R help - Nov 2017 - Risks of using "function <- package::function" ?

Large packages sometimes mask each other's functions and that creates a
headache, especially for teaching code, since function signatures may depend on
which order packages were loaded in. One of my students proposed using the idiom

  <function> <- <package>::<function>

... in a preamble, when we use just a small subset of functions from a larger
package. I like that idea and can't see obvious disadvantages(1).

Are there subtle risks to that approach?

Thanks!
Boris


(1) I think there could be an issue when packages that are loaded later depend
on and extend a function that has has been made local. But I'm not even sure
what happens then, and it may be more of a hypothetical anyway - can't even
think of a situation with which to test it off the top of my head.

On 16/11/2017 4:53 PM, Boris Steipe wrote:
> Large packages sometimes mask each other's functions and that creates a
headache, especially for teaching code, since function signatures may depend on
which order packages were loaded in. One of my students proposed using the idiom
> 
>    <function> <- <package>::<function>
> 
> ... in a preamble, when we use just a small subset of functions from a
larger package. I like that idea and can't see obvious disadvantages(1).
> 
> Are there subtle risks to that approach?
You might do it twice.  R isn't going to complain if you have

filter <- stats::filter

# some other code here...

filter <- dplyr::filter

in your code, but the second one will overwrite the first one.

The normal way to handle this is in the NAMESPACE file, where you should 
have

importFrom(stats, filter)

If you then have

importFrom(dplyr, filter)

you should get an warning:

Warning: replacing previous import ?stats::filter? by ?dplyr::filter? 
when loading ?testpkg?.

Duncan Murdoch

Obvious?  How about "obscurity"? Just directly use pkg::fun if you
have name collision.
-- 
Sent from my phone. Please excuse my brevity.

On November 16, 2017 4:46:15 PM PST, Duncan Murdoch <murdoch.duncan at
gmail.com> wrote:
>On 16/11/2017 4:53 PM, Boris Steipe wrote:
>> Large packages sometimes mask each other's functions and that
creates
>a headache, especially for teaching code, since function signatures may
>depend on which order packages were loaded in. One of my students
>proposed using the idiom
>> 
>>    <function> <- <package>::<function>
>> 
>> ... in a preamble, when we use just a small subset of functions from
>a larger package. I like that idea and can't see obvious
>disadvantages(1).
>> 
>> Are there subtle risks to that approach?
>
>You might do it twice.  R isn't going to complain if you have
>
>filter <- stats::filter
>
># some other code here...
>
>filter <- dplyr::filter
>
>in your code, but the second one will overwrite the first one.
>
>The normal way to handle this is in the NAMESPACE file, where you
>should 
>have
>
>importFrom(stats, filter)
>
>If you then have
>
>importFrom(dplyr, filter)
>
>you should get an warning:
>
>Warning: replacing previous import ?stats::filter? by ?dplyr::filter? 
>when loading ?testpkg?.
>
>Duncan Murdoch
>
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