Class: Object

Inherits:
BasicObject
Defined in:
lib/gen_eval.rb

Instance Method Summary collapse

Instance Method Details

#__mirror__ ⇒ Object

end of Ruby 1.9 funcs *



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# File 'ext/gen_eval/gen_eval.c', line 111

VALUE
rb_mirror_object(VALUE context)
{
    VALUE duped_context;
  
#ifdef RUBY_19
    if(TYPE(context) == T_OBJECT)
        duped_context = rb_funcall(rb_cObject, rb_intern("new"), 0);
    else 
        duped_context = rb_funcall(rb_cClass, rb_intern("new"), 0);

#else
    duped_context = rb_funcall(rb_cClass, rb_intern("new"), 0);
#endif    
    
    /* the duped_context shares the context's iv_tbl.
       2 cases: (1) external iv_tbl, (2) local iv_tbl
       
       NOTE: we do not need to save original iv_tbl before replacing it, a brand new Class
       instance does not yet have an iv_tbl (the pointer is set to 0) 
    */
    if(FL_TEST(context, FL_EXIVAR)) 
        RCLASS_IV_TBL(duped_context) = (struct st_table *) rb_generic_ivar_table(context);
    else {
#ifdef RUBY_19
        if(TYPE(context) == T_OBJECT)
            redirect_iv_for_object(context, duped_context);
        else {
            save_m_tbl(duped_context);
            RCLASS_M_TBL(duped_context) = (struct st_table *) RCLASS_M_TBL(context);
            RCLASS_IV_TBL(duped_context) = (struct st_table *) RCLASS_IV_TBL(context);
        }
#else
        save_m_tbl(duped_context);
        RCLASS_M_TBL(duped_context) = (struct st_table *) RCLASS_M_TBL(context);
        RCLASS_IV_TBL(duped_context) = (struct st_table *) RCLASS_IV_TBL(context);
#endif        

        
    }

    /* ensure singleton exists */
    rb_singleton_class(context);
    
    /* set up the class hierarchy for our dup_context */
    KLASS_OF(duped_context) = rb_singleton_class_clone(context);

    return duped_context;
}

#__remove_hidden_self__ ⇒ Object 



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# File 'ext/gen_eval/gen_eval.c', line 9

VALUE
retrieve_hidden_self(VALUE duped_context)
{
    VALUE thread_id, unique_name, hidden_self;
    
    /* retrieve hidden self (if it exists) */
    thread_id = rb_funcall(rb_obj_id(rb_thread_current()), rb_intern("to_s"), 0);
    unique_name = rb_str_plus(rb_str_new2("__hidden_self__"), thread_id);
    hidden_self = rb_ivar_get(duped_context, rb_to_id(unique_name));

    return hidden_self;
}

#__retrieve_hidden_self__ ⇒ Object 



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# File 'ext/gen_eval/gen_eval.c', line 9

VALUE
retrieve_hidden_self(VALUE duped_context)
{
    VALUE thread_id, unique_name, hidden_self;
    
    /* retrieve hidden self (if it exists) */
    thread_id = rb_funcall(rb_obj_id(rb_thread_current()), rb_intern("to_s"), 0);
    unique_name = rb_str_plus(rb_str_new2("__hidden_self__"), thread_id);
    hidden_self = rb_ivar_get(duped_context, rb_to_id(unique_name));

    return hidden_self;
}

#__set_hidden_self__(hidden_self) ⇒ Object 



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# File 'ext/gen_eval/gen_eval.c', line 36

VALUE
set_hidden_self(VALUE duped_context, VALUE hidden_self)
{
    VALUE thread_id, unique_name;
    
    /* generate a unique (thread safe) name for the hidden self  */
    thread_id = rb_funcall(rb_obj_id(rb_thread_current()), rb_intern("to_s"), 0);
    unique_name = rb_str_plus(rb_str_new2("__hidden_self__"), thread_id);

    /* store self in hidden var in duped context */
    rb_ivar_set(duped_context, rb_to_id(unique_name), hidden_self);

    return Qnil;
}

#__unmirror__ ⇒ Object 



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# File 'ext/gen_eval/gen_eval.c', line 161

VALUE
rb_unmirror_object(VALUE duped_context)
{
#ifdef RUBY_19
    if(TYPE(duped_context) == T_OBJECT)
        release_iv_for_object(duped_context);
    else {
        RCLASS_IV_TBL(duped_context) = (struct st_table *) 0;
        restore_m_tbl(duped_context);
    }
#else
    RCLASS_IV_TBL(duped_context) = (struct st_table *) 0;
    restore_m_tbl(duped_context);
#endif

    return Qnil;
}

#capture(&block) ⇒ Object

call-seq:

   capture {| | block }                       => result

Used in conjunction with +gen_eval+. Causes code in block
to be +instance_eval+'d with respect to the receiver of
the +gen_eval+.



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# File 'lib/gen_eval.rb', line 85

def capture(&block)
    raise "block needed" if !block

    hidden_self = self.__retrieve_hidden_self__

    if hidden_self
        result = hidden_self.instance_eval(&block)
    else
        result = yield
    end

    result
end

#gen_eval(*objs, &block) ⇒ Object Also known as: gen_eval_with

call-seq:

   obj.gen_eval {| | block }                       => obj

Works similarly to instance_eval except instance variables are
not looked up in _obj_. All instance methods of +Klass+ are
available but mutators must be wrapped in a +capture+ block.

   class Klass
     attr_reader :age

     def hello(name)
       "hello #{name}"
     end

     def set_age(age)
       capture { 
         @age = age
       }
     end
   end
   k = Klass.new
   @name = "John"
   k.gen_eval { hello(@name) }   #=> "hello John"

   k.gen_eval { set_age(21) }
   k.age #=> 21



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# File 'lib/gen_eval.rb', line 55

def gen_eval(*objs, &block)
  raise "block needed" if !block

  objs = [self] if objs.empty?

  raise "cannot gen_eval on Object" if objs.include?(Object)

  mirror_context = block.__context__.__mirror__
  mirror_context.gen_extend(*objs)
  mirror_context.__set_hidden_self__(self)

  begin
      m = mirror_context.is_a?(Module) ? :module_eval : :instance_eval
      result = mirror_context.send(m, &block)
  ensure
      mirror_context.__remove_hidden_self__
      mirror_context.__unmirror__
  end

  result
end