Closes #774. Fixed construction of a$b() & a[[.]]() in j.

Rdatatable · Oct 10, 2014 · 022272f · 022272f
1 parent d17aa96
commit 022272f
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Showing 3 changed files with 15 additions and 2 deletions.
diff --git a/R/data.table.R b/R/data.table.R
@@ -1,9 +1,15 @@
 deconstruct_and_eval = function(expr, envir = parent.frame(), enclos = parent.frame()) {
     if (!mode(expr) %in% c("call", "expression", "(")) return(expr)
 
+    # Fix for #774.
+    # the only place where a call is of length 1, that I can think of is 
+    # a function call with empty arguments: e.g., a[[1L]]() or a$b() or b()
+    # and in all these cases, we *don't* want to deconstruct and eval
+    # hence the "else if" statement is commented below. No existing tests 
+    # are broken in doing so. If there are other reports, will revisit.
     if (length(expr) == 1L) {
         if (is.expression(expr)) return (deconstruct_and_eval(expr[[1L]]))
-        else if (is.call(expr[[1L]])) return (list(deconstruct_and_eval(expr[[1L]])))
+        # else if (is.call(expr[[1L]])) return (list(deconstruct_and_eval(expr[[1L]])))
         else return(expr)
     }
 

diff --git a/README.md b/README.md
@@ -36,7 +36,9 @@
   8. If `DT` contains a column `class` (happens to be a reserved attribute name in R) then `DT[class=='a']` now works again without needing `options(datatable.auto.index=FALSE)`. Thanks to sunnyghkm for reporting, [#871](https://github.com/Rdatatable/data.table/issues/871).
 
   9. Some optimisations of `.SD` in `j` was done in 1.9.4, refer to [#735](https://github.com/Rdatatable/data.table/issues/735). Due to an oversight, j-expressions of the form c(lapply(.SD, ...), list(...)) were optimised improperly. This is now fixed. Thanks to @mmeierer for filing [#861](https://github.com/Rdatatable/data.table/issues/861).
-
+
+  9. `j`-expressions in `DT[, col := x$y()]` (or) `DT[, col := x[[1]]()]` are now (re)constructed properly. Thanks to @ihaddad-md for reporting. Closes [#774](https://github.com/Rdatatable/data.table/issues/774).
+
 #### NOTES
 
 

diff --git a/inst/tests/tests.Rraw b/inst/tests/tests.Rraw
@@ -5350,6 +5350,11 @@ test(1385.2, DT[id == id.sub], DT[1:4])
 DT = data.table(class=c('a','b'), x=c(1,2))
 test(1386, DT[class=='a'], DT[1])
 
+# Fix for #774 - parsing a$b() in 'j'
+DT = data.table(x=1:5, y=6:10)
+ll = list(foo = function() 1L)
+test(1387.1, copy(DT)[, z := ll$foo()], copy(DT)[, z:=1L])
+test(1387.2, copy(DT)[, z := ll[[1L]]()], copy(DT)[, z:=1L])
 
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