From: djberg96@... (Daniel Berger)
Date: 2003-03-17T09:20:24+09:00
Subject: Re: The onion truck strikes again ... Announcing rake

Jim Weirich <jweirich@one.net> wrote in message news:<1047700803.26404.123.camel@traken>...
> Ok, let me state from the beginning that I never intended to write this
> code.  I'm not convinced it is useful, and I'm not convinced anyone
> would even be interested in it.  All I can say is that Why's onion truck
> must by been passing through the Ohio valley.
> 
> What am I talking about? ... A Ruby version of Make.
> 
> See, I can sense you cringing already, and I agree.  The world certainly
> doesn't need yet another reworking of the "make" program.  I mean, we
> already have "ant".  Isn't that enough?
> 
> It started yesterday.  I was helping a coworker fix a problem in one of
> the Makefiles we use in our project.  Not a particularly tough problem,
> but during the course of the conversation I began lamenting some of the
> shortcomings of make.  In particular, in one of my makefiles I wanted to
> determine the name of a file dynamically and had to resort to some
> simple scripting (in Ruby) to make it work.  "Wouldn't it be nice if you
> could just use Ruby inside a Makefile" I said.
> 
> My coworker (a recent convert to Ruby) agreed, but wondered what it
> would look like.  So I sketched the following on the whiteboard...
> 
>     "What if you could specify the make tasks in Ruby, like this ..."
> 
>       task "build" do
>         java_compile(...args, etc ...)
>       end
> 
>     "The task function would register "build" as a target to be made,
>     and the block would be the action executed whenever the build
>     system determined that it was time to do the build target."
> 
> We agreed that would be cool, but writing make from scratch would be WAY
> too much work.  And that was the end of that!
> 
> .. Except I couldn't get the thought out of my head.  What exactly
> would be needed to make the about syntax work as a make file?  Hmmm, you
> would need to register the tasks, you need some way of specifying
> dependencies between tasks, and some way of kicking off the process. 
> Hey!  What if we did ... and fifteen minutes later I had a working
> prototype of Ruby make, complete with dependencies and actions.
> 
> I showed the code to my coworker and we had a good laugh.  It was just
> about a page worth of code that reproduced an amazing amount of the
> functionality of make.  We were both truely stunned with the power of
> Ruby.
> 
> But it didn't do everything make did.  In particular, it didn't have
> timestamp based file dependencies (where a file is rebuilt if any of its
> prerequisite files have a later timestamp).  Obviously THAT would be a
> pain to add and so Ruby Make would remain an interesting experiment.
> 
> .. Except as I walked back to my desk, I started thinking about what
> file based dependecies would really need.  Rats!  I was hooked again,
> and by adding a new class and two new methods, file/timestamp
> dependencies were implemented.
> 
> Ok, now I was really hooked.  Last night (during CSI!) I massaged the
> code and cleaned it up a bit.  The result is a bare-bones replacement
> for make in exactly 100 lines of code.
> 
> For the curious, you can see it at ...
>   o http://w3.one.net/~jweirich/tools/rake/rake.rb (the code)
>   o http://w3.one.net/~jweirich/tools/rake/Rakefile (example Rakefile)
>   o ftp://ftp.one.net/pub/users/jweirich/tools/rake/rake-0.1.0.tgz
>       (the complete package).
> 
>   (NOTE: The FTP server is flakey.  If it says it is busy, keep trying.
>          I'm looking into a different web/ftp hosting, but in the mean
>          time, good luck.)
> 
> Oh, about the name.  When I wrote the example Ruby Make task on my
> whiteboard, my coworker exclaimed "Oh! I have the perfect name: Rake ...
> Get it?  Ruby-Make. Rake!"  He said he envisioned the tasks as leaves
> and Rake would clean them up  ... or something like that.  Anyways, the
> name stuck.
> 
> Some quick examples ...
> 
> A simple task to delete backup files ...
> 
>    task :clean do
>      Dir['*~'].each {|fn| File.delete(fn) rescue nil }
>    end
> 
> Note that task names are symbols (they are slightly easier to type than
> quoted strings ... but you may use quoted string if you would rather). 
> Note also the use of "rescue nil" to trap and ignore errors in the
> File.delete command.
> 
> To run it, just type "rake clean".  Rake will automatically find a
> Rakefile in the current directory (or above!) and will invoke the
> targets named on the command line.  If there are no targets explicitly
> named, rake will invoke the task "default".
> 
> Here's another task with dependencies ...
> 
>    task :clobber => [:clean] do
>      sys %{rm -r tempdir}
>    end
> 
> Task :clobber depends upon task :clean, so :clean will be run before
> :clobber is executed.  "sys" is short for the "system" command (with an
> echo to standard out).
> 
> Files are specified by using the "file" command.  It is similar to the
> task command, except that the task name represents a file, and the task
> will be run only if the file doesn't exist, or if its modification time
> is earlier than any of its prerequisites.
> 
> Here is a file based dependency that will compile "hello.cc" to
> "hello.o".
> 
>    file "hello.cc"
>    file "hello.o" => ["hello.cc"] do |t|
>      srcfile = t.name.sub(/\.o$/, ".cc")
>      sys %{g++ #{srcfile} -c -o #{t.name}}
>    end
> 
> I normally specify file tasks with string (rather than symbols).  Some
> file names can't be represented by symbols.  Plus it makes the
> distinction between them more clear to the casual reader.  And yes,
> currently the "hello.cc" task with no prerequisites and no actions is
> required.
> 
> Currently writing a task for each and every file in the project would be
> tedious at best.  I envision a set of libraries to make this job
> easier.  For instance, perhaps something like this ...
> 
>    require 'rake/ctools'
>    Dir['*.c'].each do |fn|
>      c_source_file(fn)
>    end
> 
> where "c_source_file" will create all the tasks need to compile all the
> C source files in a directory.  Any number of useful libraries could be
> created for rake.
> 
> That's it.  There's no documentation (other than whats in this
> message).  Does this sound interesting to anyone?  If so, I'll continue
> to clean it up and write it up and publish it on RAA.  Otherwise, I'll
> leave it as an interesting excerise and a tribute to the power of Ruby.
> 
> Why /might/ rake be intersting to Ruby programmers.  I don't know,
> perhaps ...
> 
>    o No weird make syntax (only weird Ruby syntax :-)
>    o No need to edit or read XML (a la ant)
>    o Platform independent build scripts.
>    o Will run anywhere Ruby exists, so no need to have "make" installed.
>      If you stay away from the "sys" command and use things like
>      'ftools', you can have a perfectly platform independent
>       build script.  Also rake is only 100 lines of code, so it can
>       easily be packaged along with the rest of your code.
> 
> So ... Sorry for the long rambling message.  Like I said, I never
> intended to write this code at all.

Just an FYI, there's a Perl version at
http://www.perl.com/language/ppt/src/make/index.html.  Might be a good
baseline.

Regards,

Dan