on 02/13/2009 06:05 PM Carl Witthoft wrote:
> Recently I got introduced to two packages: {seewave} and {audio} .
> Turns out they both have a tool to call a system audio tool, and in both
> cases the name of the tool is play(). Naturally these two tools do
> slightly different things with different arguments.
>
> So, what should a user do, and more to the point, what should R do? If
> I've learned the right things about environments, I could include some
> require() statements inside scripts to guarantee the right things are
> loaded (and only loaded for that script).
> But in general when there are two commands with the same name, it means
> that if I distribute code which uses the command, a random user
> elsewhere might have the other package loaded and bad things would happen.
>
>
> In a perfect world, there would be some R control database that people
> would check packages into. The database (or some poor volunteer) would
> verify there were no naming conflicts with other posted packages, and so
> on. Failing that, what are good rules for fail-safing code, or
> figuring out how to check that some package I've loaded didn't blow away
> some other tools I previously loaded?
In addition to Bert's excellent recommendation (as well as ?conflicts),
this is one of the key reasons for using namespaces.
It would appear, from a review of the tarballs for both packages, that
audio is using a namespace, but seewave does not. You might make a
recommendation to the latter's author to implement a namespace for his
package. That would help avoid the collisions in third party code.
audio does export the play() function, so you can use:
audio::play(...)
to differentiate that function from:
seewave::play(...)
None of this is a guarantee of course, if other play() functions should
be loaded or come into being, which is why namespaces are a safer approach.
See also:
http://cran.r-project.org/doc/manuals/R-intro.html#Namespaces
HTH,
Marc Schwartz
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