refactor the .onLoad and .onAttach functions

Author: stevenpawley

R/AAA.R R/zzz.RR/AAA.R renamed to R/zzz.R

@@ -1,35 +1,44 @@
 .GRASS_CACHE <- new.env(FALSE, parent = globalenv())
 
 .onLoad <- function(lib, pkg) {
-  assign(".GRASS_old.GRASS_PAGER", Sys.getenv("GRASS_PAGER"), envir = .GRASS_CACHE)
-  Sys.setenv("GRASS_PAGER" = "cat")
-  assign(".GRASS_old.GRASS_MESSAGE_FORMAT", Sys.getenv("GRASS_MESSAGE_FORMAT"),
+  # backup original environment variables
+  assign(
+    ".GRASS_old.GRASS_PAGER",
+    Sys.getenv("GRASS_PAGER"),
     envir = .GRASS_CACHE
   )
-  assign("INIT_USED", FALSE, envir = .GRASS_CACHE)
-  assign("remove_GISRC", FALSE, envir = .GRASS_CACHE)
 
-  Sys.setenv("GRASS_MESSAGE_FORMAT" = "text")
+  assign(
+    ".GRASS_old.GRASS_MESSAGE_FORMAT",
+    Sys.getenv("GRASS_MESSAGE_FORMAT"),
+    envir = .GRASS_CACHE
+  )
 
-  gisrc <- Sys.getenv("GISRC")
-  loc <- Sys.getenv("LOCATION_NAME")
+  Sys.setenv("GRASS_PAGER" = "cat")
+  Sys.setenv("GRASS_MESSAGE_FORMAT" = "text")
 
+  # set up the GRASS_CACHE environment
+  assign("INIT_USED", FALSE, envir = .GRASS_CACHE)
+  assign("remove_GISRC", FALSE, envir = .GRASS_CACHE)
   assign("cmdCACHE", list(), envir = .GRASS_CACHE)
   assign("override_encoding", "", envir = .GRASS_CACHE)
-  SYS <- ""
+
+  # add platform type to .GRASS_CACHE
   if (.Platform$OS.type == "windows") {
-    SYS <- "WinNat"
+    platform <- "WinNat"
   } else if (.Platform$OS.type == "unix") {
-    SYS <- "unix"
+    platform <- "unix"
   } else {
-    SYS <- "unknown"
+    platform <- "unknown"
   }
-  assign("SYS", SYS, envir = .GRASS_CACHE)
-  res <- ""
-  if (SYS == "WinNat") res <- ".exe"
+  assign("SYS", platform, envir = .GRASS_CACHE)
+
+  # store the platform-specific executable extension
+  res <- ifelse(platform == "WinNat", "exe", "")
   assign("addEXE", res, envir = .GRASS_CACHE)
   assign("WN_bat", "", envir = .GRASS_CACHE)
 
+  # set up other GRASS_CACHE environment variables
   assign("ignore.stderr", FALSE, envir = .GRASS_CACHE)
   assign("stop_on_no_flags_paras", TRUE, envir = .GRASS_CACHE)
   assign("echoCmd", FALSE, envir = .GRASS_CACHE)
@@ -42,31 +51,36 @@
 }
 
 .onAttach <- function(lib, pkg) {
+  # display the GRASS version and location when the package is attached
   gisrc <- Sys.getenv("GISRC")
   loc <- Sys.getenv("LOCATION_NAME")
+
   if (nchar(gisrc) == 0) {
     gv <- "(GRASS not running)"
   } else {
     gv <- .grassVersion()
     comp <- .compatibleGRASSVersion(gv)
+
     if (!is.na(comp) && !comp) {
       stop(attr(comp, "message"))
     }
+
     assign("GV", gv, envir = .GRASS_CACHE)
     if (nchar(loc) == 0) {
       loc <- read.dcf(gisrc)[1, "LOCATION_NAME"]
     }
   }
 
-  Smess <- paste("GRASS GIS interface loaded ",
+  startup_message <- paste0(
+    "GRASS GIS interface loaded ",
     "with GRASS version: ", gv, "\n",
-    ifelse(nchar(loc) == 0, "", paste("and location: ", loc, "\n", sep = "")),
-    sep = ""
+    ifelse(nchar(loc) == 0, "", paste0("and location: ", loc, "\n"))
   )
-  packageStartupMessage(Smess, appendLF = FALSE)
+  packageStartupMessage(startup_message, appendLF = FALSE)
 }
 
 .onUnload <- function(lib, pkg) {
+  # unset the GISRC environment variable and remove gisrc file
   if (get("INIT_USED", envir = .GRASS_CACHE)) {
     if (get("remove_GISRC", envir = .GRASS_CACHE)) {
       gisrc <- Sys.getenv("GISRC")
@@ -76,9 +90,16 @@
     unlink_.gislock()
     unset.GIS_LOCK()
   }
-  Sys.setenv("GRASS_PAGER" = get(".GRASS_old.GRASS_PAGER", envir = .GRASS_CACHE))
-  Sys.setenv("GRASS_MESSAGE_FORMAT" = get(".GRASS_old.GRASS_MESSAGE_FORMAT",
-    envir = .GRASS_CACHE
-  ))
+
+  # restore original environment variables
+  Sys.setenv(
+    "GRASS_PAGER" = get(".GRASS_old.GRASS_PAGER", envir = .GRASS_CACHE)
+  )
+
+  Sys.setenv(
+    "GRASS_MESSAGE_FORMAT" =
+      get(".GRASS_old.GRASS_MESSAGE_FORMAT", envir = .GRASS_CACHE)
+  )
+
   rm(.GRASS_CACHE)
 }