Pasting the entire example into RStudio and hitting return to evaluate
does not show this. Evaluating the finall line to print counttt
separately does.
Looks like RStudio is calling `[[` on your object when examining the
environment for the Environment panel. If this concerns you then you
should contact RStudio.
Best,
luke
On Mon, 15 Jul 2019, Rui Barradas wrote:
> Hello,
>
> Clean R 3.6.1 session on Ubuntu 19.04, RStudio 1.1.453. sessionInfo() at the
> end.
>
> I can reproduce this.
>
> counttt <- 0
>
> `[[.MYCLASS` = function(x, ...) {
> counttt <<- counttt + 1
> # browser()
> x = NextMethod()
> return(x)
> }
>
> df <- as.data.frame(matrix(1:20, nrow=5))
> class(df) <- c("MYCLASS","data.frame")
> counttt
> #[1] 9
>
>
> But there's more. I tried to print the values of x in the method and got
> really strange results
>
> counttt <- 0
>
> `[[.MYCLASS` = function(x, ...) {
> counttt <<- counttt + 1
> print(x)
> # browser()
> x = NextMethod()
> return(x)
> }
>
> df <- as.data.frame(matrix(1:20, nrow=5))
> class(df) <- c("MYCLASS","data.frame")
> counttt
> #[1] 151
>
>
> If I change print to print.data.frame it goes up to
>
> counttt
> #[1] 176
>
> With print.default back to 9. What is the print method called in the second
> example?
>
>
> sessionInfo()
> R version 3.6.1 (2019-07-05)
> Platform: x86_64-pc-linux-gnu (64-bit)
> Running under: Ubuntu 19.04
>
> Matrix products: default
> BLAS: /usr/lib/x86_64-linux-gnu/blas/libblas.so.3.8.0
> LAPACK: /usr/lib/x86_64-linux-gnu/lapack/liblapack.so.3.8.0
>
> locale:
> [1] LC_CTYPE=pt_PT.UTF-8 LC_NUMERIC=C
> [3] LC_TIME=pt_PT.UTF-8 LC_COLLATE=pt_PT.UTF-8
> [5] LC_MONETARY=pt_PT.UTF-8 LC_MESSAGES=pt_PT.UTF-8
> [7] LC_PAPER=pt_PT.UTF-8 LC_NAME=C
> [9] LC_ADDRESS=C LC_TELEPHONE=C
> [11] LC_MEASUREMENT=pt_PT.UTF-8 LC_IDENTIFICATION=C
>
> attached base packages:
> [1] stats graphics grDevices utils datasets methods
> [7] base
>
> loaded via a namespace (and not attached):
> [1] sos_2.0-0 nlme_3.1-140 matrixStats_0.54.0
> [4] fs_1.2.7 xts_0.11-2 usethis_1.5.0
> [7] lubridate_1.7.4 devtools_2.0.2 RColorBrewer_1.1-2
> [10] rprojroot_1.3-2 rbenchmark_1.0.0 tools_3.6.1
> [13] backports_1.1.4 R6_2.4.0 rpart_4.1-15
> [16] Hmisc_4.2-0 lazyeval_0.2.2 colorspace_1.4-1
> [19] nnet_7.3-12 npsurv_0.4-0 withr_2.1.2
> [22] tidyselect_0.2.5 gridExtra_2.3 prettyunits_1.0.2
> [25] processx_3.3.0 curl_3.3 compiler_3.6.1
> [28] cli_1.1.0 htmlTable_1.13.1 randomNames_1.4-0.0
> [31] dvmisc_1.1.3 desc_1.2.0 tseries_0.10-46
> [34] scales_1.0.0 checkmate_1.9.1 lmtest_0.9-36
> [37] fracdiff_1.4-2 mvtnorm_1.0-10 quadprog_1.5-6
> [40] callr_3.2.0 stringr_1.4.0 digest_0.6.18
> [43] foreign_0.8-71 rio_0.5.16 base64enc_0.1-3
> [46] stocks_1.1.4 pkgconfig_2.0.2 htmltools_0.3.6
> [49] sessioninfo_1.1.1 readxl_1.3.1 htmlwidgets_1.3
> [52] rlang_0.3.4 TTR_0.23-4 rstudioapi_0.10
> [55] quantmod_0.4-14 MLmetrics_1.1.1 zoo_1.8-5
> [58] zip_2.0.1 acepack_1.4.1 dplyr_0.8.0.1
> [61] car_3.0-2 magrittr_1.5 Formula_1.2-3
> [64] Matrix_1.2-17 Rcpp_1.0.1 munsell_0.5.0
> [67] abind_1.4-5 stringi_1.4.3 forecast_8.6
> [70] yaml_2.2.0 carData_3.0-2 MASS_7.3-51.3
> [73] pkgbuild_1.0.3 plyr_1.8.4 grid_3.6.1
> [76] parallel_3.6.1 forcats_0.4.0 crayon_1.3.4
> [79] lattice_0.20-38 haven_2.1.0 splines_3.6.1
> [82] hms_0.4.2 knitr_1.22 ps_1.3.0
> [85] pillar_1.4.0 pkgload_1.0.2 urca_1.3-0
> [88] glue_1.3.1 lsei_1.2-0 babynames_1.0.0
> [91] latticeExtra_0.6-28 data.table_1.12.2 remotes_2.0.4
> [94] cellranger_1.1.0 testthat_2.1.0 gtable_0.3.0
> [97] purrr_0.3.2 assertthat_0.2.1 ggplot2_3.1.1
> [100] openxlsx_4.1.0 xfun_0.6 survey_3.35-1
> [103] survival_2.44-1.1 timeDate_3043.102 tibble_2.1.1
> [106] memoise_1.1.0 cluster_2.0.8 toOrdinal_1.1-0.0
> [109] fitdistrplus_1.0-14 brew_1.0-6
>
>
>
> Hope this helps,
>
> Rui Barradas
>
>
> Às 13:16 de 15/07/19, Duncan Murdoch escreveu:
>> On 07/07/2019 11:49 a.m., Ghiggi Gionata wrote:
>>> Hi all !
>>>
>>> I noticed a strange behaviour of the function `class<-` when a
>>> class-specific '[[.' method is defined.
>>>
>>> Here below a reproducible example :
>>>
>>>
>>> #-------------------------------------------------------------------.
>>>
>>> counttt <- 0
>>>
>>> `[[.MYCLASS` = function(x, ...) {
>>> counttt <<- counttt + 1
>>> # browser()
>>> x = NextMethod()
>>> return(x)
>>> }
>>>
>>> df <- as.data.frame(matrix(1:20, nrow=5))
>>> class(df) <- c("MYCLASS","data.frame")
>>> counttt
>>>
>>> # The same occurs when using structure(, class=) or attr(,"class")<-
>>> df <- as.data.frame(matrix(1:20, nrow=5))
>>> df <- structure(df, class=c("MYCLASS","data.frame"))
>>> attr(df, "class") <- c("MYCLASS","data.frame")
>>>
>>> #-------------------------------------------------------------------.
>>>
>>> Why in this example `class<-` is calling `[[.MYCLASS` 9 times ?
>>>
>>> Is there a way to avoid `class<-` to call `[[.MYCLASS` ?
>>>
>>>
>>> Thank you in advance for your help and suggestions.
>>
>> This is what I see:
>>
>>
>> > counttt <- 0
>> >
>> > `[[.MYCLASS` = function(x, ...) {
>> + counttt <<- counttt + 1
>> + # browser()
>> + x = NextMethod()
>> + return(x)
>> + }
>> >
>> > df <- as.data.frame(matrix(1:20, nrow=5))
>> > class(df) <- c("MYCLASS","data.frame")
>> > counttt
>> [1] 0
>>
>> So there's something else going on in your system. Maybe post
>> sessionInfo()?
>>
>> Duncan Murdoch
>>
>> ______________________________________________
>> 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
>
--
Luke Tierney
Ralph E. Wareham Professor of Mathematical Sciences
University of Iowa Phone: 319-335-3386
Department of Statistics and Fax: 319-335-3017
Actuarial Science
241 Schaeffer Hall email: luke-tier...@uiowa.edu
Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu
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