Re: Error handling and Exception with an iterator.

[Robert McLay <mclay@...>]

Thanks, Alexey, that helped.  Here is a complete example with a pcall to capture the case when "path" can't be opened.  The annoying thing is that I have to resort to the "wrapper_lfs_dir()" routine so that I can get the return values via the lsfT table.  So this pretty ugly code but it does work.  

Thanks to all.

Robert McLay

--------------------------------------------------------------------------

local lfs    = require("lfs")

function wrapper_lfs_dir(path, lfsT)

   local dir_next, dir = lfs.dir(path)

   lfsT.dir_next = dir_next

   lfsT.dir      = dir

end

function main()

   local path = "/path/that/cannot/be/opened"

   local lfsT = {}

   

   local status, msg = pcall (wrapper_lfs_dir, path, lfsT)

   if (not status) then

      print(msg)

      return

   end

   local dir_next, dir = lfsT.dir_next, lfsT.dir

   while (true) do

      local f = dir_next(dir, path)

      if (not f) then

         if (dir) then

            dir:close()

         end

         break

      end

      local file = path .. "/" .. f

      print(file)

   end

   

end

main()

On Sat, Sep 8, 2018 at 3:49 AM Alexey Melnichuck <alexeymelnichuck@gmail.com> wrote:

lfs.dir returns context object startign i think from 1.6 version.

So more accurate example will be

local dir_next, dir, path = lfs.dir(path) while true do path = dir_next(dir, path) if not path then if dir then dir:close() end break end ... end

чт, 6 сент. 2018 г. в 23:50, Dirk Laurie <dirk.laurie@gmail.com>:

Op Do., 6 Sep. 2018 om 22:40 het Robert McLay <mclay@tacc.utexas.edu> geskryf:
>
> I have some code which does this under unix:
>
>      local path = "/path/to/somewhere"
>      local lfs = require("luafilesystem")
>      local posix = require("posix")
>      if (posix.access(path,"x")) then
>         for f in lfs.dir(path) do
>            ...
>         end
>      end
>
> The problem is that between the posix.access() test and the lfs.dir() call the permissions on path could change.
>
> What I would like instead is some way to ignore the error that lfs.dir() is causing.  Normally one can ignore errors with pcall() but I don't see how to use pcall with an iterator like lfs.dir().

iterator = lfs.dir()
while true do
  local f = pcall(iterator)
  if not p then break end
  ...
end