Module: WithResources

Defined in:
lib/with_resources.rb,
lib/with_resources/version.rb

Defined Under Namespace

Modules: ErrorExt, TopLevel

Constant Summary collapse

VERSION = 
"0.1.0"

Class Method Summary collapse

Class Method Details

.with(allocation, release_method: :close, &block) ⇒ Object 



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# File 'lib/with_resources.rb', line 10

def self.with(allocation, release_method: :close, &block)
  var_names = []
  vars = {}

  allocation_block_path = nil
  allocation_block_lineno = nil

  trace = TracePoint.new(:line, :b_return) do |tp|
    if tp.event == :line && !tp.path.end_with?("lib/with_resources.rb") && allocation_block_path.nil?
      allocation_block_path = tp.path
      allocation_block_lineno = tp.lineno
    end
    if tp.event == :line && tp.path == allocation_block_path && tp.lineno >= allocation_block_lineno
      tp_binding = tp.binding
      tp_variables = tp_binding.local_variables
      if var_names.all?{|resource_var| tp_variables.include?(resource_var) }
        # hit! this block is resource allocation block
        tp_variables.each do |name|
          unless var_names.include?(name)
            var_names << name
          end
        end
      end
    end
    if tp.event == :b_return && tp.path == allocation_block_path && tp.lineno >= allocation_block_lineno
      tp_binding = tp.binding
      var_names.each do |name|
        vars[name] = tp_binding.local_variable_get(name)
      end
    end
  end

  error = nil
  return_value = nil
  begin
    trace.enable do
      allocation.call
    end
    return_value = block.call(*vars.values)
  rescue => e
    error = e
    error.extend(ErrorExt)
  ensure
    vars.values.reverse.each do |v|
      if v.respond_to?(release_method)
        begin
          v.send(release_method)
        rescue => e
          if error
            error.suppressed << e
          else
            error = e
            error.extend(ErrorExt)
          end
        end
      end
    end
  end
  raise error if error
  return_value
end