[R] source a specific function

[Duncan Murdoch]

On 6/18/2007 12:11 PM, (Ted Harding) wrote:
> On 18-Jun-07 14:28:35, Gabor Grothendieck wrote:
>> This loads all the functions into an anonymous environment defined
>> by local and then exports f to the global environment.
>> 
>> f <- local({
>>       source("/a.R", local = TRUE)
>>       environment(f) <- .GlobalEnv
>>       f
>> })
> 
> That looks neat! Two questions:
> 
> 1. Would something similar work for extracting selected functions
>    from a library (assuming that you know about interdependencies)?
> 
>    E.g. something like
> 
>   f <- local({
>        library(f.etc.lib)
>        environment(f) <- .GlobalEnv
>        f
>   })

The exact syntax you list there won't work, but in any case, changing 
the environment of a function in a package is a bad idea -- it may need 
to reference things from the namespace of the package.

> 
> 2. Having done what you describe to extract just f from a source
>    file, can one then "delete" the local environment used to load
>    the source? I think what I'm basically asking is whether the
>    exporting is done "by value" (local environment deletion OK)
>    or "by reference" (deletion would destroy the exported object).

Gabor answered this:  it will go away automatically.

Duncan Murdoch