Make the full message plural for better translator context

Author: MichaelChirico

R/data.table.R

@@ -892,8 +892,10 @@ replace_dot_alias = function(e) {
         }
         tt = lengths(byval)
         if (any(tt!=xnrow)) {
-          plural_part <- sprintf(ngettext(length(tt), "The item in the 'by' or 'keyby' list is length %s.", "The items in the 'by' or 'keyby' list have lengths %s."), brackify(tt))
-          stopf("%s Each must be length %d; the same length as there are rows in x (after subsetting if i is provided).", plural_part, xnrow)
+          stopf(ngettext(length(tt), 
+                         "The item in the 'by' or 'keyby' list is length %s. Each must be length %d; the same length as there are rows in x (after subsetting if i is provided).", 
+                         "The items in the 'by' or 'keyby' list have lengths %s. Each must be length %d; the same length as there are rows in x (after subsetting if i is provided)."),
+                brackify(tt), xnrow, domain=NA)
         }
         if (is.null(bynames)) bynames = rep.int("",length(byval))
         if (length(idx <- which(!nzchar(bynames))) && !bynull) {

po/R-data.table.pot

@@ -679,13 +679,6 @@ msgid ""
 "toString), whilst taking care to maintain distinctness in the process."
 msgstr ""
 
-#: data.table.R:896
-#, c-format
-msgid ""
-"%s Each must be length %d; the same length as there are rows in x (after "
-"subsetting if i is provided)."
-msgstr ""
-
 #: data.table.R:916
 msgid ""
 "by-expression '%s' is not named, and the auto-generated name '%s' clashed "
@@ -3315,8 +3308,12 @@ msgstr[0] ""
 msgstr[1] ""
 
 #: data.table.R:895
-msgid "The item in the 'by' or 'keyby' list is length %s."
-msgid_plural "The items in the 'by' or 'keyby' list have lengths %s."
+msgid "The item in the 'by' or 'keyby' list is length %s. Each must be length "
+"%d; the same length as there are rows in x (after subsetting if i is "
+"provided)."
+msgid_plural "The items in the 'by' or 'keyby' list have lengths %s. Each "
+"must be length %d; the same length as there are rows in x (after subsetting "
+"if i is provided)."
 msgstr[0] ""
 msgstr[1] ""