From: storm@cua.dk (Kim F. Storm)
Cc: Jason Rumney <jasonr@gnu.org>, rms@gnu.org, emacs-devel@gnu.org
Subject: Re: featurep
Date: 20 Mar 2002 00:48:40 +0100 [thread overview]
Message-ID: <5xwuw8xgo7.fsf@kfs2.cua.dk> (raw)
In-Reply-To: <200203192319.g2JNJMO09092@rum.cs.yale.edu>
"Stefan Monnier" <monnier+gnu/emacs@rum.cs.yale.edu> writes:
> > Ok, but if you combine :family 'local and :datagram t, and
> > make-network-process returns nil, you really don't know whether it's
> > because it doesn't support local sockets or datagrams -- so what would
> > you try next?
>
> Why does it matter ?
> What would the code look like using your :feature thing ?
Probably not a lot different, but without checking for a feature
first, the current code will throw an error for an unsupported feature
indicating (in clear text) what the problem is.
Suppose you write a package using datagrams, and don't handle the case
where it returns nil (as you suggest). In that case, a user of your
package will just see things not working (which he can report to you
as "it doesn't work"), rather than make-network-process throwing a
"datagrams not supported" error (which will probably give you a better
understanding of the problem when he reports that to you).
> Most likely your code can handle a small fixed number of different
> combination of features. It can use :feature to decide which one
> of the alternatives to choose or it can just try them in order
> until one of them succeeds.
> I.e. I don't see how the "what would you try next" question is relevant
> since the problem also shows up with :feature.
No, but I disagree with the return nil and try next approach.
>
> > In any case, I disagree, but I don't want to be religious about this,
> > so I'll change the code to use featurep.
>
> Is it even necessary ?
> I expect that "try-it-and-see" will already catch all relevant cases.
So, yes, if you as a package author is aware of the possibility that
make-network-process returns nil on some systems for some combination
of features, than everything's fine. But if some other package author
isn't aware of this, it can be a hard bargain trying to figure out
what went wrong (as the author and the user obviously are not on the
same platform).
> I'm really not convinced that we need anything more, so I wouldn't
> bother with anything more until there's some evidence that it
> is needed. Of course, maybe you have that evidence, but I haven't seen it.
IMO, being such a multi-facetted beast, make-network-process should
throw exceptions when an unsupported feature is used. If it didn't
do that, debugging code using it would be difficult. Your proposal
takes that away (to remove a useful, but unclean :feature :-).
--
Kim F. Storm <storm@cua.dk> http://www.cua.dk
_______________________________________________
Emacs-devel mailing list
Emacs-devel@gnu.org
http://mail.gnu.org/mailman/listinfo/emacs-devel
next prev parent reply other threads:[~2002-03-19 23:48 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200203190844.g2J8iOq09224@wijiji.santafe.edu>
2002-03-19 13:39 ` featurep Kim F. Storm
2002-03-19 19:24 ` featurep Jason Rumney
2002-03-19 21:20 ` featurep Stefan Monnier
2002-03-19 23:09 ` featurep Kim F. Storm
2002-03-19 23:19 ` featurep Stefan Monnier
2002-03-19 23:48 ` Kim F. Storm [this message]
2002-03-20 0:03 ` featurep Stefan Monnier
2002-03-19 22:59 ` featurep Kim F. Storm
2002-03-21 9:04 ` featurep Richard Stallman
2002-03-21 13:12 ` featurep Kim F. Storm
2002-03-23 2:35 ` featurep Richard Stallman
2002-03-21 16:44 ` featurep Stefan Monnier
2002-03-21 19:47 ` featurep Kim F. Storm
2002-03-22 0:39 ` featurep Stefan Monnier
2002-03-22 9:14 ` featurep Kim F. Storm
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: https://www.gnu.org/software/emacs/
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=5xwuw8xgo7.fsf@kfs2.cua.dk \
--to=storm@cua.dk \
--cc=emacs-devel@gnu.org \
--cc=jasonr@gnu.org \
--cc=rms@gnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://git.savannah.gnu.org/cgit/emacs.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).