Hi, Sadrul Habib Chowdhury <[EMAIL PROTECTED]> writes:
> Hi. I started working on a lua script loader for screen last night. I am > quite happy with the progress so far. I would like to know what people > think about this kind of work. I discussed about this briefly with Micah > last night, and he also thought discussing this in the list would be > useful. > > I will try to answer a few questions that might come up in advance: > > * Where is the patchset? > - The current patchset is available at > http://www.pidgin.im/~sadrul/pp/scripting-lua/. The patches are against > the development version of screen > (http://git.savannah.gnu.org/gitweb/?p=screen.git) > > * What's the goal? > - The goal right now is to allow executing some user-defined function > on specific events, e.g. when a window is closed, opened, > title/position changed, a display is detached etc. etc. easily, i.e. > without requiring a recompilation/reinstallation. > > I started working on this mostly out of curiosity, to see where it > goes, and what cool things it might allow users to do. One use I have > in mind is to send some signal to the process in a window when it's not > visible in any of the displays, (and send another one when it becomes > visible for the first time). It doesn't make all that much sense to > implement such highly personalized features in screen itself. > > I am sure people will find a lot of other interesting things to do. > > * Why Lua? > - Because I like it! > To be perfectly honest, there was no compelling technical reason for me > to choose lua. I hadn't worked with lua bindings before, but I was told > it's much easier to work with than with some other scripting languages > (e.g. python!). I thought I would give it a try and find out. > > * Why not guile? > - Because I haven't seen it before, and I wasn't aware of it until Micah > told me about it last night on IRC! > > Note: with the patchset, it is possible to support multiple scripting > languages, either built-in at compile time (current), or dynamically > loaded on demand (not yet implemented, but possible semi-trivially. > [1] for details). So in theory, it will be possible to have none, > either or both lua and guile support. (and any other language someone > cares to write bindings for) I once hacked something together that was based on guile but I ran into problems with user input, IIRC. I will try to look at the problem again in the near future, hopefully. I really like the idea. Thanks for doing this! By the way, Python is also embeddable :) > * What about the bloat? > - I would refer to the commit message at [1] Screw the bloat, there are larger full-blown window managers around :-) > * Is there a sample script? > - Yes! http://www.pidgin.im/~sadrul/pp/scripting-lua/sc.lua > The 'fore_changed' function towards the end is the one that gets > executed when the foreground window for a display is changed. It prints > the list of windows (# and title), a message explaining the switch from > the previous window to the current one, and finally prints detailed > information about each display and its foreground window. The display > information includes the term, tty, user and the canvases. > > * What are the current triggers/hooks? > - Right now, only changing the foreground window in a display will > trigger a function named 'fore_changed' in the lua script. I don't have > a complete list of hooks in mind yet. I plan on adding new hooks as the > need arises. Suggestions are very welcome! > > I would love to know if people have any opinions, suggestions etc. about > this. The trend I would like to see is not just extending screen with a powerful language but reducing the C code where possible by this language. Sort of like it's done with emacs (only that emacs was probably written to this design from the beginning, I assume). Because the more you do in extension language, the more powerful commands you can provide to the scripting interface. And the more your configuration file becomes a program on its own, written for the screen library :) Hannes
