module DSLKit::InstanceExec

def instance_exec(*args, &block)

the block.
executes _block_ in the context of this object while parsing *args into
This is a pure ruby implementation of Ruby 1.9's instance_exec method. It 
def instance_exec(*args, &block)
  instance = self
  id = instance_exec_fetch_symbol
  InstanceExec.module_eval do
    begin
      define_method id, block
      instance.__send__ id, *args
    ensure
      remove_method id if method_defined?(id)
    end
  end
ensure
  InstanceExec.pool << id
end

def instance_exec_fetch_symbol

available create a new one, that will be pushed into the pool later.
Fetch a symbol from a pool in thread save way. If no more symbols are 
def instance_exec_fetch_symbol
  @@mutex.synchronize do
    if InstanceExec.pool.empty?
      InstanceExec.count += 1
      symbol = :"__instance_exec_#{InstanceExec.count}__"
    else
      symbol = InstanceExec.pool.shift
    end
    return symbol
  end
end