Ruby: How to set instance variables from a class method? - ruby

Question

I'm not sure that's the right title for this question, but I don't know how else to ask it. I have classes that need to be registered globally so they can be called later. I have most of it working except for a very important part. When the child inherits from the parent class, it registers a new instance, but when the on_message class method is called, I can't figure out how to set the instance variables that I need.
class MyExtension < ExtensionBase
on_message '/join (.+)' do |username|
# this will be a callback function used later
end
end
class ExtensionBase
def self.inherited(child)
MainAppModule.registered_extensions << child.new
end
def self.on_message(string, &block)
# these need to be set on child instance
#regex = Regexp.new(string)
#on_message_callback = block
end
def exec(message)
args = #regex.match(message).captures
#on_message_callback.call(args)
end
end
# somewhere else in the code, I find the class that I need...
MainAppModule.registered_extensions.each do |child|
puts child.regex.inspect # this is nil and I dont want it to be
if message =~ child.regex
return child.exec(message)
end
end
How can I design this so that the #regex will be set so I can access it within the loop?

Answer 1

I finally found a solution that works, and I have added now the whole code that is executable. Just store the code e.g. in file callexample.rb and call it by ruby callexample.rb
The main difference of my solution to the question is that the call to on_message now creates the instance with the relevant arguments and registers the created instance. Therefore I have deleted the method inherited because I don't need it any more.
I have added some puts statements to demonstrate in which order the code works.
class MainAppModule ## Added class
##registered_extensions = []
def self.registered_extensions; ##registered_extensions; end
end
class ExtensionBase
attr_reader :regex
def self.on_message(string, &block)
MainAppModule.registered_extensions << self.new(string, block)
end
def initialize(string, block)
#regex = Regexp.new(string)
#on_message_callback = block
end
def exec(message)
args = #regex.match(message).captures
#on_message_callback.call(args)
end
end
class MyExtension < ExtensionBase
on_message '/join (.+)' do |username|
# this will be a callback function used later
puts "Callback of #{self} called."
"returnvalue"
end
end
# somewhere else in the code, I find the class that I need...
MainAppModule.registered_extensions.each do |child|
puts "Value of regex: #{child.regex}" # this is no more nil
message = '/join something'
if message =~ child.regex
puts "On match evalue 'child.exec(message)' to: #{child.exec(message)}"
end
end