R/onAttach.R

In gdata: Various R Programming Tools for Data Manipulation

.onAttach <- function(libname, pkgname)
  {
    show <- function(...)
      packageStartupMessage(
         paste(
            strwrap(x = list(...), 
                    prefix = "gdata: "), 
            collapse="\n",sep="\n"
            )
      ) 

    try(
        {
          
          ## 1 - Can we access perl?
          hasPerl <- try( findPerl(), silent=TRUE)
          if(inherits(hasPerl, "try-error"))
            show(
        "
        Unable to locate valid perl interpreter
        \n
        \n
        read.xls() will be unable to read Excel XLS and XLSX files
        unless the 'perl=' argument is used to specify the location of
        a valid perl intrpreter.
        \n
        \n
        (To avoid display of this message in the future, please ensure perl
         is installed and available on the executable search path.)
        ")


          formats <- try(xlsFormats(),silent=TRUE)
          msg <- FALSE
          ## 2 - Are the libraries for XLS present?
          if( !("XLS" %in% formats) )
            {
              show(
                   "Unable to load perl libaries needed by read.xls()",
                   " to support 'XLX' (Excel 97-2004) files."
                   )
              msg <- TRUE
            }
          else
            {
              show(
                   "read.xls support for 'XLS'  (Excel 97-2004) files ENABLED.")
            }

          show("\n")
          
    ## 3 - Are the libbaries for XLSX present?
    if( !("XLSX" %in% formats) )
      {
        show(
            "Unable to load perl libaries needed by read.xls()",
            " to support 'XLSX' (Excel 2007+) files."
             )
        msg <- TRUE
      }
    else
      {
        show(
            "read.xls support for 'XLSX' (Excel 2007+)   files ENABLED."
             )
      }


          
    if(msg)
      {
        show("\n")
        
        show(
              " Run the function 'installXLSXsupport()'",
              " to automatically download and install the perl",
              " libaries needed to support Excel XLS and XLSX formats."
           )
    }
        
  })
        
  }