Class: Class

### Home Classes Methods

### In Files

- lib/extlib/class.rb

### Parent

Object

### Methods

- #cattr_accessor
- #cattr_reader
- #cattr_writer
- #class_inheritable_accessor
- #class_inheritable_reader
- #class_inheritable_writer

### Files

- LICENSE
- README.rdoc

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# Class

Allows attributes to be shared within an inheritance hierarchy, but where each descendant gets a copy of their parents' attributes, instead of just a pointer to the same. This means that the child can add elements to, for example, an array without those additions being shared with either their parent, siblings, or children, which is unlike the regular class-level attributes that are shared across the entire hierarchy.

### Public Instance Methods

cattr_accessor(*syms) click to toggle source

Defines class-level (and optionally instance-level) attribute accessor.

@param *syms<Array[*to_s, Hash{:instance_writer => Boolean}]> Array of attributes to define accessor for. @option syms :instance_writer<Boolean> if true, instance-level attribute writer is defined. @return [Array<to_s>] List of attributes that were made into accessors

@api public

    # File lib/extlib/class.rb, line 96
    def cattr_accessor(*syms)
      cattr_reader(*syms)
      cattr_writer(*syms)
    end

cattr_reader(*syms) click to toggle source

Defines class-level and instance-level attribute reader.

@param [*syms<Array] Array of attributes to define reader for. @return [Array<to_s>] List of attributes that were made into cattr_readers

@api public

@todo Is this inconsistent in that it does not allow you to prevent

    an instance_reader via :instance_reader => false

    # File lib/extlib/class.rb, line 40
    def cattr_reader(*syms)
      syms.flatten.each do |sym|
        next if sym.is_a?(Hash)
        class_eval(        unless defined? @@#{sym}          @@#{sym} = nil        end        def self.#{sym}          @@#{sym}        end        def #{sym}          @@#{sym}        end, __FILE__, __LINE__ + 1)
      end
    end

cattr_writer(*syms) click to toggle source

Defines class-level (and optionally instance-level) attribute writer.

@param [Array<*to_s, Hash{:instance_writer => Boolean}>] Array of attributes to define writer for. @option syms :instance_writer<Boolean> if true, instance-level attribute writer is defined. @return [Array<to_s>] List of attributes that were made into cattr_writers

@api public

    # File lib/extlib/class.rb, line 66
    def cattr_writer(*syms)
      options = syms.last.is_a?(Hash) ? syms.pop : {}
      syms.flatten.each do |sym|
        class_eval(        unless defined? @@#{sym}          @@#{sym} = nil        end        def self.#{sym}=(obj)          @@#{sym} = obj        end, __FILE__, __LINE__ + 1)

        unless options[:instance_writer] == false
          class_eval(          def #{sym}=(obj)            @@#{sym} = obj          end, __FILE__, __LINE__ + 1)
        end
      end
    end

class_inheritable_accessor(*syms) click to toggle source

Defines class-level inheritable attribute accessor. Attributes are available to subclasses, each subclass has a copy of parent's attribute.

@param *syms<Array[*to_s, Hash{:instance_writer => Boolean}]> Array of attributes to

    define inheritable accessor for.

@option syms :instance_writer<Boolean> if true, instance-level inheritable attribute writer is defined. @return [Array<to_s>] An Array of attributes turned into inheritable accessors.

@api public

    # File lib/extlib/class.rb, line 175
    def class_inheritable_accessor(*syms)
      class_inheritable_reader(*syms)
      class_inheritable_writer(*syms)
    end

class_inheritable_reader(*ivars) click to toggle source

Defines class-level inheritable attribute reader. Attributes are available to subclasses, each subclass has a copy of parent's attribute.

@param *syms> Array of attributes to define inheritable reader for. @return [Array<to_s>] Array of attributes converted into inheritable_readers.

@api public

@todo Do we want to block instance_reader via :instance_reader => false @todo It would be preferable that we do something with a Hash passed in

    (error out or do the same as other methods above) instead of silently
    moving on). In particular, this makes the return value of this function
    less useful.

    # File lib/extlib/class.rb, line 114
    def class_inheritable_reader(*ivars)
      instance_reader = ivars.pop[:reader] if ivars.last.is_a?(Hash)

      ivars.each do |ivar|
        self.class_eval         def self.#{ivar}          return @#{ivar} if defined?(@#{ivar})          return nil      if self.object_id == #{self.object_id}          ivar = superclass.#{ivar}          return nil if ivar.nil?          @#{ivar} = ivar.try_dup        end, __FILE__, __LINE__ + 1

        unless instance_reader == false
          self.class_eval           def #{ivar}            self.class.#{ivar}          end, __FILE__, __LINE__ + 1
        end
      end
    end

class_inheritable_writer(*ivars) click to toggle source

Defines class-level inheritable attribute writer. Attributes are available to subclasses, each subclass has a copy of parent's attribute.

@param *syms<Array[*to_s, Hash{:instance_writer => Boolean}]> Array of attributes to

    define inheritable writer for.

@option syms :instance_writer<Boolean> if true, instance-level inheritable attribute writer is defined. @return [Array<to_s>] An Array of the attributes that were made into inheritable writers.

@api public

@todo We need a style for class_eval <<-HEREDOC. I'd like to make it

    class_eval(<<-RUBY, __FILE__, __LINE__), but we should codify it somewhere.

    # File lib/extlib/class.rb, line 150
    def class_inheritable_writer(*ivars)
      instance_writer = ivars.pop[:instance_writer] if ivars.last.is_a?(Hash)
      ivars.each do |ivar|
        self.class_eval         def self.#{ivar}=(obj)          @#{ivar} = obj        end, __FILE__, __LINE__ + 1
        unless instance_writer == false
          self.class_eval           def #{ivar}=(obj) self.class.#{ivar} = obj end, __FILE__, __LINE__ + 1
        end
      end
    end

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