Dynamically assigning class constants

ruby-talk
1

Hi folks,

I have a class definition as follows:

class Level
    attr_reader :name, :rank
    def initialize( name, rank )
      @name, @rank = name, rank
    end
       TRACE = Comparable.new( :TRACE, 1000 )
    DEBUG = Comparable.new( :DEBUG, 2000 )
    INFO = Comparable.new( :INFO, 3000 )
    # etc
end

and I'd like to define the constants in a more ruby-esque way; something like:

  class Level
    attr_reader :name, :rank
    def initialize( name, rank )
      @name, @rank = name, rank
    end
       %w{TRACE DEBUG INFO CHANGE WARN ERROR FATAL}.each_with_index do |name,i|
      clever_dynamic_hackery( name, Comparable.new( name.to_sym, i*1000 ) )
    end
     end

but I don't know what that clever_dyanamic_hackery method should actually be. Any one want to show me the light?

Cheers,
Pete

2

Apologies, s/Comparable/Level/ in the example code.

Pete Hodgson wrote:

···

Hi folks,

I have a class definition as follows:

class Level
    attr_reader :name, :rank
    def initialize( name, rank )
      @name, @rank = name, rank
    end

    TRACE = Comparable.new( :TRACE, 1000 )
    DEBUG = Comparable.new( :DEBUG, 2000 )
    INFO = Comparable.new( :INFO, 3000 )
    # etc
end

and I'd like to define the constants in a more ruby-esque way; something
like:

  class Level
    attr_reader :name, :rank
    def initialize( name, rank )
      @name, @rank = name, rank
    end

    %w{TRACE DEBUG INFO CHANGE WARN ERROR FATAL}.each_with_index do |name,i|
      clever_dynamic_hackery( name, Comparable.new( name.to_sym, i*1000 ) )
    end

  end

but I don't know what that clever_dyanamic_hackery method should
actually be. Any one want to show me the light?

Cheers,
Pete

3

there might be a method for specifically creating constants,but if not
you could always do something like this:

module_eval("#{name} = #{i*1000}", __FILE__, __LINE__)

···

On Fri, Sep 5, 2008 at 4:44 PM, Pete Hodgson <phodgson@lyris.com> wrote:

Apologies, s/Comparable/Level/ in the example code.

Pete Hodgson wrote:

Hi folks,

I have a class definition as follows:

class Level
   attr_reader :name, :rank
   def initialize( name, rank )
     @name, @rank = name, rank
   end

   TRACE = Comparable.new( :TRACE, 1000 )
   DEBUG = Comparable.new( :DEBUG, 2000 )
   INFO = Comparable.new( :INFO, 3000 )
   # etc
end

and I'd like to define the constants in a more ruby-esque way; something
like:

class Level
   attr_reader :name, :rank
   def initialize( name, rank )
     @name, @rank = name, rank
   end

   %w{TRACE DEBUG INFO CHANGE WARN ERROR FATAL}.each_with_index do
>name,i|
     clever_dynamic_hackery( name, Comparable.new( name.to_sym, i*1000 ) )
   end

end

but I don't know what that clever_dyanamic_hackery method should
actually be. Any one want to show me the light?

Cheers,
Pete

4

module M
  %w(FOO BAR BAZ).each do |c|
    const_set(c, 1)
  end
end

5

Wonderful, thank you Xavier!

Xavier Noria wrote:

···

module M
  %w(FOO BAR BAZ).each do |c|
    const_set(c, 1)
  end
end