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List:       r-devel
Subject:    Re: [Rd] parent.frame(n) produces different result from sys.frame(sys.parent(n))
From:       Taras Zakharko <taras.zakharko () uzh ! ch>
Date:       2022-09-28 10:50:18
Message-ID: 792EA26B-B828-49B5-B185-4A8044E59B0D () uzh ! ch
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Thanks Brodie, this certainly seems like the same issue! I'll add some comments to \
the issue tracker and hope that this can finally be fixed. 

Best, 

Taras



 

> On 28 Sep 2022, at 12:33, Brodie Gaslam <brodie.gaslam@yahoo.com> wrote:
> 
> Hi Taras,
> 
> I have not looked in detail at your examples here, but the
> use of evalq and sys.parent makes me think these issues:
> 
> https://bugs.r-project.org/show_bug.cgi?id=17849
> https://bugs.r-project.org/show_bug.cgi?id=15531
> 
> are possibly related.
> 
> Best,
> 
> B.
> 
> 
> 
> On Wednesday, September 28, 2022 at 05:29:08 AM EDT, Taras Zakharko \
> <taras.zakharko@uzh.ch> wrote:  
> 
> 
> 
> 
> Dear all, 
> 
> The documentation states that parent.frame(n) is equivalent to \
> sys.frame(sys.parent(n)) but I have discovered a case where they produce different \
> results. Before I submit a bug report I thought it would be good to run it by the R \
> community in case it's (somehow?) expected behaviour. Consider the following MRE \
> (this is R 4.2.1 running on Apple M1): 
> f1 <- function() {
> f2()
> }
> 
> f2 <- function() {
> f3()
> }
> 
> f3 <- function() {
> evalq(check_parents(), parent.frame())
> }
> 
> check_parents <- function() {
> print(vctrs::data_frame(
> call = as.list(sys.calls()),
> frame = as.list(sys.frames()),
> parent = as.list(sys.parents())
> ))
> 
> print(parent.frame(2L))
> print(sys.frame(sys.parent(2L)))
> }
> 
> f1()
> 
> This produces
> 
> call                          frame                                          parent
> 1                                  f1()                        <environment: \
> 0x10785d408>      0 2                                  f2()                        \
> <environment: 0x107898830>      1 3                                  f3()           \
> <environment: 0x107898788>      2 4 evalq(check_parents(), parent.frame())  \
> <environment: 0x1078a1f30>      3 5 evalq(check_parents(), parent.frame())  \
> <environment: 0x107898830>      4 6                        check_parents()          \
> <environment: 0x1078a1b08>      2 <environment: 0x1078a1f30>  # parent.frame(2L)
> <environment: 0x10785d408> # sys.frame(sys.parent(2L))
> 
> It seems like parent.frame(2L) resolves to frame 4 which is not part of the call \
> stack of frame 6 at all. I haven't yet looked at the C code.  
> Best, 
> 
> Taras 
> 
> ______________________________________________
> R-devel@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel

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