Class: MonkeyShield

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

Defined Under Namespace

Classes: MethodDefinedInModuleCallsSuper, NoContextError

Constant Summary collapse

VERSION = 
"0.1.0"
UNIQUE_METHOD_NAMES = 
{}
CONTEXT_WRAPPED_METHODS = 
Hash.new{|h,k| h[k] = [] }

Class Method Summary collapse

Class Method Details

.alias_method_added_hooks ⇒ Object 



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# File 'lib/monkey_shield.rb', line 148

def alias_method_added_hooks
  return  if @method_added_hooks_aliased

  # TODO; catch method_added being added and automatically wrap it
  # these list must contain all classes any other library might override method_added on (eg. BlankSlate classes)
  klasses = [Module, (class << Object; self; end), (class << Kernel; self; end)]
  klasses.each do |klass|
    klass.class_eval do
      if method_defined? :method_added
        old_method_added = MonkeyShield.unique_method_name(:method_added)
        alias_method old_method_added, :method_added
      end

      if method_defined? :singleton_method_added
        old_singleton_method_added = MonkeyShield.unique_method_name(:singleton_method_added)
        alias_method old_singleton_method_added, :singleton_method_added
      end

      class_eval <<-EOF, __FILE__, __LINE__
        def __MONKEY__method_added__proxy method_name
          __MONKEY__method_added(self, method_name)
          #{old_method_added && "#{old_method_added} method_name"}
        end

        def __MONKEY__singleton_method_added__proxy method_name
          __MONKEY__method_added((class<<self;self;end), method_name)
          #{old_singleton_method_added && "#{old_singleton_method_added} method_name"}
        end
      EOF

      alias_method :method_added, :__MONKEY__method_added__proxy
      alias_method :singleton_method_added, :__MONKEY__singleton_method_added__proxy
    end
  end


  @method_added_hooks_aliased = true
end

.context_stack ⇒ Object 



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# File 'lib/monkey_shield.rb', line 206

def context_stack
  s = Thread.current[:__MONKEY__method_context] and s.dup
end

.context_switch_for(klass, method_name) ⇒ Object 



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# File 'lib/monkey_shield.rb', line 114

def context_switch_for klass, method_name
  klass.class_eval do
    class_eval <<-EOF, __FILE__, __LINE__
      def #{tmp_name = MonkeyShield.temp_method_name} *args, &blk
        raise NoContextError  if ! MonkeyShield.current_context
        __send__(MonkeyShield.prefix_with_context(#{method_name.inspect}, MonkeyShield.current_context), *args, &blk)
      end
    EOF
    alias_method method_name, tmp_name
    remove_method tmp_name
  end
end

.current_context ⇒ Object 



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# File 'lib/monkey_shield.rb', line 210

def current_context
  s = Thread.current[:__MONKEY__method_context] and s.last
end

.hook_method_added(hook = true, &blk) ⇒ Object 



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# File 'lib/monkey_shield.rb', line 239

def hook_method_added(hook = true, &blk)
  orig, @hook_method_added = @hook_method_added, hook
  yield
ensure
  @hook_method_added = orig
end

.hook_method_added? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/monkey_shield.rb', line 250

def hook_method_added?
  @hook_method_added
end

.hook_module_function(&blk) ⇒ Object 



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# File 'lib/monkey_shield.rb', line 187

def hook_module_function(&blk)
  old_module_function = MonkeyShield.unique_method_name(:module_function)
  Module.class_eval do
    alias_method old_module_function, :module_function
    alias_method :module_function, :__MONKEY__module_function
  end

  yield
ensure
  Module.class_eval { alias_method :module_function, old_module_function }
end

.ignore_method_added(&blk) ⇒ Object 



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# File 'lib/monkey_shield.rb', line 246

def ignore_method_added(&blk)
  hook_method_added false, &blk
end

.in_context(context, &blk) ⇒ Object 



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# File 'lib/monkey_shield.rb', line 199

def in_context(context, &blk)
  push_context context
  yield
ensure
  pop_context
end

.pop_context ⇒ Object 



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# File 'lib/monkey_shield.rb', line 218

def pop_context
  s = Thread.current[:__MONKEY__method_context] and s.pop
end

.prefix_with_context(method_name, context) ⇒ Object 



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# File 'lib/monkey_shield.rb', line 227

def prefix_with_context(method_name, context)
  "__MONKEY__context__#{context}__#{method_name}" 
end

.push_context(context) ⇒ Object 



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# File 'lib/monkey_shield.rb', line 214

def push_context(context)
  (Thread.current[:__MONKEY__method_context] ||= []).push context
end

.reset! ⇒ Object 



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# File 'lib/monkey_shield.rb', line 109

def reset!
  CONTEXT_WRAPPED_METHODS.clear
  UNIQUE_METHOD_NAMES.clear
end

.set_default_context_for(klass, method_name, context) ⇒ Object 



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# File 'lib/monkey_shield.rb', line 127

def set_default_context_for klass, method_name, context
  context_switched_name = "__context_switch__#{MonkeyShield.unique}__#{method_name}"
  klass.class_eval do
    alias_method context_switched_name, method_name
    class_eval <<-EOF, __FILE__, __LINE__
      def #{tmp_name = MonkeyShield.temp_method_name} *args, &blk
        if ! MonkeyShield.current_context
          need_pop = true
          MonkeyShield.push_context #{context.inspect}
        end

        __send__(#{context_switched_name.inspect}, *args, &blk)
      ensure
        MonkeyShield.pop_context  if need_pop
      end
    EOF
    alias_method method_name, tmp_name
    remove_method tmp_name
  end
end

.temp_method_name ⇒ Object 



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# File 'lib/monkey_shield.rb', line 235

def temp_method_name
  "__MONKEY__temp_method__#{unique}"
end

.unique ⇒ Object 



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# File 'lib/monkey_shield.rb', line 222

def unique
  $unique_counter ||= 0
  $unique_counter += 1
end

.unique_method_name(method_name) ⇒ Object 



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# File 'lib/monkey_shield.rb', line 231

def unique_method_name(method_name)
  "__MONKEY__unique_method__#{unique}__#{method_name}"
end

.warnings ⇒ Object 



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# File 'lib/monkey_shield.rb', line 254

def warnings
  if Object.const_defined? :BasicObject and ! $LOADED_FEATURES.grep(/facets.+basic.?object/).empty?
    raise "BasicObject on Facets <= 2.4.1 will BREAK this library, use alternative blankslate/basicobject class"
  end
end

.wrap_method_with_context(klass, method_name, context) ⇒ Object 



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# File 'lib/monkey_shield.rb', line 71

def wrap_method_with_context(klass, method_name, context)
  klass.class_eval do
    visibility = instance_method_visibility method_name 
    return  if ! visibility  # something else removed the method already, wth!

    method_name_with_context = MonkeyShield.prefix_with_context(method_name, context)
    unique_method_name = MonkeyShield.unique_method_name(method_name)

    alias_method method_name_with_context, method_name
    alias_method unique_method_name, method_name
    private method_name_with_context, unique_method_name

    UNIQUE_METHOD_NAMES[ [self, method_name] ] = unique_method_name
    CONTEXT_WRAPPED_METHODS[ [self, method_name] ] << context

    class_eval <<-EOF, __FILE__, __LINE__
      def #{tmp_name = MonkeyShield.temp_method_name} *args, &blk
        MonkeyShield.in_context #{context.inspect} do
          __send__(#{unique_method_name.inspect}, *args, &blk)
        end
      rescue NoMethodError
        if $!.message =~ /super: no superclass method `(.+?)'/
          raise MonkeyShield::MethodDefinedInModuleCallsSuper, "Please add #{self.name}##{method_name} to the exceptions list!"
        end

        raise
      end
    EOF
    alias_method method_name, tmp_name
    remove_method tmp_name

    send visibility, method_name
  end
rescue
  puts "failed to wrap #{klass.name}##{method_name}: #{$!}"
  puts $!.backtrace.join("\n")
end

.wrap_with_context(context, exceptions = [], &blk) ⇒ Object 



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# File 'lib/monkey_shield.rb', line 49

def wrap_with_context(context, exceptions = [], &blk) 
  Module.class_eval do
    define_method :__MONKEY__method_added do |klass, method_name|
      return  unless MonkeyShield.hook_method_added?
      return  if exceptions.include? method_name or exceptions.include? "#{klass.name}##{method_name}" or
                 exceptions.any? {|ex| ex.is_a? Regexp and ex =~ method_name.to_s }

      MonkeyShield.ignore_method_added { MonkeyShield.wrap_method_with_context(klass, method_name, context) }
    end
  end

  MonkeyShield.alias_method_added_hooks

  MonkeyShield.hook_module_function do
    MonkeyShield.hook_method_added do
      yield
    end
  end

  MonkeyShield.warnings
end