Forum: Ruby Rake task with variable arguments

Hi,

I want to create a Rails rake task that can accept a varying number of
arguments.  Ideally, I'd like the arguments to be optional, and I'd also
like to be able to specify 1 or more.

So, if I have the rake task my_task, like this:

task :do_something, :arg1 do |t, args|
  puts args.inspect
  # some code goes here
end

I's like to be able to execute this like this:

rake do_something

rake do_something[1]

rake do_something[1, 2, 4]

I'd like args to be an empty array in the first call, a one element
array in the second, and a 3 element array in the third.  I think 0
arguments or 1 is simple -- the way I've written the task above does
this much.  But I don't know how to get it to accept more than 1.  Is
there a way to do this?

Thanks.

I have submitted the following Pull Request to add this functionality:
https://github.com/jimweirich/rake/pull/150.

In analyzing the source, currently there is no place that stores the
argument values not associated with a 'named' argument, so they cannot
be retrieved after parsing.  The patch keeps all the passed-in values
and makes them available via the #to_a method, or just the extra values
via the #extras method (ie, not the values that get associated with
named
arguments.

I have also devised a horrendous hack to get around this current
limitation:

# Prepare the dummy args - supports up to 100 values
vargs = ((0..99).map {|i| ("arg%02d" % i).to_sym})
def vargs.join(*args)
  # This gets used to document the args in rake -T: be descriptive, ie:
  "<target>,<source1>,...,<sourceN>"
end
def vargs.map(&block)
  # This need to return self in order to have the above join work
  # This is only called in the set_arg_names block internally to convert
  # to symbols which it already is; make sure you don't need to use it
  # yourself; if so, use collect instead
  self
end

task :task_name, vargs do |t, args|
  # Pull all the used args out...
  values = args.names.select {|n| !args[n].nil?}.collect {|n| args[n]}
  # Pop out the special values
  target = values.shift
  sources = values

  # Rest of task

end