Class: MySQLNoIo::WrapStack

Inherits:
Object
  • Object
show all
Defined in:
lib/mysqlnoio/wrap_stack.rb

Overview

A WrapStack collects a series of Wraps, and runs their #execute commands inside one another.

Example: stack = MySQLNoIo::WrapStack.new()a

wrapFoo = Wrap::Foo.new() wrapBar = Wrap::Bar.new()

stack.add_stack wrapFoo stack.add_stack wrapBar stack.execute do puts "hi" end

Is identical to: wrapFoo.execute do wrapBar.execute do puts "hi" end end

Instance Method Summary collapse

Constructor Details

#initialize ⇒ WrapStack

Returns a new instance of WrapStack.



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# File 'lib/mysqlnoio/wrap_stack.rb', line 26

def initialize
  @wraps = []
end

Instance Method Details

#add_wrap(wrap) ⇒ TrueClass

Add a layer to wrap around the execution of the command

Parameters:

  • wrapper to add to the stack

Returns:

Raises:

  • if the wrapper is not sufficient



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# File 'lib/mysqlnoio/wrap_stack.rb', line 36

def add_wrap wrap
  unless wrap.respond_to?('execute')
    raise MySQLNoIo::Errors::ArgumentError.new('Wrap must respond to #execute and accept a block.')
  end

  @wraps << wrap

  true
end

#execute(&block) ⇒ Object

Execute your bit of code from within the safety and comfort of the wrappers appended to the stack.



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# File 'lib/mysqlnoio/wrap_stack.rb', line 48

def execute &block
  # Brace yourself.
  #
  # This next bit of code creates a nested lamda like the WrapStack
  # describes.
  deep_proc = @wraps.reverse.inject(block) do |deep_proc, layer|
    Proc.new do
      layer.execute do
        deep_proc.call
      end
    end
  end

  deep_proc.call
end