Finding the environment of a promise

If I understand your question, you can get the environment with  
sys.frame:

f <- function(code){
   print(sys.frame())
^-- this will always return R_GlobalEnv (see ?sys.frame - which = 0 by  
default) regardless of the function and promise.

Also the question was about the environment of the promise, not the  
function. Technically a promise can be evaluated anywhere since it  
ignores the evaluation environment and will use its creation  
environment which is what Hadley was trying to get at (and as Duncan  
was saying it's not something that is or should be available at R  
level as it's an internal implementation detail).

Cheers,
Simon
   force(code)
}

f({
a <- 1
b <- 2
})

On Wed, Sep 9, 2009 at 10:30 AM, Hadley Wickham <hadley at rice.edu>  
wrote:

Hi all,

Is it possible to determine the environment in which a promise will  
be
evaluated?  e.g.

f <- function(code) { force(code) }
f({
a <- 1
b <- 2
})

Is there any way to tell from within f that a and b will be created  
in
the global environment?

Thanks,

Hadley

--
http://had.co.nz/

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Finding the environment of a promise

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