refactor: lengthDS and numNaDS return class for consistency checking

Author: timcadman

R/lengthDS.R

@@ -3,20 +3,17 @@
 #' @description This function is similar to R function \code{length}.
 #' @details The function returns the length of the input vector or list.
 #' @param x a string character, the name of a vector or list
-#' @return a numeric, the number of elements of the input vector or list.
+#' @return a list with two elements: \code{length} (the number of elements of the input
+#'   vector or list) and \code{class} (the class of the input object, for client-side
+#'   consistency checking)
 #' @author Demetris Avraam, for DataSHIELD Development Team
+#' @author Tim Cadman, Genomics Coordination Centre, UMCG, Netherlands
 #' @export
 #'
 lengthDS <- function(x){
-
-  x.var <- eval(parse(text=x), envir = parent.frame())
-
-  # find the length of the input vector or list
-  out <- length(x.var)
-
-  # return output length
-  return(out)
-
+  x.val <- .loadServersideObject(x)
+  .checkClass(obj = x.val, obj_name = x, permitted_classes = c("character", "factor", "integer", "logical", "numeric", "list", "data.frame"))
+  list(length = length(x.val), class = class(x.val))
 }
 #AGGREGATE FUNCTION
 # lengthDS

R/numNaDS.R

@@ -1,15 +1,17 @@
-#' 
+#'
 #' @title Counts the number of missing values
-#' @description this function just counts the number of missing entries 
-#' in a vector. 
-#' @param xvect a vector
-#' @return an integer, the number of missing values
+#' @description this function just counts the number of missing entries
+#' in a vector.
+#' @param x a character string, the name of a server-side vector
+#' @return a list with two elements: \code{numNA} (an integer, the number of
+#'   missing values) and \code{class} (the class of the input object, for
+#'   client-side consistency checking)
 #' @author Gaye, A.
+#' @author Tim Cadman, Genomics Coordination Centre, UMCG, Netherlands
 #' @export
 #'
-numNaDS <- function(xvect){
-  
+numNaDS <- function(x){
+  xvect <- .loadServersideObject(x)
   out <- length(which(is.na(xvect)))
-  return (out)
-  
+  list(numNA = out, class = class(xvect))
 }