[texworks] %!TEX root =

[Joseph Wright]

Jonathan Kew wrote:
> What if you have conflicting "program = ..." specifications in the
> current file (sub-document) and the root document; which should be used
> then?
> 
> The way "program = ..." is handled in TeXworks is slightly different
> from TeXShop, if you're familiar with its behavior. In TS, any "program
> = ..." specification *overrides* the engine that's selected in the
> toolbar popup, so Cmd-T always uses what the file specifies. In TW, on
> the other hand, the "program = ..." specification initializes the popup
> to the chosen setting when the file is opened (or when the specification
> is edited), but if the user then changes it manually, the new choice
> will be respected.
> 
> This means that when you press Cmd-T (Ctrl-T), TeXworks relies on the
> toolbar popup to tell it what to do; it doesn't inspect the "program =
> ..." line at this time. And so the engine you get is the one that's
> selected in the window where you press Cmd-T.
> 
> I'm not sure if there's any approach to this that's clearly "best",
> within the model where you can have a number of files that may have
> differing metadata, and you also have a user interface where you may
> specify something different yet again. A full "TeX Project" model, where
> all the component files "belong" to a project, and metadata like this is
> carried at the project level rather than added to individual files,
> would make things clearer. This may be an option in the future, but I
> don't want to make it a requirement for using the program or for being
> able to include the engine choice in the source.

Thanks for the detailed explanation.  I see that the TeXworks model does
make this a little complicated.

One thing to bear in mind is that you get whatever the *current window*
has in the drop-down, even if the master file is already open. I'd
(naively) imagined that the flow was:
- Open or "switch" to main file (switch logically, not necessarily
graphically);
- Typeset;
- "Switch" back to current window.
As you'll see, I'd imagined that if I'd already got the main file open
the preference there would "win".

My suggestion would be that nothing changes from a code point of view
(it is perfectly logical as it is), but that the behaviour is
documented.  Essentially this means saying something like:

If you specify a main file using
% !TEX root = <file>

you should also include a

% !TEX program = <program>

line in each sub-file. This will ensure that your preference will be
followed irrespective of the active window when you typeset.
-- 
Joseph Wright