ROBUSTNESS: Use defaults for unset datatable.* options

[HenrikBengtsson]

Issue

If some functions, own or third-party, resets all R options to what they were prior to loading data.table, then some data.table functions fail because querying those options result in NULL values. Imagine a function that reset all R options using on.exit() to protect against side effects from some rough function call setting, say, options(warn = 2).

Reproducible example

library(data.table)

## data.table options
names <- grep("^datatable", names(options()), value = TRUE)
dtopts <- options()[names]

a <- data.table()

## remove data.table options
reset <- setNames(vector("list", length = length(dtopts)), names(dtopts))
options(reset)

b <- data.table()
#> Error in setalloccol(ans) : verbose must be TRUE or FALSE

Troubleshooting

The problem is that data.table::setalloccol() assumes that these R options are always set. For example,

args(data.table::setalloccol)
#> function (DT, n = getOption("datatable.alloccol"), verbose = getOption("datatable.verbose")) 
#> NULL

Suggestion

I'd like to argue that code should not make assumptions about R options being set, even for "internal" R options. My suggestions is to add defaults to all getOption(), e.g.

args(data.table::setalloccol)
#> function (DT, n = getOption("datatable.alloccol", 1024L), verbose = getOption("datatable.verbose", FALSE)) 
#> NULL

FWIW, from:

> options(datatable.verbose = FALSE)
> b <- data.table()
Error in setalloccol(ans) : 
  Has getOption('datatable.alloccol') somehow become unset? It should be a number, by default 1024.

it's clear your aware of this potential problem. Maybe this has already been discussion previously.

Session info

> sessionInfo()
R version 4.2.0 (2022-04-22)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 20.04.4 LTS

Matrix products: default
BLAS:   /home/hb/shared/software/CBI/R-4.2.0-gcc9/lib/R/lib/libRblas.so
LAPACK: /home/hb/shared/software/CBI/R-4.2.0-gcc9/lib/R/lib/libRlapack.so

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C              
 [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8    
 [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8   
 [7] LC_PAPER=en_US.UTF-8       LC_NAME=C                 
 [9] LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] data.table_1.14.2

loaded via a namespace (and not attached):
[1] compiler_4.2.0