outdated howtos

howto.txt

h2. Use an older version of Tap (or any gem)

Rubygems makes it very easy to use an older version of tap:

  <notextile><pre><code>% tap _version_ ...</pre></code></notextile>

As you can see, all you have to do is specify the version in the first argument.  This trick can also be useful for fixing the version of tap used if it gets called from another process.

  <notextile><pre><code>% tap _0.10.3_
usage: tap <command> {options} [args]

examples:
  tap generate root .                  # generates a root dir
  tap run taskname --option input      # runs the 'taskname' task

help:
  tap help                             # prints this help
  tap command --help                   # prints help for 'command'

available commands:
  console
  destroy
  generate
  help
  run
  
version 0.10.3 -- http://tap.rubyforge.org</pre></code></notextile>

h2. Enter newlines, escape characters into configurations

Sometimes you need escaped characters in a configuration, for instance when formatting csv output.  To do so, use the string validation then write them in as you would in a script:
  
  <notextile><pre><code># StringConfig::manifest
class StringConfig < Tap::Task
  config :a, "", &c.string
  config :b, "", &c.string
  config :c, "", &c.string
  config :d, "", &c.string
  config :e, "", &c.string

  def process
    [:a,:b,:c,:d,:e].each do |key|
      type = case config[key]
      when "\n" then 'newline'
      when '\n' then 'backslash, n'
      else 'other'
      end
    
      puts "#{key}: #{type}"
    end
  end
end</pre></code></notextile>

Now check out what happens:

  % tap run -- string_config --a '\n' --b '\\n' --c "\n" --d "\\n" --e "\\\n"
  a: newline
  b: backslash, n
  c: newline
  d: newline
  e: backslash, n