Class: CShadow::ObjectAttribute

Inherits:
Attribute show all
Defined in:
lib/cgen/attribute.rb

Overview

There are two kinds of object attributes. Both refer to Ruby objects and can be typed or untyped. This one is less optimized but cat refer to arbitrary ruby objects.

The syntax for adding an object attribute to a class is simple. The following code adds three object attributes, one untyped and two typed:

class A
  include CShadow
  shadow_attr_accessor :obj => Object, :sym => Symbol, :ary => Array
end

(See CShadow for variations on #shadow_attr_accessor.)

Assignment to obj performs no type checking. Assignment to sym raises a TypeError unless the object assigned is a Symbol or nil. Similarly ary must always be an Array or nil. Type checking always allows nil in addition to the specified type. In each case, the attribute is initialized to nil.

The referenced Ruby object is marked to protect it from the garbage collector.

Instance Attribute Summary

Attributes inherited from Attribute

#cdecl, #check, #cvar, #dump, #free, #init, #load, #mark, #owner_class, #persists, #reader, #var, #writer

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Attribute

inherited

Constructor Details

#initialize(*args) ⇒ ObjectAttribute

Returns a new instance of ObjectAttribute.



132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
 
# File 'lib/cgen/attribute.rb', line 132

def initialize(*args)
  super
  @class = @match
  
  @cvar = @var
  @cdecl = "VALUE #{@cvar}; // #{@class}"
  
  @init = "shadow->#{@cvar} = Qnil" # otherwise, it's Qfalse == 0
  @reader = "result = shadow->#{@cvar}"
  @writer = "shadow->#{@cvar} = arg"
  @check = @class unless @class == Object
  @mark = "rb_gc_mark(shadow->#{@cvar})"
  
  @dump = "rb_ary_push(result, shadow->#{@cvar})"
  @load = "shadow->#{@cvar} = rb_ary_shift(from_array)"
end

Class Method Details

.match(decl) ⇒ Object 



126
127
128
 
# File 'lib/cgen/attribute.rb', line 126

def ObjectAttribute.match decl
  decl if decl.is_a? Class
end

Instance Method Details

#inspect ⇒ Object 



149
150
151
 
# File 'lib/cgen/attribute.rb', line 149

def inspect
  %{<#{self.class} #{@cvar} => #{@class.inspect}>}
end

#target_class ⇒ Object 



130
 
# File 'lib/cgen/attribute.rb', line 130

def target_class; @class; end