Export masks for NSE-only constructs ., J, patterns and measure

NAMESPACE

@@ -27,7 +27,7 @@ export(tstrsplit)
 export(frank)
 export(frankv)
 export(address)
-export(.SD,.N,.I,.GRP,.NGRP,.BY,.EACHI)
+export(.SD,.N,.I,.GRP,.NGRP,.BY,.EACHI, ., J, patterns, measure)
 export(rleid)
 export(rleidv)
 export(rowid)

R/data.table.R

@@ -12,6 +12,10 @@ methods::setPackageName("data.table",.global)
 #   (2) export() in NAMESPACE
 #   (3) add to vignettes/datatable-importing.Rmd#globals section
 .SD = .N = .I = .GRP = .NGRP = .BY = .EACHI = NULL
+. = function(...) NULL
+J = function(...) NULL
+patterns = function(...) NULL
+measure = function(...) NULL
 # These are exported to prevent NOTEs from R CMD check, and checkUsage via compiler.
 # But also exporting them makes it clear (to users and other packages) that data.table uses these as symbols.
 # And NULL makes it clear (to the R's mask check on loading) that they're variables not functions.

inst/tests/tests.Rraw

@@ -2181,7 +2181,7 @@ if (ncol(DT)==2L) setnames(DT,c("A","B")) # else don't stop under torture with s
 test(714, DT[,z:=6:10], data.table(A=1:5,B=5,z=6:10))
 
 # Test J alias is now removed outside DT[...] from v1.8.7 (to resolve rJava::J conflict)
-test(715, J(a=1:3,b=4), error=base_messages$missing_function("J"))
+test(715, J(a=1:3,b=4), NULL)
 
 # Test get in j
 DT = data.table(a=1:3,b=4:6)

vignettes/datatable-importing.Rmd

@@ -118,7 +118,7 @@ aggr = function (x) {
 }
 ```
 
-The case for `data.table`'s special symbols (`.SD`, `.BY`, `.N`, `.I`, `.GRP`, `.NGRP`, and `.EACHI`; see `?.N`) and assignment operator (`:=`) is slightly different. You should import whichever of these values you use from `data.table`'s namespace to protect against any issues arising from the unlikely scenario that we change the exported value of these in the future, e.g. if you want to use `.N`, `.I`, and `:=`, a minimal `NAMESPACE` would have:
+The case for `data.table`'s special symbols (`.SD`, `.BY`, `.N`, `.I`, `.GRP`, `.NGRP`, `.`, `J`, `patterns`, `measure` and `.EACHI`; see `?.N`) and assignment operator (`:=`) is slightly different. You should import whichever of these values you use from `data.table`'s namespace to protect against any issues arising from the unlikely scenario that we change the exported value of these in the future, e.g. if you want to use `.N`, `.I`, and `:=`, a minimal `NAMESPACE` would have:
 
 ```r
 importFrom(data.table, .N, .I, ':=')