bug with OutDec option and deferred_string altrep object
Thanks for the report. The approach you outlines below should work -- I'll look into it. Best, luke
On Mon, 8 Oct 2018, Michael Sannella wrote:
While implementing R's new 'altrep' functionality in the TERR engine, I discovered a bug in R's 'deferred_string' altrep object: it is not using the correct value of the 'OutDec' option when it expands a deferred_string.? See the following example: R 3.5.1: (same results in R 3.6.0 devel engine built 10/5) ? ? > options(scipen=0, OutDec=".") ? ? > as.character(123.456) ? ? [1] "123.456" ? ? > options(scipen=-5, OutDec=",") ? ? > as.character(123.456) ? ? [1] "1,23456e+02" ? ? > xx <- as.character(123.456) ? ? > options(scipen=0, OutDec=".") ? ? > xx ? ? [1] "1.23456e+02" ? ? > In the example above, the variable 'xx' is set to a deferred_string while OutDec is ','.? However, when the string is actually formatted (when xx is printed), it uses the current option value OutDec='.' to format the string.? I think that deferred_string should use the value OutDec=',' from when as.character was called. Note that the behavior is different with the 'scipen' option: The deferred_string object records the scipen=-5 value when as.character is called, and uses this value when xx is printed.? Looking at the deferred_string object, it appears that CDR(R_altrep_data1(<obj>)) is set to a scalar integer containing the scipen value at the time the deferred_string was created. Ideally, the deferred_string object would save both the scipen and OutDec option values.? I'd suggest saving these values as regular pairlist values, say by setting the data1 field to pairlist(<source>, scipen=-5L, OutDec=',') for the value of xx above.? To save space, you could avoid saving these values in the common case where scipen=0L, OutDec='.'.? It would also be better if the data1 field was a well-formed pairlist; the current value of the data1 field causes R_inspect to segfault. I understand that you probably wouldn't want to change the deferred_string structure.? An alternative fix would be to avoid this case by: ? 1. Never create a deferred_string if OutDec is not '.'. ? 2. When expanding an element of a deferred_string, temporarily set OutDec to '.'. ? ~~ Michael Sannella
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-tierney at uiowa.edu
Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu