[Rd] Inspect a "delayed" assigned whose value throws an error?

[Henrik Bengtsson]

On Mon, Jan 26, 2015 at 12:24 PM, Hadley Wickham <h.wickham at gmail.com> wrote:
> If it was any other environment than the global, you could use substitute:
>
> e <- new.env()
> delayedAssign("foo", stop("Hey!"), assign.env = e)
> substitute(foo, e)
>
> delayedAssign("foo", stop("Hey!"))
> substitute(foo)

Hmm... interesting and odd.

Unfortunately, this doesn't seem to help for reaching into the
namespace of hgu133a.db and inspecting 'hgu133aPFAM', e.g.

> library("hgu133a.db")

> substitute(hgu133aPFAM, env=ns)
Error: hgu133aPFAM is defunct. Please use select() if you need access to PFAM
  or PROSITE accessions.

> evalq(substitute(hgu133aPFAM), envir=ns)
Error: hgu133aPFAM is defunct. Please use select() if you need access to PFAM
  or PROSITE accessions.

> evalq(substitute(hgu133aPFAM, env=ns), envir=ns)
Error: hgu133aPFAM is defunct. Please use select() if you need access to PFAM
  or PROSITE accessions.

Thanks,

Henrik


>
> Hadley
>
> On Mon, Jan 26, 2015 at 12:53 PM, Henrik Bengtsson <hb at biostat.ucsf.edu> wrote:
>> Hi, I got an interesting programming challenge:
>>
>> How do you inspect an object which is assigned via delayedAssign() and
>> that throws an error as soon as it is "touched" (=the value is
>> evaluated)?  Is it possible?
>>
>>
>> MINIMAL EXAMPLE:
>>
>> $ R --vanilla
>>> delayedAssign("foo", stop("Hey!"))
>>
>> (If you find this minimal example silly/obvious, please skip down to
>> the real example at the end)
>>
>>> foo
>> Error: Hey!
>>
>>> str(foo)
>> Error in str(foo) : Hey!
>> In addition: Warning message:
>> In str(foo) : restarting interrupted promise evaluation
>>
>>> mode(foo)
>> Error in mode(foo) : Hey!
>> In addition: Warning message:
>> In mode(foo) : restarting interrupted promise evaluation
>>
>>> .Internal(inspect(foo))
>> Error: Hey!
>> In addition: Warning message:
>> restarting interrupted promise evaluation
>>
>>> traceback()
>> 1: stop("Hey!")
>>
>> Is there anyway I can inspect this object using the R API without
>> evaluating the value in the delayed assignment?  Is it possible to
>> test if this is a delayed assigned or not?
>>
>>
>> BACKGROUND:
>> The background to this is where I have a function in the R.oo package
>> that scans namespaces for functions with a certain class attribute.
>> For this I use is.function() and inherits() to inspect each object.
>> An aroma.affymetrix user reported on a problem that boiled down to the
>> following:
>>
>> # source("http://bioconductor.org/biocLite.R"); biocLite("hgu133a.db")
>>> library("hgu133a.db")
>>> is.function(hgu133aPFAM)
>> Error: hgu133aPFAM is defunct. Please use select() if you need access to PFAM
>>   or PROSITE accessions.
>>> .Internal(inspect(hgu133aPFAM))
>>
>>> traceback()
>> 3: stop(paste(msg, collapse = ""), call. = FALSE, domain = NA)
>> 2: .Defunct(msg = msg)
>> 1: (function ()
>>    {
>>        if (grepl("PFAM", x)) {
>>            bimapName <- paste0(prefix, "PFAM")
>>        }
>>        else {
>>            bimapName <- paste0(prefix, "PROSITE")
>>        }
>>        x <- dc[[bimapName]]
>>        msg = wmsg(paste0(bimapName, " is defunct. ", "Please use select() if you
>>  need access to PFAM or PROSITE accessions. \n"))
>>        if (interactive()) {
>>            .Defunct(msg = msg)
>>        }
>>    })()
>>
>> My immediate solution is to perform those tests using tryCatch(), but
>> this is interesting, because this function is such that the error is
>> only thrown in interactive() sessions, i.e. the following works:
>>
>> $ Rscript -e "hgu133a.db::hgu133aPFAM"
>> [...]
>> NULL
>>
>> This is probably also why none of my aroma.affymetrix system tests
>> caught this.  Without tracing the source code behind, which seems
>> quite nested, the above is why I believe the assignment is "delayed";
>> traceback() shows a body source code, the object evaluates to
>> different things depending on interactive().
>>
>> /Henrik
>>
>> ______________________________________________
>> R-devel at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-devel
>
>
>
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