Skip to content

[R-pkg-devel] Puzzled about "locked environments".

4 messages · Duncan Murdoch, Martin Morgan, Rolf Turner

Original
Rolf Turner
# 
Recently I experimented with assigning a variable within the environment 
of a function in a package that I am developing.  Slightly more explicitly:

In a function "foo()" in the package, I have lines like:

    big <- 42
    assign("big",big,envir=environment(bar))

where "bar()" is another function in the package.

This causes an error to be thrown:
The reason that I am puzzled about this is that I used this syntax 
repeatedly in my CRAN package "AssetPricing".  In this latter package 
the syntax seems to work flawlessly.  No errors are thrown.  No mention 
of "locked environments".

Why would environments get "locked" in the package that I am currently 
fooling about with, but not in the AssetPricing package?  Is there 
anything that I  can do to keep environments from getting "locked"?

Can anyone suggest where I should start looking for differences in the 
nature of the two packages?

I could possibly give more detail, but I have no idea as to what might 
be relevant.

One difference is that AssetPricing involves no dynamically loaded 
Fortran code, whereas the package that I am currently fooling about with 
*does* involve such code.  (But neither "foo()" not "bar()" make direct 
calls to .Fortran().)

Grateful for any insights.

cheers,

Rolf Turner
Duncan Murdoch
#
On 08/07/2018 6:57 PM, Rolf Turner wrote:
It may be the timing.  When R is installing a package, it executes all 
of the code in the .R files (which has been consolidated into one file, 
but that doesn't matter).  This produces all of the objects and 
functions in the package.

Then it locks the environment, so that things don't change.

Then it compiles the functions.  If they were allowed to change, then 
the compilation would have to be redone.

So perhaps AssetPricing makes the change in the .R file, processed 
before locking, and your new package does it in a function, executed by 
the user after locking.

Or maybe not.

Duncan Murdoch
Martin Morgan
#
On 07/08/2018 07:23 PM, Duncan Murdoch wrote:
AssetPricing does, at least some of the time, in the body of a function 
(the indentation is confusing)

environment(vupdate) <- new.env()
environment(scrG) <- new.env()
environment(initx) <- new.env()
environment(cev) <- new.env()

#
     assign("dS",dS,envir=environment(vupdate))
     assign("dS",dS,envir=environment(scrG))
     assign("dS",dS,envir=environment(initx))
     assign("dS",dS,envir=environment(cev))

so that assignment is to the unlocked new.env(). Presumably the new code 
assigns to bar's original environment, which is the (locked, once the 
package is loaded) package name space.

Martin Morgan
This email message may contain legally privileged and/or...{{dropped:2}}
Rolf Turner
# 
Thank you hugely.  Your suggestion nailed it.  I was *sure* that I
had tried doing

    environment(bar) <- new.env()

prior to doing the assignment and that it didn't help.  I was also sure
that in AssetPricing I done assignments into environments that *weren't* 
new.  Wrong on both counts. :-(  Jeez, it's tough being mentally 
handicapped!

Thanks very much for delving into this and for looking at the code in 
AssetPricing more carefully and perspicaciously than I did.

cheers,

Rolf
On 09/07/18 11:42, Martin Morgan wrote: