Re: [Evolution] Use of Scheme in Search Folder filters

[David Sumbler <david aeolia co uk>]

On Sat, 2020-10-10 at 19:54 +0200, Milan Crha via evolution-list wrote:
> On Sat, 2020-10-10 at 09:38 +0100, David Sumbler wrote:
> > Can somebody point me to an explanation of how such Scheme
> > expressions in Evolution should be formed, or perhaps show me how
> > (and whether) this one can be made to work?
>
>       Hi,
> I do not know whether the 'S' in 'S-Expression' means 'Scheme' (I've
> been always wondering what that letter stands for, but I was also
> always lazy to figure it out), but I'd rather suggest to use the Free
> Form Expression. It's similar, but more user friendly, I hope. In any
> case, both the GUI and the Free Form Expressions are converted into
> the
> S-Expression, because it's what is used in the background. The semi-
> documentation for the Free Form Expression can be found here:
> https://bugzilla.gnome.org/show_bug.cgi?id=550796#c10
>
> The S-Expression doesn't have any documentation. I'm not aware of any
> at least. Pointing you into the code might not be the best thing, I
> believe.
>
> Maybe it would worth to update the user documentation and add there
> some Free Form Expression examples. Such always help.
>
>       Bye,
>       Milan 

Thank you for your reply.  I had already seen the bugzilla page you
mentioned.  This is rather cryptic for someone like me who doesn't have
any knowledge of the search syntax to start with.  But so far as I can
see, using "Free Form Expression" it is not possible to compare the
value in a specific header to another value, which is what I wanted to
do.

Perhaps it simply can't be done.

I also found this:
https://www.kernel.org/doc/mirror/ols2001/evolution.pdf
Section 4.4 has some examples of "Expressions", but no comprehensive
explanation of what is possible, and again no indication that the value
comparisons that I need can be done.

David