Hi all, I recently did some UI experiments, and wanted to share the results and ask for insights.
It's been long that I've suspected that there must be something fundamentally wrong about depending on emulation of a 1970's piece of hardware in order to give power to our command lines. So far I've only been trying out ideas on paper and in my head, thinking what could work the best. A few days ago I saw TermKit[0] announced, also saw the thread on this list[1]. So I've decided to turn some of my ideas into code and over the past few days came up with mret. Grab the code[2], it depends on Python and Tkinter. Basically, it's just a working prototype. It's a frankenstein made up of bits of Python, shell and Tcl. A quick and dirty hack that gave interesting results. And I believe that a rewrite in C or Tcl will be necessary - it seems that Python doesn't really give you complete control over Tk. So, what you get is something like a terminal emulator, but not exactly. There's a window with two buffers, one for input and one for output. You type in shell commands into one and see their results in the other. You could choose which shell to run - so far tested only with dash, but it might work unchanged with python, rc, whatever. Surprisingly, many standard Unix commands either Just Work, or fail gracefully (like su, complaining that it isn't attached to a terminal). I even did an "aptitude dist-upgrade": when it asked questions interactively, it worked, and it didn't mess up the output buffer trying to "draw" progress bars during download. However, this isn't really what is interesting here. (As a matter of fact, mret is incredibly crappy as a typical terminal emulator.) The nice thing is that Tk's text widget is actually a real editor widget. Features like: dynamic line wrapping upon resize, X selection, scrolling - those all work out of the box with no additional code. But the one thing I really like about Tk is that the text widget can embed arbitrary stuff in it: images, drawable canvases, buttons, progress bars, entire windows, whatever you wish. So I've been trying to come up with a sane interface exposing this capability to programs and scripts running under mret. I thought about creating an ad-hoc language of escape codes, but that would probably end up being a total mess and still wouldn't expose full capabilities of Tk. So, why not simply pipe Tcl commands right into the interpreter governing the Tk GUI? In the end, you are able to run scripts like this: #!/bin/sh [ -z "$WISHPIPE" ] && exit 1 echo "image create photo mypic -file mypic.gif" >&$WISHPIPE echo ".mret.output image create end -image mypic" >&$WISHPIPE WISHPIPE is exported by mret and holds a file descriptor, pointing to a pipe. At the other end of that pipe is the same Tcl interpreter that Python uses to draw the Tk GUI. The interface seems fairly nice to me, and properly written programs should be always able to detect if they can take advantage of mret's capabilities. There are a few simple scripts in the distribution. Try typing these commands into mret's input: ./button.sh ./image.sh sr sr.gif I imagine that if this thing would take off, there could be a standard library of scripts for displaying and manipulating thumbnails, progress bars, canvases, whatever we could come up with. Also, it seems that there's much more you could do with Tcl&Tk: I'm thinking, dynamically adding a statusbar widget to the window, hacking the input buffer to do history/command completion, things like this. But I'm a Tcl newbie so no idea. Feedback is very welcome. Thanks, Kamil [0] http://acko.net/blog/on-termkit [1] http://lists.suckless.org/dev/1105/7965.html [2] http://diogenis.ceid.upatras.gr/~cholewinski/mret-0.2.tgz
