R devel - Jun 2009 - active bindings and ls.str

Hello,

Should active binding appear as such in ls.str.

 > makeActiveBinding( "xx", function(arg){ Sys.sleep(10) },
.GlobalEnv )
 > ls.str() # takes 10 seconds
xx :  NULL

What we see here is the result of the "setter" of the binding.

I'm attaching a patch that prints this instead:

 > ls.str()
xx : <active binding>

Although a better behaviour would be to show the binding function.

Romain

-- 
Romain Francois
Independent R Consultant
+33(0) 6 28 91 30 30
http://romainfrancois.blog.free.fr


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On Monday 29 June 2009, Romain Francois wrote:
> I'm attaching a patch that prints this instead:
>  > ls.str()
>
> xx : <active binding>
>
> Although a better behaviour would be to show the binding function.
I can see your point, but note that active bindings are not necessarily slow, 
and a special treatment may not be desirable in all use cases. For instance in 
RKWard, we use active bindings to detect, when objects are modified. To do so, 
we move *al* objects from .GlobalEnv to a hidden storage environment, and 
place corresponding active bindings in .GlobalEnv, instead. So, in our case, 
we'd clearly like for active bindings to behave just like regular objects,
as
much as possible.

Regards
Thomas

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