Class: Rod::Property::SingularAssociation

Inherits:
Base
  • Object
show all
Defined in:
lib/rod/property/singular_association.rb

Overview

This class defines the has_one (singular association) property. A has_one property has to define its name.

Instance Attribute Summary

Attributes inherited from Base

#name, #options

Instance Method Summary collapse

Methods inherited from Base

#copy, #define_finders, #difference, #has_index?, #index, #reset_index

Constructor Details

#initialize(klass, name, options = {}) ⇒ SingularAssociation

Creates new singular association associated with klass, with given name and options. Valid options are:

  • :class_name - the name of the class (as String) associated with this class

  • :polymorphic - if set to true the association is polymorphic (allows to access objects of different classes via this association).



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# File 'lib/rod/property/singular_association.rb', line 15

def initialize(klass,name,options={})
  super(klass,name,options)
end

Instance Method Details

#association? ⇒ Boolean

Predicate indicating that this property is an association.

Returns:

  • (Boolean) 


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# File 'lib/rod/property/singular_association.rb', line 25

def association?
  true
end

#define_c_accessors(builder) ⇒ Object

Defines the accessor of the association’s constituents (C struct field/fields that hold the association data).



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# File 'lib/rod/property/singular_association.rb', line 60

def define_c_accessors(builder)
  field_reader(@name,@klass.struct_name,c_type(:ulong),builder)
  field_writer(@name,@klass.struct_name,c_type(:ulong),builder)
  if polymorphic?
    field_reader("#{@name}__class",@klass.struct_name,c_type(:ulong),builder)
    field_writer("#{@name}__class",@klass.struct_name,c_type(:ulong),builder)
  end
end

#define_getter ⇒ Object

Defines the getter of the Ruby class which corresponds to this association.



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# File 'lib/rod/property/singular_association.rb', line 76

def define_getter
  # optimization
  name = @name.to_s
  property = self
  class_name =
    if @options[:class_name]
      @options[:class_name]
    else
      "#{@klass.scope_name}::#{name.camelcase}"
    end
  klass = options[:polymorphic] ? nil : class_name.constantize
  @klass.send(:define_method,name) do
    value = instance_variable_get("@#{name}")
    if value.nil?
      return nil if self.new?
      rod_id = send("_#{name}",@rod_id)
      # the indices are shifted by 1, to leave 0 for nil
      if rod_id == 0
        value = nil
      else
        if property.polymorphic?
          klass = Model.get_class(send("_#{name}__class",@rod_id))
        end
        value = klass.find_by_rod_id(rod_id)
      end
      # avoid change tracking
      instance_variable_set("@#{name}",value)
    end
    value
  end
end

#define_setter ⇒ Object

Defines the settor of the Ruby class which corresponds to this association.



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# File 'lib/rod/property/singular_association.rb', line 109

def define_setter
  # optimization
  name = @name.to_s
  @klass.send(:define_method,"#{name}=") do |value|
    old_value = send(name)
    send("#{name}_will_change!") unless old_value == value
    instance_variable_set("@#{name}", value)
    value
  end
end

#field? ⇒ Boolean

Predicate indicating that this property is a field.

Returns:

  • (Boolean) 


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# File 'lib/rod/property/singular_association.rb', line 20

def field?
  false
end

#layout ⇒ Object

Returns the memory layout of the C struct fields that correspond to this association.



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# File 'lib/rod/property/singular_association.rb', line 122

def layout
  unless polymorphic?
    "#{@name}[value:#{sizeof(:ulong)}]"
  else
    "#{@name}[value:#{sizeof(:ulong)}+" +
      "class:#{sizeof(:ulong)}]"
  end
end

#metadata ⇒ Object

Returns the metadata of the association in form of a hash.



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# File 'lib/rod/property/singular_association.rb', line 45

def metadata
  @options.dup
end

#plural? ⇒ Boolean

Predicate indicating that this property is not a plural association.

Returns:

  • (Boolean) 


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# File 'lib/rod/property/singular_association.rb', line 35

def plural?
  false
end

#polymorphic? ⇒ Boolean

Predicate indicating that this property is polymorphic.

Returns:

  • (Boolean) 


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# File 'lib/rod/property/singular_association.rb', line 40

def polymorphic?
  @options[:polymorphic]
end

#seal_c_accessors ⇒ Object

Make the C accessors private.



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# File 'lib/rod/property/singular_association.rb', line 70

def seal_c_accessors
  @klass.send(:private,"_#{@name}")
  @klass.send(:private,"_#{@name}=")
end

#singular? ⇒ Boolean

Predicate indicating that this property is a singular association.

Returns:

  • (Boolean) 


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# File 'lib/rod/property/singular_association.rb', line 30

def singular?
  true
end

#to_c_struct ⇒ Object

Converts the association to fields in a C struct.



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# File 'lib/rod/property/singular_association.rb', line 50

def to_c_struct
  result = "  #{c_type(:ulong)} #{@name};\n"
  if polymorphic?
    result += "  #{c_type(:ulong)} #{@name}__class;\n"
  end
  result
end