A lot of the built-in Rails classes have configuration options that
can be set in environment.rb, but there doesn't seem to be any
standard way of doing the same thing for your own classes. The
following are my initial thoughts on solving this, some simple code,
and a few related questions.
Let's say I have a model called MyModel. In MyModel, I'd like to be
able to do something like this:
class MyModel
include Configurable
config_attr :example_attribute, "Here's a default value"
def my_method
p config.example_attribute
end
end
Then, in environment.rb:
MyModel.configure do
self.example_attribute = "Here's the configured value"
end
There's code at the end of the e-mail to implement a simple version
of this.
The questions:
1) How do I work around reloadable classes?
The old Rails approach to adding configuration was:
class MyModel
@@example_attribute = "Here's a default value"
cattr_accessor :example_attribute
end
and in environment.rb:
MyModel.example_attribute = "Here's the configured value"
This dies for model classes because MyModel is trashed and reloaded
on each request, overwriting the value set in environment.rb with the
default one after the first request. My code below suffers from the
same problem.
Anyone got any ideas on neat ways to work around this? I can think of
a couple of approaches, but they're all really ugly.
2) Would something along these lines be a possibility for inclusion
in a future version of Rails? I know it's far from being rocket
science, but with the proliferation of plugins, engines, etc. it
would be nice to have a standard way that this is done, if only so
that you know where to look for configuration when using third-party
code.
3) What do people think of the API approach I've suggested? I'm
trying to make it as simple as possible, not force you to manually
define a separate class or module just to hold configuration, but
still do strict config checking in environment.rb.
Cheers,
Pete Yandell
module Configurable
def self.included(base)
base.class_eval do
@@config = Class.new unless defined?(@@config)
cattr_reader :config
end
base.extend(ClassMethods)
end
module ClassMethods
def config_attr(name, value)
config.cattr_accessor name
config.send("#{name.to_s}=".to_sym, value)
end
def configure(&block)
block.bind(config).call
end
end
end
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