layout of oclosures.  In particular, I'm trying to add a field to a
lambda which identifies the enclosing defun or macro, so that this can
be output on backtraces.  Currently very little information appears on
backtraces about lambda functions.

I got where I needed to go a few days ago, but it cost several hours of
tedious source reading.  Oclosures also mess with the function Ffunction
in eval.c, which didn't make things easier.

Still I fixed the bugs I introduced.

Thanks for the reply!

> Michael.

-- 
Alan Mackenzie (Nuremberg, Germany).