[Monotone-devel] New commands (for mtn, in lua)

[William Uther]

Hi all,

  Having recently re-surfaced from a work crunch, I was looking at  
what it would take to get monotone used in that work project.  All  
the other current project members are users of centralised version  
control.  To ease conversion I wanted to get some commands that were  
as similar as possible to centralised commands.  (Please don't tell  
me I'm going about this the wrong way, unless you have a better way  
to convince people who want close to a drop-in replacement for their  
current system.)

  Anyway, it seemed that adding new commands to monotone was a  
hassle, and just introduced more design questions.  People suggested  
I should use scripting outside of monotone, but I wanted a cross- 
platform solution.  In the end, I decided to use the lua scripting  
within monotone, and the net.venge.monotone.lua_cmds branch was born.

This branch adds three new lua functions:

  mtn_automate(...) : This allows any of the automate commands to be  
called from lua.  The result is returned as a string.

  alias_command( new_command, old_command) : Add a new command alias  
to an existing command.

  register_command(command, abstract, description, lua_function) :  
Adds a new command to the "user" group of commands.  When the command  
is called, the associated lua function is executed.  That lua will  
normally use mtn_automate() calls to do its work.

I also added automate versions of the following normal commands:  
push, pull, sync, merge, update and commit.  These are currently not  
very 'automate' friendly in that they still output everything to  
standard out.  They work for this purpose though.

I've also added contrib/extra-commands.lua which has the following:

-- include this in your monotonerc file to gain the extra commands.

alias_command("annotate", "blame")
alias_command("annotate", "praise")

function pmup(...)
    mtn_automate("get_option", "branch")	-- make sure we have a  
valid workspace
    mtn_automate("pull")
    mtn_automate("merge")
    mtn_automate("update")
end

register_command("pup", "Pull, merge and update a workspace",
      "This command approximates the update command of a centralised  
revision control system.  " ..
      "It first contacts the server to gather new revisions, then  
merges multiple local heads " ..
      "(if any), and then it updates the workspace.", "pmup")

function cpm(...)
    mtn_automate("get_option", "branch")	-- make sure we have a  
valid workspace
    mtn_automate("commit")
    mtn_automate("pull")
    heads = mtn_automate("heads")
    words = 0
    for word in string.gfind(heads, "[^%s]+") do words=words+1 end
    if words == 1 then
        mtn_automate("push")
    else
        mtn_automate("merge")
        print("Workspace contents will not be pushed to the server.")
        print("Please check that merge was successful then push  
changes.")
    end
end

register_command("cpm", "Commit, pull, merge and push a workspace",
      "This command approximates the commit command of a centralised  
revision control system.\n" ..
      "It first commits your work to the local repository, then  
contacts the server to gather\n" ..
      "new revisions.  If there is a single head at this point, then  
the local changes are pushed\n" ..
      "to the server.  If there are multiple heads then they are  
merged, and the user is asked\n" ..
      "to check things still work before pushing the changes.", "cpm")


Any thoughts or suggestions?

If I was really going to do this right, I think we should replace the  
entire command/options C++ codebase with a lua version, and allow it  
all the be scripted/modified.  But that seems like a lot of work.  Is  
this an acceptable half-way point?

Will         :-}