[Ur] More questions: sql_injectable, reactivity and interaction with CSS

Tue Jan 12 08:22:33 EST 2010

Artyom Shalkhakov wrote:
> Here's what I do:
>    
>> fun editable () =
>>    m<- source False; (* mode: editing or viewing *)
>>    t<- source "click to edit";
>>    let
>>      fun act () =
>>        m'<- signal m;
>>        return (if m' then
>>           <xml><ctextbox source={t}/><button onclick={set m False}/></xml>
>>        else<xml><dyn signal={t'<- signal t; return (cdata t')}/></xml>
>>    in
>>      return<xml><body>
>>        <div onclick={m'<- get m; if not m' then set m True else return ()}>
>>          <dyn signal={act ()}/>
>>        </div>
>>      </body></xml>
>>    end
>>      
> I think it should work but actually clicking on the button doesn't
> revert the mode from editing to viewing. Is there something I do
> wrong?
>    

Yes, and in fact it's just a simple misunderstanding, based on semantics 
inherited from HTML/JavaScript.  The <button> you create is inside the 
<div> with an 'onclick' attribute.  Thus, when you click on the button, 
_both_ 'onclick' handlers run.  The <div>'s handler cancels the effect 
of the <button>'s handler!  (You can add some [alert] calls to forcibly 
pause the process at different points; this lets you see the text appear 
and then disappear again.)