Re: [Gtk2hs-users] Attaching information to notebooks

[Joshua B. <jos...@gm...>]

Hi Axel,

Thanks so much for the reply. That is exactly what I was looking for.

I don't think the string argument is necessary, though. (Maybe it used
to be?) It looks like the current implementation generates a unique
attribute name from a global mvar (uniqueCnt), so I can use
objectCreateAttribute without any arguments.

Josh "Ua" Ball

On Sun, May 29, 2011 at 1:56 AM, Axel Simon <Axe...@in...> wrote:
> Hi Josh,
>
> indeed, there are ways to set and get arbitrary Haskell attributes on an
> Object. It's still a bit hacky. The way it works is that you do a
>
> myAttribute :: Attr Widget Foo
> myAttribute = unsafePerformIO $ objectCreateAttribute "myAttribute"
>
> somewhere in your project and then use 'set' and 'get' on this object.
> You can put in something more specific than Widget to make to compiler
> bark if you try to use the wrong object. You need the type signature
> since otherwise you could set a Foo and read back a Bar and get foobar'd
> (as in run-time crash because of using one type as another).
>
> Cheers,
> Axel
>
>
> On 29.05.11 07:24, Joshua Ball wrote:
>> Hi,
>>
>> What's the recommended strategy for attaching hidden information to a
>> child of a notebook?
>>
>> For example, if I'm creating a gedit clone, then I want to track the
>> "current file" with each child tab of the notebook. Where do I store
>> the current file info?
>>
>> Maintaining a map from ints to objects is not very workable - you have
>> to track the pageAdded, pageRemoved, and pageReordered events and
>> re-organize the map every one of those fires.
>>
>> Another option is to serialize the information into a hidden control
>> somewhere in the child of the notebook, but that seems very hackish.
>> And besides, it doesn't work well for things that don't serialize,
>> like mvars.
>>
>> Thoughts? Surely this has been solved many times over, and I'm just
>> missing the obvious solution.
>>
>> Josh "Ua" Ball
>>
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