Remove duplication from rake tasks

Question

I have three rake tasks that modify an instance variable and then call the task :find, This is the Rakefile:

@tags = ['OPTIMIZE', 'TODO', 'FIXME']

task :optimize do
   @tags = ['OPTIMIZE']
   Rake::Task["find"].invoke
end

task :todo do
   @tags = ['TODO']
   Rake::Task["find"].invoke
end

task :fixme do
   @tags = ['FIXME']
   Rake::Task["find"].invoke
end

task :find do
   # finds words depending on @tags
end

I would like to remove duplication from the Rakefile and make it more concise. How can I simplify (or combine) the :optimize, :todo, :fixme tasks in this Rakefile?

Answer 1

Rake tasks can take arguments, so instead of relying on an instance variable you can pass the tags in:

TAGS = ['OPTIMIZE', 'TODO', 'FIXME']

task :find, [:tags] do |task, args|
  # command lines can't pass an array, afaik; so if we pass the
  # tags in, we'll need them as a space separated list
  tags = if args[:tags]
           args[:tags].split(' ')
         else
           TAGS
         end

  puts "finding all tags marked: #{tags.inspect}"
end

and then on the command line:

% rake find[TODO OPTIMIZE] # may need escaped: rake find\[TODO\ OPTIMIZE\]
finding all tags marked: ["TODO", "OPTIMIZE"]
% rake find                  
finding all tags marked: ["OPTIMIZE", "TODO", "FIXME"]

and then, if you still want named tasks as aliases, passing certain arguments, you can pass them in through invoke:

TAGS.each do |tag|
  task tag.downcase.to_sym do
    Rake::Task["find"].invoke(tag)
  end
end

and calling them:

% rake todo
finding all tags marked: ["TODO"]
% rake fixme   
finding all tags marked: ["FIXME"]
% rake optimize
finding all tags marked: ["OPTIMIZE"]