Subject: bug#14978: 24.3.50; `savehist-printable' implementation question for strings

From: Stefan Monnier <[email-masked]>
Date: Tue, 30 Jul 2013 22:31:17 -0400

> 1. Doesn't this do the same thing as that `equal-including-properties'
>    test:

>    (and (null (text-properties-at 0 value))
>         (= 0 (next-property-change 0 value)))

I think so, yes.

>    If it does do the same thing, is it more efficient or less?

Yours might be more efficient because it avoids memory allocation.
But they probably each are more efficient in some circumstances.

> 2. Is it really necessary to exclude all text properties from a printed
>    string in order for it to be Lisp-readable?  If not, can we improve
>    this code so it is not unnecessarily restrictive?

You'd have to make sure all the properties are themselves readable.

> I'm guessing that for #2 the answer is yes, it is necessary, because a
> text property can have any Lisp value,

That's right.

> including a circular list value,

Actually circular values should be handled fine; problems come when you
bump into objects like markers, buffers, windows, processes, ...

        Stefan