[webkit-dev] High Resolution Timer API proposal(s)

Maciej Stachowiak mjs at apple.com
Thu Oct 2 20:19:33 PDT 2008

On Oct 2, 2008, at 6:50 PM, Aaron Boodman wrote:

> On Thu, Oct 2, 2008 at 5:05 PM, Maciej Stachowiak <mjs at apple.com>  
> wrote:
>> Timer startTimer(double delayInSeconds, bool repeating, Function
>> callback);
>> interface Timer {
>>    void stop();
>> }
> One other random idea. What about mixing up the param order for
> parallelism with the existing timer APIs:
> Timer startTimer(Function callback, double delay, bool repeating);
> That would make a call look like this:
> var timer = startTimer(function() { ... }, 42, true);
> Which feels more familiar, but at the same timer better. Less new
> things to remember. Also, I think this argues for the unit to continue
> being milliseconds, again, for familiarity.

The reason I like the other parameters first is that the function  
parameter could plausibly be quite long. Let's say you are writing a  
big continuation function inline, to communicate work in progress via  
lexically visible variables, and let's say maybe even you nest it:

startTimer(function() {
     while (true) {
         //do very important work
         // do even more important work

     if (important)

     startTimer(function() {
         // do even more important work

         if (doSomethingLater)
             startTimer(function() {

                  // stuff to do later

             }, 42, false);

        // even stillmore important stuff

     }, 0, false);

}, 0, false);

That seems pretty oogey to me.

On the other hand, I agree (as stated elsewhere in the thread) that  
constantly mentioning false for non-repeating is lame. I think there  
are three ways to deal with that:

1) Reorder the parameters as you have proposed and make the boolean  
optional (perhaps even make the time optional too, defaulting to 0).

2) Keep the parameters in the order I proposed, but make the first  
ones optional - that's a little weird, but not untenable.

3) Split the method into startTimer and startRepeatingTimer.

I think I will mention some of these possible variations when  
proposing the spec. At Hixie's suggestion I will propose it as a  
standalone spec on <public-webapps at w3.org>, I recommend that those who  
wish to follow the discussion subscribe to that list.


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