R help - Sep 2010 - testing for emptyenv

Dear R-users,

Is there a way to test whether a particular environment e is equal to emtyenv(),
or for that sake whether two environments e1 and e2 are equal?

I tried a couple of ways to compare environments, but neither seem to work:
> e1 <- new.env()
> e2 <- new.env()
> e1 == e2
Error in e1 == e2 :
  comparison (1) is possible only for atomic and list
types
> all.equal(e1, e2)
[1] TRUE
> all.equal(e1, emptyenv())
[1] TRUE

My ultimate goal is to make a list of all variables in the lexical scope
(enclosure?) of a function FUN. So I thought I'd start with environment(FUN)
and apply parent.env() until I reach emptyenv(). But for this to work I need to
be able to detect that I reached emptyenv().

Thank you,
Vadim

> version
               _
platform       i386-pc-mingw32
arch           i386
os             mingw32
system         i386, mingw32
status
major          2
minor          9.1
year           2009
month          06
day            26
svn rev        48839
language       R
version.string R version 2.9.1 (2009-06-26)

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On 01/09/2010 7:03 PM, Vadim Ogranovich wrote:
> Dear R-users,
> 
> Is there a way to test whether a particular environment e is equal to
emtyenv(), or for that sake whether two environments e1 and e2 are equal?
> 
> I tried a couple of ways to compare environments, but neither seem to work:
> 
>> e1 <- new.env()
>> e2 <- new.env()
>> e1 == e2
> Error in e1 == e2 :
>   comparison (1) is possible only for atomic and list types
>> all.equal(e1, e2)
> [1] TRUE
>> all.equal(e1, emptyenv())
> [1] TRUE
> 
> My ultimate goal is to make a list of all variables in the lexical scope
(enclosure?) of a function FUN. So I thought I'd start with environment(FUN)
and apply parent.env() until I reach emptyenv(). But for this to work I need to
be able to detect that I reached emptyenv().
identical(e1, e2) should give the right answer, assuming you want e1 and 
e2 to test as different.

Duncan Murdoch

Is there a complete list of these very handy and power functions in the base
R?
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