R devel - Feb 2012 - function remains loaded in the search space after detaching the package

I ran into some very irritating behaviour I don't understand.  Let me
illustrate with the package gdata() and the function
print.object_size() :
> print(object.size(iris),units='Kb')
6.3 Kb
> getAnywhere(print.object_size)
A single object matching ?print.object_size? was found
It was found in the following places
  registered S3 method for print from namespace utils
  namespace:utils
with value
...

All is well. So now I load gdata
> require(gdata)
Loading required package: gdata
...
The following object(s) are masked from ?package:utils?:

    object.size

OK, this is what I would expect:
> print(object.size(iris),units='Kb')
[1] 6424
> getAnywhere(print.object_size)
2 differing objects matching ?print.object_size? were found
in the following places
  registered S3 method for print from namespace utils
  namespace:gdata
  namespace:utils
Use [] to view one of them

Now I detach gdata again
> detach(package:gdata)
But the function print.object_size is still the default for object_size objects!
> print(object.size(iris),units='Kb')
[1] 6424

And it can still be found as well:
> getAnywhere(print.object_size)
2 differing objects matching ?print.object_size? were found
in the following places
  registered S3 method for print from namespace utils
  namespace:gdata
  namespace:utils
Use [] to view one of them

Am I missing something?

Cheers
Joris

-- 
Joris Meys
Statistical consultant

Ghent University
Faculty of Bioscience Engineering
Department of Mathematical Modelling, Statistics and Bio-Informatics

tel : +32 9 264 59 87
Joris.Meys at Ugent.be
-------------------------------
Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php

>>>>> Joris Meys <jorismeys at gmail.com>
>>>>>     on Fri, 24 Feb 2012 11:24:35 +0100 writes:
    > I ran into some very irritating behaviour I don't
    > understand.  Let me illustrate with the package gdata()
    > and the function print.object_size() :

    >> print(object.size(iris),units='Kb')
    > 6.3 Kb
    >> getAnywhere(print.object_size)
    > A single object matching ?print.object_size? was found It
    > was found in the following places registered S3 method for
    > print from namespace utils namespace:utils with value ...

    > All is well. So now I load gdata

    >> require(gdata)
    > Loading required package: gdata ...  The following
    > object(s) are masked from ?package:utils?:

    >     object.size

    > OK, this is what I would expect:

    >> print(object.size(iris),units='Kb')
    > [1] 6424
    >> getAnywhere(print.object_size)
    > 2 differing objects matching ?print.object_size? were
    > found in the following places registered S3 method for
    > print from namespace utils namespace:gdata namespace:utils
    > Use [] to view one of them

    > Now I detach gdata again

    >> detach(package:gdata)

    > But the function print.object_size is still the default
    > for object_size objects!

    >> print(object.size(iris),units='Kb')
    > [1] 6424

    > And it can still be found as well:

    >> getAnywhere(print.object_size)
    > 2 differing objects matching ?print.object_size? were
    > found in the following places registered S3 method for
    > print from namespace utils namespace:gdata namespace:utils
    > Use [] to view one of them

    > Am I missing something?

Yes:  the argument  'unload'   of detach().

In general: Now that every package has a namespace,
you (and others) should learn the difference between 
attaching and loading - and hence  detach()ing and unloading
a package with its namespace.

 ?detach
 ?library

etc should give a good start.

Martin Maechler, ETH Zurich