[PATCH v2] emacs: Pass a copy to notmuch-saved-search-sort-function

[Dmitry Kurochkin]

On Mon, 5 Mar 2012 22:55:54 +0200, Jani Nikula <jani at nikula.org> wrote:
> On Mar 5, 2012 5:43 PM, "Dmitry Kurochkin" <dmitry.kurochkin at gmail.com>
> wrote:
> >
> > On Mon, 05 Mar 2012 12:17:43 +0100, Daniel Schoepe <daniel at schoepe.org>
> wrote:
> > > On Mon, 05 Mar 2012 06:21:52 +0400, Dmitry Kurochkin <
> dmitry.kurochkin at gmail.com> wrote:
> > > > On Thu,  1 Mar 2012 21:24:38 +0100, Daniel Schoepe <daniel at schoepe.org>
> wrote:
> > > > > notmuch-saved-search-sort-function might destructively modify its
> > > > > input (`sort' does that, for instance), so it should not be given
> > > > > notmuch-saved-searches directly.
> > > > > ---
> > > >
> > > > -1
> > > >
> > > > I think we should require `notmuch-saved-search-sort-function' not to
> > > > have side effects.  Current documentation should be more clear about
> > > > this.  We need to fix `notmuch-sort-saved-searches' to copy the list
> > > > before calling `sort'.  But we should not do it in
> > > > `notmuch-hello-insert-saved-searches' for any sorting function (which
> > > > may not need this copying).
> > >
> > > My reasoning was that since sort is such a common function, many users
> > > will probably use sort for their own sorting functions, not realizing
> > > that it has side effects. This will lead to confusing behavior that's
> > > not so easy to track down.
> > >
> > > Copying the list of saved searches when running notmuch-hello does not
> > > seem be relevant to performance to me, since it's a) not called that
> > > often and b) the list of saved searches will rarely exceed 30 elements.
> > >
> > > Hence, this way we can avoid some headaches for users who define their
> > > own sorting functions at a negligible (performance) cost. Incidentally,
> > > this is also how notmuch-hello did it before the user-defined sections
> > > patches.
> > >
> >
> > I do not buy the argument that we should help users who implement their
> > own sorting functions but do not read documentation for functions they
> > use.  Apparently, those who implemented the `sort' function had similar
> > ideas.  And I do not think it is our job to add workarounds for it.
> >
> > An alternative (and IMO better) solution would be to allow customization
> > of compare function used for sorting instead of the sorting function
> > itself.
> 
> Providing the customization of the sort function is more powerful than the
> compare function. In the case of saved searches I can imagine people might
> want to partially use the original order while sort the rest (e.g.
> important ones first in predefined order, others sorted).

Valid point.

> In fact this also
> allows dropping out some elements. And renaming. And changing the queries...
> 
> (I had something like that in mind originally but then settled with just
> capitalizing the important ones to show them first.)
> 

All of these are invalid usages of `notmuch-saved-search-sort-function'.
The function is meant for sorting only (hence the name).  So the code
might assume that the function does only sorting.

I do not understand why we need such functionality (renaming,
capitalizing, etc.).  You can just rename the query itself if you want
to.  Should be easier IMO.  But if we need such functionality, we should
not misuse sorting function for it.  We can add `notmuch-saved-searches'
function which would return saved searches list (sorted, renamed and
mangled in any other way).  By default it would return
`notmuch-saved-searches' variable as is.

Regards,
  Dmitry

> BR,
> Jani.
> 
> >
> > Regards,
> >  Dmitry
> >
> > > Cheers,
> > > Daniel
> > _______________________________________________
> > notmuch mailing list
> > notmuch at notmuchmail.org
> > http://notmuchmail.org/mailman/listinfo/notmuch
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