[R] source a specific function

[Gabor Grothendieck]

1. You can do this:

> library(plotrix)
> environment(draw.arc) <- .GlobalEnv  # implicitly copies it
> detach()
> plot(1,1)
> draw.arc(1, 1, .1) # its there

2. Since the local environment we created in the prior post was anonymous
and since there are no other references to it either I assume it gets deleted
on the next garbage collection automatically.

On 6/18/07, Ted Harding <ted.harding at nessie.mcc.ac.uk> 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
>  })
>
>
> 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).
>
> Apologies, but for instance "?local" is a bit too deep for me!
>
> The underlying agenda behind these queries is the saving of
> memory space.
>
> With theanks,
> Ted.
>
> --------------------------------------------------------------------
> E-Mail: (Ted Harding) <ted.harding at nessie.mcc.ac.uk>
> Fax-to-email: +44 (0)870 094 0861
> Date: 18-Jun-07                                       Time: 17:11:15
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