[R] Is there a way to figure out what nonlocal variables and functions have been used in a function?

[Sharpie]

blue sky wrote:
> 
> I don't what '{' and functions available in R libraries. I can
> manually exclude '{'. Is there an easy way to exclude the functions
> from R libraries?
> 

Well, you could write a function, say isPackaged( name ), that returns TRUE
or FALSE depending on whether the object matching `name` is part of a
"package:" namespace.  Of the top of my head, a quick version would use
find():

  isPackaged <- function( name ){

    # find() returns the environment that contains 
    # the object specified by `name`

    container <- find( name )

    # Return the results of a check to see if the container 
    # is a package by looking for the string 'package:' to
    # be at the start of the result returned by find()

    return(
      grepl( '^(package:)', container ) 
    )

  }     

You could then use a function like Filter() to separate the results of
findglobals() into packaged and non-packaged variables:

x=10
f=function() {print('in f')}
g=function() {f(); print(x)}

require( codetools )

globals <- findGlobals( g )

Filter( isPackaged, globals )
[1] "{"     "print"

Filter( Negate( isPackaged ), globals )
[1] "f" "x"


There are probably corner cases that won't be handled by the above code, but
it should be a start.


Good luck!

-Charlie
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