return can be used to set the return value of an expression evaluated by "eval"
expr <- quote(if (x) return(1) else return(2)) x <- FALSE eval(expr) #2 Tomas On 08/23/2017 09:46 AM, Lionel Henry wrote:
oops, I should have tried it: expr <- quote(break) repeat(eval(expr)) So eval() has hybrid semantics where `break` has more reach than return(), weird. expr <- quote(return()) repeat(eval(expr)) # infloop LionelOn 23 août 2017, at 09:24, Tomas Kalibera <tomas.kalib...@gmail.com> wrote: It is a bug in the byte-code compiler. I will fix Tomas On 08/23/2017 09:22 AM, Lionel Henry wrote:I don't think that's a bug. source() uses eval(), and eval() creates a new function-like context frame. In a way expecting `break` to work inside source() is like expecting `break` to cross stack frames: my_break <- function() break repeat(my_break()) LionelOn 23 août 2017, at 09:17, Martin Maechler <maech...@stat.math.ethz.ch> wrote:Martin Maechler <maech...@stat.math.ethz.ch> on Wed, 23 Aug 2017 09:10:20 +0200 writes: Peter Bosa <peter.b...@oregonmetro.gov> on Tue, 22 Aug 2017 14:39:50 +0000 writes:Hello, I've noticed the following error using repeat{} / break in R 3.4.1 running on Windows 10 and Windows Server 2008 (both 64-bit environments). When running a repeat function, the break command causes an error message if the repeat command refers to code within a file, but does not produce an error if the code is contained within the repeat{} command. Hello, I've noticed the following error using repeat{} / break in R 3.4.1 running on Windows 10 and Windows Server 2008 (both 64-bit environments). When running a repeat function, the break command causes an error message if the repeat command refers to code within a file, but does not produce an error if the code is contained within the repeat{} command. For example, the following code runs fine: x <- 1 y <- 5 repeat { if(x < y) { print("No Break Dance :-(") x = x + 1 } else { print("Break Dance!") break } } [1] "No Break Dance :(" [1] "No Break Dance :(" [1] "No Break Dance :(" [1] "No Break Dance :(" [1] "No Break Dance :(" [1] "Break Dance!" However, if I take the loop contents of the repeat{} function, and save them to a file (breakTest.R) that contains the following: if(x < y) { print("No Break Dance :-(") x = x + 1 } else { print("Break Dance!") break } And then run the following code: x <- 1 y <- 5 repeat{ source("./breakTest.R") } I get the following error: [1] "No Break Dance :(" [1] "No Break Dance :(" [1] "No Break Dance :(" [1] "No Break Dance :(" [1] "No Break Dance :(" [1] "Break Dance!" Error in eval(ei, envir) : no loop for break/next, jumping to top level This was not an issue with previous versions of R that I have used, including 3.3.3. Any suggestions? Is this a known bug with 3.4.1?Thank you, Peter! I can confirm what you are seeing (on Linux) in R version 3.4.0, 3.4.1, and "R devel", and also that this had worked w/o a problem in earlier versions of R, where I've looked at R version 3.3.3 and 3.2.5. I do think this is a bug, but it was not known till now. For ease of use, I attach the two R files to easily reproduce. Note I use writeLines() instead of print() as its output is "nicer". Best regards, Martin Maechler, ETH ZurichTrying again with the two attachment. Yes, I of all people (!!) should know that they must have an allowed MIME type; in this case text/plain ! Martin ## see ./break-source_R341.R if(x < y) { writeLines("No Break Dance :-(") x <- x + 1 } else { writeLines("Break Dance!") break } ## From: Peter Bosa <peter.b...@oregonmetro.gov> ## To: "R-devel@r-project.org" <R-devel@r-project.org> ## Subject: [Rd] Possible repeat{} / break function bug in R 3.4.1 ## Date: Tue, 22 Aug 2017 14:39:50 +0000 ## Hello, I've noticed the following error using repeat{} / break in R 3.4.1 running on Windows 10 and Windows Server 2008 (both 64-bit environments). ## When running a repeat function, the break command causes an error message if the repeat command refers to code within a file, but does not produce an error if the code is contained within the repeat{} command. ## For example, the following code runs fine: x <- 1 y <- 5 repeat { if(x < y) { writeLines("No Break Dance :-(") x <- x + 1 } else { writeLines("Break Dance!") break } } ## No Break Dance :( ## No Break Dance :( ## No Break Dance :( ## No Break Dance :( ## No Break Dance :( ## Break Dance! ## > ## However, if I take the loop contents of the repeat{} function, and save ## them to a file (breakTest.R) that contains the following: ## ^^^^^^^^^^^ ## __SEE THAT FILE__ ## if(x < y) { ## writeLines("No Break Dance :-(") ## x = x + 1 ## } else { ## writeLines("Break Dance!") ## break ## } ## And then run the following code: x <- 1 y <- 5 repeat{ source("./breakTest.R") } cat("successfully finished\n") ## I get the following error: ## No Break Dance :( ## No Break Dance :( ## No Break Dance :( ## No Break Dance :( ## No Break Dance :( ## Break Dance! ## Error in eval(ei, envir) : no loop for break/next, jumping to top level ## ^^^^^^^^^^^^^^^^^^^^ ## This was not an issue with previous versions of R that I have used, including 3.3.3. ## MM: It does work in R 3.3.3, indeed ## -- it fails in R 3.4.0 and later ## Any suggestions? Is this a known bug with 3.4.1? ## Cheers- ## Peter ## ---------------------------------------------------------------- ## peter bosa ## metro ## modeling services ## 600 ne grand ave ## portland, or 97232 ## peter.b...@oregonmetro.gov<mailto:peter.b...@oregonmetro.gov> ## 503.797.1771 ## metro | making a great place ## www.oregonmetro.gov ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
