[asdf-devel] asdf output locations --- content files

[Robert Goldman]

....
> 
>> In the spirit of ASDF, we should be writing output-files methods and
>> then allowing your code to shuffle them, but that use-case seems to
>> break down a bit here.
>>
>> Consider providing an asdf system definition for a web site.  You want
>> to specify the relative location of the content files, which may be
>> generated by asdf operations (e.g., my parenscript example).  Those
>> content files must be findable by the code in your system.  So this
>> seems like a case where the "let the end user decide where to put the
>> output files" breaks down....  Hm.  Needs more thought.  These web
>> content files are a case where the code/data distinction is not so
>> clear, and ASDF has not handled data files well (indeed, by
>> unpredictably relocating code files, it has broken our ability to find
>> data files using *load-truename*).
>>
> I don't have a clear solution for that problem at this point.
> If anyone has one, I'm curious.
> 
> ASDF has no notion of "installed file".

Agreed, and this can be a real nuisance if your system carries data
along with it.

I thought I would mention this now.  If we're reforming file writing, we
might want to try to pick off this problem as well.

The web application is a plausible one as is, for example, a graphical
app that has image files contained with it.

Using *load-truename* to find such files is, as I mentioned earlier,
broken by use of A-B-L or any other code that wrangles the output files
of the compile-op.

What I typically do is something unpleasant like this (from memory;
possibly slightly inaccurate):

1.  In the asdf system definition file, do something like this:

(defparameter cl-user::*<sysname>-root-directory*
  (merge-pathnames (make-pathname :type :unspecific :name :unspecific)
                   *load-truename*))
;; use cl-user because you don't have access to the package(s) in the
;; as yet not loaded system...

2.  In the loaded files at some point

(with-open-file (str (merge-pathnames "imagefile.png"
                                      cl-user::*<sysname>-root-directory*))
  ....)

I'd love to see a clean way to avoid this....

Cheers,
r