From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Ted Zlatanov Newsgroups: gmane.emacs.devel Subject: Re: more url-utils? 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List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:139487 Archived-At: On Wed, 18 May 2011 09:16:07 -0300 Stefan Monnier wrote: >>>> 3) Asynchronous usage with a callback (`url-headers-alist', >>>> `url-headers-as-string', and `url-retrieved-ok' are still available): >>>> (with-url-contents-buffer "http://host" '((url-request-method "POST")) callback-closure >>>> (message "this will run AFTER the retrieval and the callback-closure are done")) SM> In which sense is this asynchronous? >> Same as the current url.el code. SM> So you mean that, while the `body' is run after the retrieval is done, SM> the code after with-url-contents-buffer will be run earlier? Yes in the asynchronous case. This is just one case out of several the API supports and without a body this case behaves just like `url-retrieve'. If you don't think the asynchronous body is a good idea because it's hard to read, we can eliminate it by providing a separate function for the asynchronous case that only takes a callback-closure. To me it seems reasonable the way I've done it. SM> What's the difference between the code run in call-back-closure from SM> the code in `body'? The body is easier to write explicitly but the callback-closure offers more flexibility and backwards compatibility. They are more or less the same otherwise (see below for the pseudocode), it's just different types of syntactic sugar for different situations. I think the majority of uses will be in the synchronous mode, where `with-url-contents-buffer' is very convenient. >> Since I'm proposing a macro, the callback-closure is funcalled while the >> body is inlined. SM> I don't know what you mean by "funcalled vs inlined" (in my world, SM> "inlined" means it's implemented slightly differently, but the behavior SM> is identical). They are different because the resulting code is different, I don't know how to explain it any better. Maybe if I show the pseudocode? The body passed to the macro is inlined and the callback-closure is not, so the macro will look like this in the synchronous case: `(with-temp-buffer ... get url contents ... ,@(when callback-closure '(funcall callback-closure)) ,@body) I'll need to set up a lexical bind of the callback-closure to make this work, but I think it's reasonable otherwise. I can write the actual code if you agree. Or you can tell me how the API should look. The asynchronous case will be a bit more complicated, wrapping the body in a temporary closure and using that as a second callback. But as I said above we can disallow the body in the asynchronous mode if you think that's too complicated. Ted