EWW debug facilities?

EWW debug facilities?

[Eli Zaretskii]

How do you debug EWW, when it fails to do something?  Perhaps I'm
missing something, but there doesn't seem to be any debug or log
facilities in eww.el.  When something goes wrong, it's useful to see a
detailed log of the URLs EWW tried to fetch, including the results,
and perhaps also the related logs from the url*.el APIs it invokes.
That should allow finding the offending code, which can then be
debugged by traditional means.

Does something like that exist?  If not, would it be a good idea to
add them?

Thanks.

Re: EWW debug facilities?

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

> How do you debug EWW, when it fails to do something?

I just use the normal Emacs debugging facilities (mainly edebug).

> Perhaps I'm missing something, but there doesn't seem to be any debug
> or log facilities in eww.el.  When something goes wrong, it's useful
> to see a detailed log of the URLs EWW tried to fetch, including the
> results, and perhaps also the related logs from the url*.el APIs it
> invokes.  That should allow finding the offending code, which can then
> be debugged by traditional means.

I have a feeling that you think eww is way more complicated than it is.
:-) eww fetches a single HTML page, renders it, and then fetches any
images the HTML may have included.

The HTML can be viewed with the `v' command, and the URL it fetched you
already know.

I haven't seen the need for logging anything.  

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

Re: EWW debug facilities?

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: emacs-devel@gnu.org
> Date: Fri, 25 Dec 2015 17:42:07 +0100
> 
> > Perhaps I'm missing something, but there doesn't seem to be any debug
> > or log facilities in eww.el.  When something goes wrong, it's useful
> > to see a detailed log of the URLs EWW tried to fetch, including the
> > results, and perhaps also the related logs from the url*.el APIs it
> > invokes.  That should allow finding the offending code, which can then
> > be debugged by traditional means.
> 
> I have a feeling that you think eww is way more complicated than it is.
> :-) eww fetches a single HTML page, renders it, and then fetches any
> images the HTML may have included.

E.g., how would one go about finding out why bug#22234 happens?  What
does it try to fetch?

> The HTML can be viewed with the `v' command, and the URL it fetched you
> already know.

I know about 'v', but it doesn't help when I get a blank page ;-)

How do I know what URL it fetched when I type RET or click on a link?
The link doesn't have to be a simple URL reference, it could be very
complex, and involve multiple redirections.

Re: EWW debug facilities?

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

>> The HTML can be viewed with the `v' command, and the URL it fetched you
>> already know.
>
> I know about 'v', but it doesn't help when I get a blank page ;-)

If you hit `v' on the blank page you'll get the HTML that rendered
blankly.  :-)  (Which was the <meta> tag.)

> How do I know what URL it fetched when I type RET or click on a link?
> The link doesn't have to be a simple URL reference, it could be very
> complex, and involve multiple redirections.

True, the URL library could be handling HTTP redirects.  URL could log
those.  But I can't recall where I'd have found that useful...

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

Re: EWW debug facilities?

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: emacs-devel@gnu.org
> Date: Fri, 25 Dec 2015 18:26:58 +0100
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> The HTML can be viewed with the `v' command, and the URL it fetched you
> >> already know.
> >
> > I know about 'v', but it doesn't help when I get a blank page ;-)
> 
> If you hit `v' on the blank page you'll get the HTML that rendered
> blankly.  :-)  (Which was the <meta> tag.)

In this case, yes.  In other cases, it said "no source" instead.

Re: EWW debug facilities?

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Lars Ingebrigtsen <larsi@gnus.org>
>> Cc: emacs-devel@gnu.org
>> Date: Fri, 25 Dec 2015 18:26:58 +0100
>> 
>> Eli Zaretskii <eliz@gnu.org> writes:
>> 
>> >> The HTML can be viewed with the `v' command, and the URL it fetched you
>> >> already know.
>> >
>> > I know about 'v', but it doesn't help when I get a blank page ;-)
>> 
>> If you hit `v' on the blank page you'll get the HTML that rendered
>> blankly.  :-)  (Which was the <meta> tag.)
>
> In this case, yes.  In other cases, it said "no source" instead.

Hm.  Do you have an example?

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no