[R] Question on closure (lexical scoping) and encapsulation

[Peter Dalgaard BSA]

murdoch at stats.uwo.ca (Duncan Murdoch) writes:

> Shouldn't the line "attributes(x) _ NULL" have applied only to x, the
> local copy of .GlobalEnv?

I don't think so. There is only one .GlobalEnv. Environments are not
copied on assignment (or everything else breaks!). 

Think of "$<-.foo" <- function(e,name,value) assign(name,value,envir=e)

Would you have expected the assignment to go in the local copy too?

It does have unforseen side effects though:

> class(.GlobalEnv)<-"foo"
> class(.GlobalEnv)
[1] "foo"
> unclass(.GlobalEnv)
<environment: R_GlobalEnv>
> class(.GlobalEnv)
NULL


-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
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