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[whatwg] Feedback on UndoManager spec

From: Jonas Sicking <jonas@sicking.cc>
Date: Wed, 26 Oct 2011 20:30:24 -0700
Message-ID: <CA+c2ei_3Gyrwirsg8zUNR1bG1Uw3gzkuze82Sbha=sFRuZ_Q5g@mail.gmail.com>
On Wed, Oct 26, 2011 at 10:57 AM, Aryeh Gregor <ayg at aryeh.name> wrote:
>>> 15) Is the isReapply parameter to apply() needed? ?The only place I
>>> see where it's used is if the author specifies a manual transaction
>>> but leaves off a reapply() method. ?In that case, why not just call
>>> apply() with no extra parameter? ?If the author wanted to have apply()
>>> and reapply() behave differently, they could have specified a separate
>>> reapply() method.
>> There are good arguments made by Jonas on this topic.
>> Please look at whatwg archives?on this topic.
> I looked at the archives and didn't see any good arguments. ?As far as
> I can tell, if authors wanted behavior like with the isReapply
> parameter, they could easily emulate it by changing
> ?{ apply: f }
> to
> ?{ apply: function() { f(true) }, reapply: function() { f(false) } }
> so the extra isReapply parameter doesn't give any extra control to
> authors. ?It just adds a second way to do the same thing, and
> complicates the API. ?It would be simpler and easier to understand if
> authors just had to write the extra line or two of code and specify
> separate functions for apply/reapply always, instead of being able to
> specify either two functions or one that takes a boolean parameter to
> achieve the same effect.

I think that in most implementations of the apply/reapply functions,
the differences between the functions will be minimal. I.e. most of
the time you'll want to made the same modifications to the document
the second time a action is applied as you did the first time.

By splitting it out into two callbacks we encourage people to
duplicate that code.

I'd much rather see code like:

transact = { apply: function(reapply) {
  <do lots of DOM modifications>;
  if (reapply) {
    <do reapply specific mutations>;
  unapply: ...
} }

/ Jonas
Received on Wednesday, 26 October 2011 20:30:24 UTC

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