Customized directory import

Question

I have defined a function in a package to import some data files under a directory which is produced by a scanning device (LS55):

ls55ImportSPDirectory[dir_String?DirectoryQ,  OptionsPattern[]] := doStuff[dir]

Now I want to integrate the functionality into the import framework, so that the name ls55ImportSPDirectory won't be exposed. When I do

ImportExport`RegisterImport["LS55", ls55ImportSPDirectory]

and tried e.g. to

Import["C:\\Users\\rzhang\\work\\LS55\\", {"LS55", "Data"}]

I get this error:

(*Out: Import::nodirsup: Cannot import directory C:\Users\rzhang\work\LS55\ as LS55 *)

It seems the "Directory" type has already been registered which clashes with my customized type "LS55".

Answer 1

Here is a way that works for me (V9) by altering the normal pipeline of the Import/Export Framework.

The usual disclaimer about using undocumented functionality applies.

(* Setup *)
ls55ImportSPDirectory[dir_String, OptionsPattern[]] :=
 Module[{fname = dir <> "a.png", ret},
         If[FileExistsQ@fname, ret = "File " <> fname <> " Exists", 
                               ret = "File " <> fname <> " doesn't Exist"];
         {"existence" :> ret}]

ImportExport`RegisterImport["LS55", 
                        {"existence" :> ls55ImportSPDirectory,            
                        ls55ImportSPDirectory}, {}, 
                        "FunctionChannels" -> {"Directories"}]

(* Usage *)
Import["C:\\test\\", {"LS55", "existence"}]

(* "File C:\\test\\a.png doesn't Exist" *)