quote() in new_property is raising an error rather than deferring execution

[genovese]

I have a property whose default should be a new object. My understanding was that using quote in new_property created such a promise, e.g., "A quoted call becomes a standard function promise in the default constructor, evaluated at the time the object is constructed" in the documentation.

With version 0.2.0.9000 (and also 0.1.1) and R version 4.4.1 on a Mac, I get the following instead

Dict <- class_environment
Foo <- new_class("Foo", properties=list(foo=new_property(Dict, default=quote(new_environment()))))

which produces the error

Error in new_property(Dict, default = quote(new_environment())) : 
  `default` must be an instance of <environment>, not a <language>

Have I misunderstood this use or how to carry it out?

Thanks for your help.

[ltuijnder]

Are you sure that you were using version 0.2.0 and not secretly version 0.1.1. Because the quote language feature only became available starting from v0.2.0. On version v0.1.1 it would indeed give the error message that you pasted.

Here is your code snippet working on my end also in R4.4.1 using S7 v0.2.0 (The version now on cran)

library(S7)
library(rlang)
Dict <- class_environment
Foo <- new_class("Foo", properties=list(foo=new_property(Dict, default=quote(new_environment()))))
Foo()
#> <Foo>
#>  @ foo:<environment: 0x55dd0a271ce8>
sessionInfo()
#> R version 4.4.1 (2024-06-14)
#> Platform: x86_64-pc-linux-gnu
#> Running under: Ubuntu 24.04.2 LTS
#> 
#> Matrix products: default
#> BLAS:   /usr/lib/x86_64-linux-gnu/openblas-pthread/libblas.so.3 
#> LAPACK: /usr/lib/x86_64-linux-gnu/openblas-pthread/libopenblasp-r0.3.26.so;  LAPACK version 3.12.0
#> 
#> locale:
#>  [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C              
#>  [3] LC_TIME=en_GB.UTF-8        LC_COLLATE=en_US.UTF-8    
#>  [5] LC_MONETARY=en_GB.UTF-8    LC_MESSAGES=en_US.UTF-8   
#>  [7] LC_PAPER=en_GB.UTF-8       LC_NAME=C                 
#>  [9] LC_ADDRESS=C               LC_TELEPHONE=C            
#> [11] LC_MEASUREMENT=en_GB.UTF-8 LC_IDENTIFICATION=C       
#> 
#> time zone: Europe/Brussels
#> tzcode source: system (glibc)
#> 
#> attached base packages:
#> [1] stats     graphics  grDevices utils     datasets  methods   base     
#> 
#> other attached packages:
#> [1] rlang_1.1.4 S7_0.2.0   
#> 
#> loaded via a namespace (and not attached):
#>  [1] digest_0.6.37     fastmap_1.2.0     xfun_0.52         glue_1.8.0       
#>  [5] knitr_1.48        htmltools_0.5.8.1 rmarkdown_2.28    lifecycle_1.0.4  
#>  [9] cli_3.6.3         reprex_2.1.1      withr_3.0.1       compiler_4.4.1   
#> [13] tools_4.4.1       evaluate_1.0.0    yaml_2.3.10       fs_1.6.4

^{Created on 2025-09-18 with reprex v2.1.1}