[Rake-devel] Hello and a little patch for task initialisation

[Jim Weirich]

Link, Claudius wrote:
> Hello,
> 
> as it is my first post to the list
> some information on me (to keep it short only about rake and ruby :-)

Thanks for your feedback.  It is always interesting to hear how people 
are using rake in the real world.

I have a couple of questions ...

First regarding your name patch.  Could you demonstrate how you intend 
to use change.  It looks relatively harmless.  Task object can be 
instantiated with non-string names, but the "name" accessor does a 
"to_s" before returning the value.  Also the "@name" variable isn't used 
within the task class body.  But I'm a little uncomfortable with letting 
go of the concept of string-like names for tasks.  Help me understand.

Second, regarding the delay of dependency calculation, perhaps the 
following will help.

Task actions and dependencies can be declared separately, for example:

   task :a do ... actions go here ... end

   task :a => [... dependencies go here ...]

This opens up some interesting possibilities.  What if we used one task 
to calculate the dependencies of other tasks.  Consider the following 
Rakefile:

     task :default => [:deps, :x]

     def calculate_deps(who)
       puts "SLEEPING ----------------"
       sleep(10)
       puts "AWAKE    ----------------"
       [:y]
     end

     desc "Main Target"
     task :x  do
       puts "DOING X"
     end

     desc "Secondary Task"
     task :y do
       puts "DOING Y"
     end

     desc "Calculate the dependencies"
     task :deps do
       task :x => calculate_deps(:x)
     end

Task x has no dependencies declared in the file.  Task y adds some 
dependencies to x via a long calculation (artificially made long through 
the use of sleep).

With this Rakefile, the rake -T command executes quickly.  E.g.

     $ rake -T
     (in /home/jim/pgm/ruby/rakemisc)
     rake deps  # Calculate the dependencies
     rake x     # Main Target
     rake y     # Secondary Task

If we need to perform task x, then we can explicitly calculate its 
dependencies ...

     $ rake deps x
     (in /home/jim/pgm/ruby/rakemisc)
     SLEEPING ----------------
     AWAKE    ----------------
     DOING Y
     DOING X
     $

Does this help?

-- 
-- Jim Weirich    jim at weirichhouse.org     http://onestepback.org
-----------------------------------------------------------------
"Beware of bugs in the above code; I have only proved it correct,
not tried it." -- Donald Knuth (in a memo to Peter van Emde Boas)