[R] Lexical scoping/calling stack issue: R fails to recognize an argument's default value
Janko Thyson
janko.thyson at gmail.com
Sat Nov 15 14:37:03 CET 2014
Ok, I have to admit: that was a really stupid mistake :-/
I unintentionally had a trailing `,` in the call to `nestr::setNested()`
inside `optionr::setAnywhereOption()`
Here's a much simpler illustration:
*Definitions* //
setGeneric(
name = "setAnywhereOption",
signature = "id",
def = function(id, ...) standardGeneric("setAnywhereOption")
)
setMethod(
f = "setAnywhereOption",
signature = signature(id = "character"),
# definition = function(id, ...) setNested(id = id)
## --> works
# definition = function(id, ...) setNested(id = id, ...)
## --> works
definition = function(id, ...) setNested(id = id,)
## --> this leads to things get messed up with argument's default
values
## --> so the trailing `,` was causing the problem!
)
setGeneric(
name = "setNested",
signature = "id",
def = function(id, ...) standardGeneric("setNested")
)
setMethod(
f = "setNested",
signature = signature(id = "character"),
definition = function(id, ...) {
if (FALSE) {
## Omitted
} else {
setShinyReactive(id = basename(id), ...)
}
})
setShinyReactive <- function(
id,
lazy = FALSE,
is_lazy = FALSE,
push = FALSE,
typed = FALSE,
strict_set = c(0, 1, 2),
...
) {
###########
## DEBUG ##
###########
message("DEBUG/setShinyReactive/threedots")
print(list(...))
message("DEBUG/setShinyReactive/push")
print(push)
message("DEBUG/setShinyReactive/lazy")
try(print(lazy))
## --> strangely, R does not seem to like the name `lazy`
message("DEBUG/setShinyReactive/is_lazy")
print(is_lazy)
## --> this works
lazy <- is_lazy
message("DEBUG/setShinyReactive/lazy")
print(lazy)
TRUE
}
*Apply //*
setAnywhereOption(id = "test")
# DEBUG/setShinyReactive/threedots
# list()
# DEBUG/setShinyReactive/push
# [1] FALSE
# DEBUG/setShinyReactive/lazy
# Error in print(lazy) : argument is missing, with no default
# DEBUG/setShinyReactive/is_lazy
# [1] FALSE
# DEBUG/setShinyReactive/lazy
# [1] FALSE
# [1] TRUE
setAnywhereOption(id = "test", push = TRUE)
setAnywhereOption(id = "test", lazy = TRUE)
*Actual cause / solution //*
Removing the trailing `,` in the method definition of `setAnywhereOption()`:
setMethod(
f = "setAnywhereOption",
signature = signature(id = "character"),
definition = function(id, ...) setNested(id = id)
## --> works
# definition = function(id, ...) setNested(id = id,)
## --> this leads to things get messed up with argument's default
values
## --> so the trailing `,` was causing the problem!
)
setAnywhereOption(id = "test")
# DEBUG/setShinyReactive/threedots
# list()
# DEBUG/setShinyReactive/push
# [1] FALSE
# DEBUG/setShinyReactive/lazy
# [1] FALSE
# DEBUG/setShinyReactive/is_lazy
# [1] FALSE
# DEBUG/setShinyReactive/lazy
# [1] FALSE
# [1] TRUE
Now it works just fine. Also stated this as an answer as potential
reference for others that might run into similar problems:
http://stackoverflow.com/questions/26940474/lexical-scoping-calling-stack-issue-r-fails-to-recognize-an-arguments-defaul
Thanks for everyone that answered/took the time to have a look at the code
- and sorry for having thrown a complicated example at you!
It was just that at first I didn't see the wood for the trees and I thought
that the problem was caused by this very calling stack structure (spread
across three different packages).
Best regards and happy coding,
Janko
On Sat, Nov 15, 2014 at 2:06 AM, Janko Thyson <janko.thyson at gmail.com>
wrote:
> Thanks. I will try to further simplify the example.
>
> On Sat, Nov 15, 2014 at 2:01 AM, Jeff Newmiller <jdnewmil at dcn.davis.ca.us>
> wrote:
>
>> While you appear to have been thorough in providing access to your code,
>> I don't think I will install a bunch of your dev code to debug it for you.
>> The Posting Guide does say your example should be minimal, and IMO this
>> doesn't fit that description. You should extract enough generic functions
>> to replicate the structure of the call tree in a single short example.
>>
>> I suppose there could be a bug in the parameter handling, but are you
>> sure every calling point is including the "..." argument that should be?
>>
>> My second blind point is that visibility of package variables does follow
>> a complicated path, but there are good descriptions available, such as [1]
>> or [2].
>>
>> If you do think you have found a bug, the R Core team will want a minimal
>> reproducible example, and you should read the Posting Guide on bug
>> reporting to make sure your issue gets addressed.
>>
>> [1] http://obeautifulcode.com/R/How-R-Searches-And-Finds-Stuff/
>> [2] http://adv-r.had.co.nz/Environments.html
>>
>> ---------------------------------------------------------------------------
>> Jeff Newmiller The ..... ..... Go
>> Live...
>> DCN:<jdnewmil at dcn.davis.ca.us> Basics: ##.#. ##.#. Live
>> Go...
>> Live: OO#.. Dead: OO#.. Playing
>> Research Engineer (Solar/Batteries O.O#. #.O#. with
>> /Software/Embedded Controllers) .OO#. .OO#.
>> rocks...1k
>>
>> ---------------------------------------------------------------------------
>> Sent from my phone. Please excuse my brevity.
>>
>> On November 14, 2014 3:51:16 PM PST, Janko Thyson <janko.thyson at gmail.com>
>> wrote:
>> >Dear list,
>> >
>> >I just encountered a behavior that I've never seen before:
>> >
>> >Is it possible, that certain argument names (lazy in my case) are
>> >special/reserved and thus would lead to unexpected behavior when a
>> >calling
>> >stack is involved that spreads across functions of three different
>> >packages: optionr::setAnywhereOptions() calls nestr::setNested() calls
>> >reactr::setShinyReactive()?
>> >
>> >Or is there something I'm generally missing with respect the
>> >combination of
>> >lexical scoping/the frame stack, S4 and default values of function
>> >arguments.
>> >
>> >Running the following code leads to a situation where the default value
>> >of
>> >`lazy` in `reactr::setShinyReactive()` is not properly recognized while
>> >others (e.g. `push`) are recognized just fine:
>> >
>> >require("devtools")
>> >devtools::install_github("Rappster/conditionr")
>> >devtools::install_github("Rappster/nestr")
>> >devtools::install_github("Rappster/optionr")
>> >require("optionr")
>> >
>> >container <- initializeOptionContainer(overwrite = TRUE)
>> >expect_true(setAnywhereOption(id = "x_1", value = TRUE, reactive =
>> >TRUE))
>> >expect_equal(getAnywhereOption(id = "x_1"), TRUE)
>> >expect_true(res <- setAnywhereOption(id = "x_2",
>> > value = reactr::reactiveExpression(
>> > !getAnywhereOption(id = "x_1")
>> > ),
>> > reactive = TRUE))
>> >
>> >The current version of `setShinyReactive()` contains a debugging
>> >section
>> >that prints these status messages (the actual code:
>> >https://github.com/Rappster/reactr/blob/bug-28/R/setShinyReactive.r#L196
>> )
>> >
>> >DEBUG/push/before[1] FALSE
>> >DEBUG/lazy/before
>> >Error in print(lazy) : argument is missing, with no default
>> >DEBUG/is_lazy/before[1] FALSE
>> >DEBUG/lazy/after[1] FALSE
>> >
>> >It also contains my current workaround: also include an argument with
>> >name `is_lazy` (whose default)
>> >value is recognized again) and then run `lazy <- is_lazy`.
>> >
>> >You can also find this information in this Stackoverflow post:
>> >
>> http://stackoverflow.com/questions/26940474/lexical-scoping-issue-r-fails-to-recognize-an-arguments-default-value
>> >
>> >Thanks a lot for everyone that can shed some light on this!
>> >
>> >
>> >Best regards,
>> >Janko
>> >
>> > [[alternative HTML version deleted]]
>> >
>> >______________________________________________
>> >R-help at r-project.org mailing list
>> >https://stat.ethz.ch/mailman/listinfo/r-help
>> >PLEASE do read the posting guide
>> >http://www.R-project.org/posting-guide.html
>> >and provide commented, minimal, self-contained, reproducible code.
>>
>>
>
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