On Fri, Dec 04, 2015 at 05:56:01PM -0800, Paul E. McKenney wrote:
> On Fri, Dec 04, 2015 at 04:38:42PM -0800, Josh Triplett wrote:
[ . . . ]
> > Because you don't want to complicate the script, or because you don't
> > want to accidentally edit the wrong version? (Note that a carefully
> > written script would mean it doesn't matter which version you edit.)
>
> I prefer the simpler script.
>
> > A third alternative would be to include the answers inline right after
> > the questions, and optionally add a tiny bit of JavaScript that hides
> > them by default and lets you click to show the answer. :)
>
> That does have some advantages. I would welcome a patch that added
> the JavaScript.
And I did try a CSS approach with this CSS definition:
<style media="screen" type="text/css">
.quick-quiz-wrap {
position: relative;
}
.quick-quiz-wrap .quick-quiz-content {
display: none;
position: absolute;
bottom: -10px;
left: 10px;
right: 10px;
background-color: lightgrey;
padding: 20px;
}
.quick-quiz-wrap:hover .quick-quiz-content {
display: block;
}
</style>
I linked to this as follows:
<link rel="stylesheet" type="text/css" href="../quick-quiz.css"
media="screen">
And used it like this:
<p><b>Quick Quiz:</b>
Wait a minute!
You said that updaters can make useful forward progress concurrently
with readers, but pre-existing readers will block
<tt>synchronize_rcu()</tt>!!!
Just who are you trying to fool???
</p>
<div class="quick-quiz-wrap">
<b>Quick Quiz Answer</b>
<div class="quick-quiz-content">
<p>First, if updaters do not wish to be blocked
by readers, they can use <tt>call_rcu()</tt> or
<tt>kfree_rcu()</tt>, which will be discussed later.
Second, even when using <tt>synchronize_rcu()</tt>,
the other update-side code does run concurrently with
readers, whether pre-existing or not.
</div>
</div>
This proved fragile. It worked in trivial cases, but with non-trivial
content in a non-trivial document, it refused to show anything on mouse
hover. Even in trivial cases, it sometimes made strange choices on
where to display the text. At this point, I drop back to the old-school
scripted approach. It has the advantage of working consistently and
providing good user experience, with the HTML unconditionally present. ;-)
Thanx, Paul
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