proposition of the implementation

Author: m7pr

DESCRIPTION

@@ -64,6 +64,7 @@ Collate:
     'qenv-get_warnings.R'
     'qenv-join.R'
     'qenv-show.R'
+    'qenv-subset.R'
     'qenv-within.R'
     'teal.code-package.R'
     'utils-get_code_dependency.R'

NAMESPACE

@@ -13,6 +13,7 @@ export(get_warnings)
 export(join)
 export(new_qenv)
 export(qenv)
+export(subset)
 exportClasses(qenv)
 exportMethods(show)
 importFrom(lifecycle,badge)

R/qenv-subset.R

@@ -0,0 +1,52 @@
+#' Subset `qenv`
+#'
+#' @details
+#' Subset objects in `qenv` environment and limit the code to the necessary to build limited objects.
+#'
+#' @param object (`qenv`)
+#' @param names (`character`) names of objects included in `qenv` to subset
+#'
+#' @return
+#' `qenv` object
+#'
+#' @examples
+#' q <- qenv()
+#' q <- eval_code(q, "a <- 1;b<-2")
+#' q <- subset(q, "a")
+#'
+#' @name subset
+#' @rdname qenv
+#' @aliases subset,qenv-method
+#' @aliases subset,qenv.error,ANY-method
+#'
+#' @export
+setGeneric("subset", function(object, names) standardGeneric("subset"))
+
+setMethod("subset", signature = c("qenv"), function(object, names) {
+  # based on https://github.com/insightsengineering/teal/blob/a1087d2d3ff0c62393c3d5277cd5f184d543e2d9/R/teal_data_utils.R#L41-L64
+  checkmate::assert_class(names, "character")
+  names_in_env <- intersect(names, ls(get_env(object)))
+  if (!length(names_in_env)) {
+    return(qenv())
+  }
+
+  new_qenv <- qenv()
+  new_qenv@env <- list2env(mget(x = names_in_env, envir = get_env(object)))
+  new_qenv@code <- get_code(object, names = names_in_env)
+  # Question: what about @id, @warnings, @messages?
+  # Currently:
+  # > new_qenv@id
+  # integer(0)
+  # > new_qenv@warnings
+  # character(0)
+  # > new_qenv@messages
+  # character(0)
+  new_qenv
+
+})
+
+
+setMethod("subset", signature = c("qenv.error", "ANY"), function(object, names) {
+  object
+})
+