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Re: port-filename and path canonicalization
From: |
Ludovic Courtès |
Subject: |
Re: port-filename and path canonicalization |
Date: |
Tue, 20 Apr 2010 18:57:07 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) |
Hi,
Andy Wingo <address@hidden> writes:
> On Tue 20 Apr 2010 01:12, address@hidden (Ludovic Courtès) writes:
>
>> Andy Wingo <address@hidden> writes:
>>
>>> I recently added a global fluid, %file-port-name-canonicalization, which
>>> defaults to #f. But if it's 'absolute, the port name of a file port will
>>> be canonicalized to the absolute path; or, if it's 'relative, the port
>>> name is the canonical name of the file, relative to the %load-path, or
>>> the file name as given otherwise.
>>>
>>> The intention was to allow the user to control (port-filename P), so
>>> that the user could find e.g. the absolute path corresponding to that
>>> port at the time that it was made.
>>
>> My feeling is that ports shouldn’t have to deal with paths because
>> that’s a separate concern. The %file-port-name-canonicalization fluid
>> seems like an inelegant hack to me.
>>
>> When applications have special requirements about paths, then it should
>> be up to the application logic to deal with that.
IOW, applications are free to do:
(open-input-file (canonicalize-path filename))
instead of:
(open-input-file filename)
And that’s all it takes at the application level.
> 2. I think a fluid is still necessary, because a file being
> compiled can do an `include' or `include-from-path', or even
> `open-input-file' in a macro, and all these cases you would want the
> same %file-port-name-canonicalization to take effect.
Indeed, this one is tricky.
I still think it’s application-specific, though. How about calling the
fluid, say, %compiler-file-name-canonicalization instead? :-)
> 3. The only correct time to do a path canonicalization is when the file
> is opened, because at another time, you might not be in the same current
> directory, so relative paths would resolve incorrectly.
Yes.
> 4. The application-level code is nastier if it has to canonicalize,
> because a relative canonicalization
What do you mean by “relative canonicalization”?
(I have Glibc’s ‘canonicalize_file_name ()’ in mind, which returns an
absolute path, so I’m confused.)
> cannot in general be passed to open-input-file. For example
>
> (open-input-file "../../module/ice-9/boot-9.scm")
>
> is not the same as
>
> (open-input-file "ice-9/boot-9.scm")
Agreed. :-)
> So you'd have to do a set-port-filename! on the port, mucking up your
> code -- and how would you decide what to set? In N places you'd have to
> duplicate fport_canonicalize_filename, and you'd probably have to make
> scm_i_relativize_path public.
I failed to get the transition at “So”. :-)
What does scm_i_relativize_path do? (It lacks a leading comment, hint
hint. ;-))
Thanks for taking the time to explain!
Ludo’.
- Re: file names embedded in .go, (continued)
- port-filename and path canonicalization, Ludovic Courtès, 2010/04/19
- Re: port-filename and path canonicalization, Andy Wingo, 2010/04/20
- Re: port-filename and path canonicalization, Thien-Thi Nguyen, 2010/04/20
- Re: port-filename and path canonicalization, Ludovic Courtès, 2010/04/21
- Re: port-filename and path canonicalization, Thien-Thi Nguyen, 2010/04/21
- Re: port-filename and path canonicalization, Ludovic Courtès, 2010/04/21
- Re: port-filename and path canonicalization, Thien-Thi Nguyen, 2010/04/22
- Re: port-filename and path canonicalization,
Ludovic Courtès <=
- Re: port-filename and path canonicalization, Andy Wingo, 2010/04/22
- Re: port-filename and path canonicalization, Ludovic Courtès, 2010/04/22
Re: file names embedded in .go, Ludovic Courtès, 2010/04/19