Class: Binding

Inherits:
Object show all
Defined in:
lib/nano/binding/of_caller.rb,
lib/nano/binding/eval.rb,
lib/nano/binding/self.rb,
lib/nano/binding/%5B%5D.rb,
lib/nano/binding/called.rb,
lib/nano/binding/caller.rb,
lib/nano/binding/__DIR__.rb,
lib/nano/binding/__FILE__.rb,
lib/nano/binding/__LINE__.rb,
lib/nano/binding/%5B%5D%3D.rb,
lib/nano/binding/call_stack.rb,
lib/nano/binding/defined%3F.rb,
lib/nano/binding/method_name.rb,
lib/nano/binding/%3A%3Aof_caller.rb,
lib/nano/binding/local_variables.rb

Overview

end

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.of_caller(&block) ⇒ Object

This method returns the binding of the method that called your method. It will raise an Exception when you’re not inside a method.

It’s used like this:

def inc_counter(amount = 1)
  Binding.of_caller do |binding|
    # Create a lambda that will increase the variable 'counter'
    # in the caller of this method when called.
    inc = eval("lambda { |arg| counter += arg }", binding)
    # We can refer to amount from inside this block safely.
    inc.call(amount)
  end
  # No other statements can go here. Put them inside the block.
end
counter = 0
2.times { inc_counter }
counter # => 2

Binding.of_caller must be the last statement in the method. This means that you will have to put everything you want to do after the call to Binding.of_caller into the block of it. This should be no problem however, because Ruby has closures. If you don’t do this an Exception will be raised. Because of the way that Binding.of_caller is implemented it has to be done this way.



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# File 'lib/nano/binding/of_caller.rb', line 44

def Binding.of_caller(&block)
  old_critical = Thread.critical
  Thread.critical = true
  count = 0
  cc, result, error, extra_data = Continuation.create(nil, nil)
  error.call if error

  tracer = lambda do |*args|
    type, context, extra_data = args[0], args[4], args
    if type == "return"
      count += 1
      # First this method and then calling one will return --
      # the trace event of the second event gets the context
      # of the method which called the method that called this
      # method.
      if count == 2
        # It would be nice if we could restore the trace_func
        # that was set before we swapped in our own one, but
        # this is impossible without overloading set_trace_func
        # in current Ruby.
        set_trace_func(nil)
        cc.call(eval("binding", context), nil, extra_data)
      end
    elsif type == "line" then
      nil
    elsif type == "c-return" and extra_data[3] == :set_trace_func then
      nil
    else
      set_trace_func(nil)
      error_msg = "Binding.of_caller used in non-method context or " +
        "trailing statements of method using it aren't in the block."
      cc.call(nil, lambda { raise(ArgumentError, error_msg) }, nil)
    end
  end

  unless result
    set_trace_func(tracer)
    return nil
  else
    Thread.critical = old_critical
    case block.arity
      when 1 then yield(result)
      else yield(result, extra_data)
    end
  end
end

Instance Method Details

#[](x) ⇒ Object

Returns the value of some variable.

a = 2
binding["a"]  #=> 2



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# File 'lib/nano/binding/%5B%5D.rb', line 8

def []( x )
  eval( x.to_s )
end

#[]=(l, v) ⇒ Object

Set the value of a local variable.

binding["a"] = 4
a  #=> 4



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# File 'lib/nano/binding/%5B%5D%3D.rb', line 8

def []=( l, v )
  eval( "proc {|v| #{l} = v}").call( v )
end

#__DIR__ ⇒ Object

returns line number



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# File 'lib/nano/binding/__DIR__.rb', line 4

def __DIR__
  eval( "File.dirname(__FILE__)" )
end

#__FILE__ ⇒ Object

returns file name



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# File 'lib/nano/binding/__FILE__.rb', line 4

def __FILE__
  eval( "__FILE__" )
end

#__LINE__ ⇒ Object

returns line number



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# File 'lib/nano/binding/__LINE__.rb', line 4

def __LINE__
  eval( "__LINE__" )
end

#call_stack(level = 1) ⇒ Object

Returns the call stack, in array format.



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# File 'lib/nano/binding/call_stack.rb', line 5

def call_stack( level = 1 )
  eval( "call_stack( #{level} )" )
end

#called ⇒ Object

Retreive the current running method.

def tester; p called; end
tester  #=> :tester



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# File 'lib/nano/binding/called.rb', line 8

def called
  name = /\`([^\']+)\'/.match(caller(1).first)[1]
  return name.to_sym
end

#caller(skip = 0) ⇒ Object

Returns the call stack, same format as Kernel#caller()



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# File 'lib/nano/binding/caller.rb', line 4

def caller( skip = 0 )
  eval( "caller( #{skip} )" )
end

#defined?(x) ⇒ Boolean

Returns the nature of something, nil if that thing is not defined.

Returns:

  • (Boolean) 


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# File 'lib/nano/binding/defined%3F.rb', line 4

def defined?( x )
  eval( "defined? #{x}" )
end

#eval(str) ⇒ Object

Evaluate a Ruby source code string (or block) in the binding context



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# File 'lib/nano/binding/eval.rb', line 3

def eval( str ) #='', &blk )
  #if block_given?
  #  Kernel.eval( self, &blk )
  #elsif str
    Kernel.eval( str, self )
  #end
end

#local_variables ⇒ Object

Returns the local variables defined in the binding context

a = 2
binding.local_variables  #=> ["a"]



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# File 'lib/nano/binding/local_variables.rb', line 8

def local_variables()
  eval( "local_variables" )
end

#method_name ⇒ Object

There is a lot of debate on what to call this. method_name differs from #called only by the fact that it returns a string, rather then a symbol.

def tester; p method_name; end
tester  #=> "tester"



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# File 'lib/nano/binding/method_name.rb', line 10

def method_name
  name = /\`([^\']+)\'/.match(caller(1).first)[1]
  return name
end

#self ⇒ Object

Returns the self in the binding context.



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# File 'lib/nano/binding/self.rb', line 7

def self()
  @self ||= eval( "self" )
  @self
end