[Rd] bquote/evalq behavior changed in R-3.2.1

Dayne Filer dayne.filer at gmail.com
Wed Jul 15 21:35:19 CEST 2015

In 3.1.2 eval does not store the result of the bquote-generated call in the
given environment. Interestingly, in 3.2.1 eval does store the result of
the bquote-generated call in the given environment.

In other words if I run the given example with eval rather than evalq, on
3.1.2 "x" is never stored in "fenv," but it is when I run the same code on
3.2.1. However, the given example stores "x" in "fenv" on 3.1.2, but throws
the error I gave when run on 3.2.1.

To give credit, I received the idea for using evalq from SO:


On Wed, Jul 15, 2015 at 3:29 PM, William Dunlap <wdunlap at tibco.com> wrote:

> I am curious why you used evalq instead of eval in this code.
> Bill Dunlap
> TIBCO Software
> wdunlap tibco.com
> On Wed, Jul 15, 2015 at 11:49 AM, Dayne Filer <dayne.filer at gmail.com>
> wrote:
>> Hello,
>> I upgraded from 3.1.2 to 3.2.1 and am receiving errors on code that worked
>> as I intended previously. Briefly, I am using bquote to generate
>> expressions to modify data.table objects within a  function, so I need the
>> changes to actually be stored in the given environment. Previously, I used
>> code like the following:
>> test <- list(bquote(x <- 10))
>> fenv <- environment()
>> rapply(test, evalq, envir = fenv)
>> Although the code in the example above is much simpler, it shows the
>> problem. On 3.1.2 the expression is evaluated and x is stored as 10 in the
>> given environment, fenv. In 3.2.1 the code throws an error:
>> Error in eval(substitute(expr), envir, enclos) : object 'X' not found
>> I could not find anything in the release notes that would explain this
>> change. Changing evalq to eval works in 3.2.1, but eval does not store x
>> in
>> the given environment in 3.1.2.
>> Thanks,
>> Dayne
>>         [[alternative HTML version deleted]]
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