bug#45926: Tabulated-list-mode wasteful properties

[Jean Louis <bugs@gnu.support>]

* Basil L. Contovounesios <contovob@tcd.ie> [2021-03-12 13:52]:
> Boruch Baum <boruch_baum@gmx.com> writes:
> 
> > Doing it again now. Yes. It's very simple to check for yourself. Open a
> > buffer that uses the mode and evaluate from any table line ...
> >
> >   (buffer-substring (line-beginning-position) (line-end-position))
> >
> > You should be able to clearly see all the duplication. It's easiest when
> > you have pretty-print set up to display the output in a dedicated
> > buffer, but even without that you can isearch through the duplications.
> 
> Have you tried setting print-circle non-nil first?  This will help you
> see what is actually duplicated and what is shared.

I have done that exercise where my tabulated-list-entries is only
this:

⇒ ((320295 ["320295" "Boruch  Baum" "Emacs Users"]))

and

(buffer-substring (line-beginning-position) (line-end-position))

gives me this:

a ⇒ #(" 320295   Boruch  Baum                             Emacs Users" 0 1 (tabulated-list-id 320295 tabulated-list-entry #1=["320295" "Boruch  Baum" "Emacs Users"]) 1 7 (help-echo "ID: 320295" tabulated-list-column-name #3="ID" tabulated-list-id 320295 tabulated-list-entry #1#) 7 8 (tabulated-list-column-name #3# tabulated-list-id 320295 tabulated-list-entry #1#) 8 10 (display (space :align-to 10) tabulated-list-column-name #3# tabulated-list-id 320295 tabulated-list-entry #1#) 10 22 (help-echo "Name: Boruch  Baum" tabulated-list-column-name #2="Name" tabulated-list-id 320295 tabulated-list-entry #1#) 22 23 (tabulated-list-column-name #2# tabulated-list-id 320295 tabulated-list-entry #1#) 23 51 (display (space :align-to 51) tabulated-list-column-name #2# tabulated-list-id 320295 tabulat
 ed-list-entry #1#) 51 62 (help-echo "Account: Emacs Users" tabulated-list-column-name "Account" tabulated-list-id 320295 tabulated-list-entry #1#))

If non-nil, shared substructures anywhere in the structure are printed
with ‘#N=’ before the first occurrence (in the order of the print
representation) and ‘#N#’ in place of each subsequent occurrence,
where N is a positive decimal integer.

Thus I can see that those are shared structures mostly.

Jean

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