Re: add-relative-load-path ?

[Neil Jerram <neil@ossau.homelinux.net>]

Andy Wingo <wingo@pobox.com> writes:

> Hi Neil,
>
> Thanks for the feedback!
>
> On Sun 22 Jan 2012 00:17, Neil Jerram <neil@ossau.homelinux.net> writes:
>
>> Thing 1 is that (current-filename) can return a relative filename, or a
>> filename with a "./" in its middle
> [...]
>>
>> Would there be any downside from putting [canonicalize-path] inside
>> current-filename, so that current-filename always returns a canonical
>> file name?
>
> No, and I think that is the right thing to do in this case, because it
> avoids embedding assumptions about the current working directory into
> compiled .go files.  I have made this change.

Thanks.

>> Thing 2 is that it remains slightly inelegant to cater for both 1.8 and
>> 2.0.  I think the minimal complete solution is to write
>>
>> (cond-expand (guile-2 (include "setup-load-path.scm"))
>>              (else (load "setup-load-path.scm")))
>>
>> at top level in every uninstalled script, and then something like
>>
>> (cond-expand (guile-2
>> 	      (add-to-load-path
>> 	       (dirname
>> 		(dirname
>> 		 (canonicalize-path (current-filename))))))
>> 	     (else
>>               ;; Less elegant code for 1.8...
>> 	      (let* ((bindir (dirname (car (command-line))))
>> 		     (absdir (cond ((string=? bindir ".")
>> 				    (getcwd))
>> 				   ((string-match "^/" bindir)
>> 				    bindir)
>> 				   (else
>> 				    (in-vicinity (getcwd) bindir)))))
>> 		(set! %load-path (cons (in-vicinity absdir "..")
>> 				       %load-path)))))
>>
>> in setup-load-path.scm.
>>
>> But without a time machine I don't think anything can be done to make
>> either of those fragments more concise.
>
> Well, you could instead do:
>
>   (cond-expand ((not guile-2) (load "guile-2.0-compat.scm")))

Well it seems it has to be

  (cond-expand (guile-2)
    	       (else (load "guile-2.0-compat.scm")))

because cond-expand errors if no clause is satisfied.

>   (add-to-load-path (dirname (dirname (current-filename))))
>
> Then in guile-2.0-compat.scm you have shims to make guile 1.8 offer a
> 2.0 interface (in this case, current-filename and add-to-load-path).

But yes, indeed that is nicer, and it obviously generalises to other
compatibility issues too.  Thanks for the idea!

Regards,
        Neil