Frank Mittelbach skrev 2012-06-07 11.54:
> Am 07.06.2012 10:15, schrieb Lars Hellström:
>>>> Other approaches I would find preferable to %<@@=foo> is to use
>>>> %%% lines (as an homage to mft) or explicit commands in the .ins
>>>> file; after all, most source files don't contain code for
>>>> multiple l3-modules.
>>> To be honest I don't like that much but perhaps this is something
>>> one just needs getting used to.
>> Note that these are "/other/ possibilities I would actually find
>> preferable to assignment-guards"; you snipped my preferred realm of
>> solution without comment.
> sorry that was after midnight. You mean
>> FWIW, an alternative way of embedding extra directives into a .dtx
>> file that I have in production is to designate a specific docstrip
>> module as containing code that is directives for the stripper. If one
>> picks the very crude syntax for "directives" that each codeline in
>> the @@ module sets the current @@ replacement then the above could
>> \@@_function:nn % Will be converted to \__foo_function:nn
>> \l_@@_variable_tl % Will be converted to \l__foo_variable_tl
> Maybe I still don't quite understand directives but
> doesn't really look much different to
> except that I think it is less readable but mileage may vary
> Perhaps you can expand on that once more?
The difference is that in %<@@> the guard is just a guard, guarding some
piece of code which may perhaps be destined for some target, whereas in
%<@@=...> it is something different that just happens to be shoehorned into
the same syntactic realm. If docstrip sees %<@@=foo> it will check if
"@@=foo" is true for any output file, which it most likely not the case and
so nothing happens, but still: an incorrect interpretation is applied to the
If docstrip sees %<@@>foo it checks whether some output file has @@ true,
and since none has it continues to the next line. My idea is that l3docstrip
could treat the @@ module (\Module in the sense of doc.sty) somewhat like a
stream of commands that it will react to immediately rather than write out
to a file. %<@@>foo is, as I wrote, a rather crude syntax to employ here;
more flexible syntaxes could be
%<@@> @@ = foo, sourceencoding = latin1
where the latter (contents is keyval list) illustrates having and setting
other parameters[*] besides the @@ replacement. Of course, there's no
particular need to call the docstrip module @@ as well in these cases.
[*] I tend to be very much back and forth regarding whether it would be
useful to support encoding conversions as part of docstripping. It's
probably not so much use for pure-TeX projects, but mixed language projects
could be another matter.
In the case where I'm employing this kind of "directives module" (with
terminal "docstrip.tcl::catalogue"), I use it as an in-.dtx catalogue of
things that can be generated from the .dtx. The reasons this became more
practical than using a traditional .ins file was because (i) the version
numbers of certain generated files had to be included in the file name (/so/
not the (La)TeX way) and (ii) it in this case turned out that the natural
unit for a source file corresponded to many small generated files.