[MACTCL] Unix pipe to Wish in MacOS X?

[Kent B. <ke...@er...>]

The OpenSource Erlang development environment uses wish as an back-end
for graphics. The front-end written in Erlang send commands over pipes
or a socket to wish and wish send response back to Erlang as text over
the same pipes or socket. We use pipes on Unix and socket on Windows.

I try to port the Erlang graphic handling to MacOS X but have some
problems. First I can't figure out how to pipe things to the "Wish
Shell". It works on other Unix platforms but not on MacOS X. The Tcl
script that read from the pipe looks like

  fconfigure stdin -buffering line -blocking 0

  fileevent stdin readable main_reader

  proc main_reader {} {

      global command

      if {[gets stdin line] < 0} {

          if {[eof stdin]} {
              catch {close stdin}
              exit
          }

      } else {

          # We may read command with strings spanning
          # multiple lines so we put back the \n that
          # gets took away. [Is this true or even possible?]

          append command $line "\n"

          if [info complete $command] {

  #           puts stderr "MSG $command EOMSG\r"

              if [catch {uplevel #0 $command} msg] {
                  # FIXME add \r to \n
                  puts stderr $msg
              } else {
                  puts -nonewline stdout $msg
              }

              set command ""
          }
      }

  }

[comments about how to code this better is welcome, I'm not a Tcl
programmer]

A slightly different socket version of this code that talk over
localhost between Erlang and wish works but hopefully I will gain some
performance using pipes.

I use the released 8.4.0 TAR ball to build wish. Do you know any
limitations in the MacOS X version when it comes to reading and
writing to another process over pipes?

The "Wish Shell" seem to be more oriented as a true MacOS GUI
application than a traditional XWindows application. Is it more
natural to call this script using "open myscript.tcl" than trying to
find the absolute path to the executable?  If so, I can't use pipes
can I? Something like

  % cat test-commands.tcl | open cmd-reader.tcl

kent

http://www.erlang.org/download/snapshots/