similar to: Inspecting promises

Displaying 20 results from an estimated 10000 matches similar to: "Inspecting promises"

2024 May 11
1
R hang/bug with circular references and promises
The following code snippet causes R to hang. This example might be a bit contrived as I was experimenting and trying to understand promises, but uses only base R. It looks like it is looking for "not_a_variable" recursively but since it doesn't exist it goes on indefinitely. x0 <- new.env() x1 <- new.env(parent = x0) parent.env(x0) <- x1 delayedAssign("v",
2005 Mar 11
3
delay() has been deprecated for 2.1.0
After a bunch of discussion in the core group, we have decided to deprecate the delay() function (which was introduced as "experimental" in R 0.50). This is the function that duplicates in R code the delayed evaluation mechanism (the promise) that's used in evaluating function arguments. The problem with delay() was that it was handled inconsistently (e.g. sometimes you would see
2012 May 22
2
how to remove the 'promise' attribute of an R object (.Random.seed)?
Hi, The problem arises when I lazyLoad() the .Random.seed from a previously saved database. To simplify the process of reproducing the problem, see the example below: ## this assignment may not really make sense, but illustrates the problem delayedAssign('.Random.seed', 1L) typeof(.Random.seed) # [1] "integer" rnorm(1) # Error in rnorm(1) : # .Random.seed is not an integer
2012 May 22
2
how to remove the 'promise' attribute of an R object (.Random.seed)?
Hi, The problem arises when I lazyLoad() the .Random.seed from a previously saved database. To simplify the process of reproducing the problem, see the example below: ## this assignment may not really make sense, but illustrates the problem delayedAssign('.Random.seed', 1L) typeof(.Random.seed) # [1] "integer" rnorm(1) # Error in rnorm(1) : # .Random.seed is not an integer
2013 May 16
3
Substitute / delayedAssign (was: Substitute unaware when promise objects are evaluated)
Duncan, Thank you for the clarification on how delayedAssign works. Should R-level interfaces to promise objects ever become available, I expect they would at time come in handy. On the subject of substitute and delayedAssign, I do have a follow-up question for the list. I'm trying to convert a named list of expression objects into an environment of promise objects. After conversion, each
2003 Aug 11
1
An inconsistency with promise in attributes
When an attribute is a delayed expression sometimes it is not forced when it is extracted. > x <- list() > attr(x, "p") <- delay(1) > x list() attr(,"p") <promise: 0x11e4bb8> > val <- attr(x, "p") > val [1] 1 > attr(x, "p") <promise: 0x11e4bb8> I am not quite sure whether the above is a bug or not but I think
2012 Oct 08
4
Capturing environment associated with a promise
Hi all, It's possible to capture the expression associated with a promise (using substitute). Is there any way to capture the environment associated with a promise? Similarly, is there any way to tell if something is a promise without accidentally evaluating it? Thanks! Hadley -- RStudio / Rice University http://had.co.nz/
2006 Oct 18
1
Error condition in evaluating a promise
Is there a way to raise an error condition when a promise is evaluated such that is can be evaluated again? Right now strange things happen when the evaluation fails: > delayedAssign("x", if (failed) stop("you have to initialize me first!") else foo) > foo <- "I'm foo" > failed<-TRUE > x Error: you have to initialize me first! > x
2013 May 15
1
Substitute unaware when promise objects are evaluated
R-devel, I used the 'substitute' function to create labels for objects inside an environment, without actually evaluating the objects, as the objects might be promises. However, I was surprised to see that 'substitute' returns the expression slot of the original promise even after the promise has been forcibly evaluated. (Doesn't the promise go away after evaluation?) This
2015 Jan 26
2
Inspect a "delayed" assigned whose value throws an error?
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
2017 Sep 18
2
issue with promises for time parameter of rep()
Greetings, The following is based on a question I raised on Stackoverflow: https://stackoverflow.com/questions/46280120/calling-printls-str-in-function-affect-behavior-of-rep/46283979#46283979 Start a new R session with an empty Global Env. Then define: f <- function(n) { print(ls.str()) rep("hello", times = n) } Now run: f(x) Instead of getting the expected "object
2019 Oct 07
4
[External] Re: should base R have a piping operator ?
> On 7 Oct 2019, at 17:04, Tierney, Luke <luke-tierney at uiowa.edu> wrote: > > Think about what happens if an > argument in a pipe stage contains a pipe. (Not completely > unreasonable, e.g. for a left_join). It should work exactly as it does in a local environment. ``` `%foo%` <- function(x, y) { env <- parent.frame() # Use `:=` to avoid partial matching on
2012 Apr 29
1
A doubt about substitute() after delayedAssign()
Hello, ?delayedAssign presents substitute() as a way to look at the expression in the promise. However, msg <- "old" delayedAssign("x", msg) msg <- "new!" x #- new! substitute(x) #- x (was 'msg' ?) Here, we just got 'x'... shouldn't we got 'msg'? Same result when the promise is not evaluated yet: delayedAssign("x",
2011 May 02
2
Using substitute to access the expression related to a promise
Hi all, The help for delayedAssign suggests that you can use substitute to access the expression associated with a promise, and the help for substitute says: "If it is a promise object, i.e., a formal argument to a function or explicitly created using ?delayedAssign()?, the expression slot of the promise replaces the symbol. But this doesn't seem to work: > a <- 1 > b <- 2
2015 Jan 26
2
Inspect a "delayed" assigned whose value throws an error?
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
2024 May 11
1
[External] R hang/bug with circular references and promises
On Sat, May 11, 2024 at 9:34?AM luke-tierney--- via R-devel <r-devel at r-project.org> wrote: > > On Sat, 11 May 2024, Travers Ching wrote: > > > The following code snippet causes R to hang. This example might be a > > bit contrived as I was experimenting and trying to understand > > promises, but uses only base R. > > This has nothing to do with promises.
2024 May 11
1
[External] R hang/bug with circular references and promises
On Sat, 11 May 2024, Travers Ching wrote: > The following code snippet causes R to hang. This example might be a > bit contrived as I was experimenting and trying to understand > promises, but uses only base R. > > It looks like it is looking for "not_a_variable" recursively but since > it doesn't exist it goes on indefinitely. > > x0 <- new.env() > x1
2007 Sep 19
3
delayedAssign
The last two lines of example(delayedAssign) give this: > e <- (function(x, y = 1, z) environment())(1+2, "y", {cat(" HO! "); pi+2}) > (le <- as.list(e)) # evaluates the promises $x <promise: 0x032b31f8> $y <promise: 0x032b3230> $z <promise: 0x032b3268> which contrary to the comment appears unevaluated. Is the comment wrong or is it supposed to
2007 Sep 20
1
copying promise
1. Is there some way to copy a promise so that the copy has the same expression in its promise as the original. In the following we y is a promise that we want to copy to z. We want z to be a promise based on the expression x since y is a promise based on the expression x. Thus the answer to the code below is desired to be z=2 but its 1, 1 and y in the next three examples so they are not the
2012 Apr 25
4
delayedAssign changing values
I'm not sure if this is a known peculiarity or a bug, but I stumbled across what I think is very odd behavior from delayedAssign. In the below example x switches values the first two times it is evaluated. > delayedAssign("x", {x <- 2; x+3}) > x==x [1] FALSE > delayedAssign("x", {x <- 2; x+3}) > x [1] 5 > x [1] 2 The ?delayedAssign documentation says