Re: [boost] Slots and signals: Listening to a value

From: Douglas Gregor (doug.gregor_at_[hidden])
Date: 2007-05-21 10:47:05

On May 20, 2007, at 3:06 PM, Johan Torp wrote:
> I often find myself in the situation of wanting to listen to changes
> of a value type variable. I had a templated class called
> ConcreteObservable which encapsulated a get/set-able value and
> provided ways of listening to changes in the value. I.e.
> ConcreteObservable<bool> was a bool which you could get, set and
> listen to.
>
> 1. Does the idea of a listenable value seem sound to you or do you see
> any problems?

Looks good to me. You might consider a few minor additions:

   - A copy constructor for signalling_value, that just copies the  
underlying value
   - A copy assignment operator for signalling_value, that just  
copies the underlying value
   - A conversion to const T& (same functionality as get)
   - An assignment operator that takes a const T& (same functionality  
as set)

> 2. Is there any existing boost code that already provides this  
> functionality?

Not that I know of.

> 3. Do you see any problems with my implementation?

Looks good!

> 4. Do you have a better naming suggestion?
>     Is signalling (user code would read signalling<bool>), listenable
> or signal_value perhaps better?

Did you consider "observable_value"? Or even just "observable"?

   - Doug