A super-easy and great way to implement Gem configuration

Rails
1

Just did this in my constance gem, and totally love it as a way to add
configuration or options configurability to your gem:
http://stufftohelpyouout.blogspot.com/2012/09/forget-struct-and-openstruct-flexible.html

like:

module MyModule
class << self
attr_accessor :debug, :proc, :some_mapping
def configure(&block); yield; end
end
end

I’ve seen people that use OpenStruct, Struct, and I had my own way to do
it
before this, but this seems a lot better.

2

I am not sure that this way is simple. I usually use for gem
configuration
this code

require ‘active_support/configurable’
module GemModule
include ActiveSupport::Configurable

class << self
def setup
yield config
end
end
end

And then you can write

GemModule.setup do |config|
config.option1 = “value1”
config.option2 = 2
end

And

GemModule.config.option1

=> “value1”

Moreover, you can define method_missing in you module and delegate
unknown
methods to self.config. Then you will be able to write
GemModule.option1

=> “value1”

, 22 2012 ., 18:38:22 UTC+3 gsw :

3

On Sunday, September 23, 2012 8:11:43 AM UTC-4, Ilia B. wrote:

  yield config

ActiveSupport::Configurable

That works, but it has the following disadvantages over the method I
described:

  1. If you use ActiveSupport::Configurable you are tied to using
    activesupport/Rails. Many times you want to write the Gem so that it
    isn’t
    Rails-specific and want to limit dependencies.
  2. I know Rails uses the “pass the config into the block thing”, but it
    isn’t as DRY as not typing “config.” before each parameter.
  3. By defining the attr_accessors, you limit the chance that a user will
    mistype/misspell a variable.
  4. The way you described allows the user to define config parameters
    with
    procs and lambdas, but the way I describe allows the user to define
    “config
    parameters” as procs, lambdas, and methods, i.e. the user can actually
    just
    define a variable as:

def some_variable_name

some really involved implementation here, even refactored into

various
methods, etc. in the block.
end

See more at:
http://stufftohelpyouout.blogspot.com/2012/09/forget-struct-and-openstruct-flexible.html

Hope that helps.

4

Just as an update, I had bugs in the previous code provided and fixed
with
help from Jess Gabriel y Galn and Calvin B. on the list in this post:
http://www.ruby-forum.com/topic/4406183

module MyModule
class << self
attr_accessor :debug, :proc_or_lambda, :some_array, :some_hash,
:time
def configure(&blk); class_eval(&blk); end
end
end

and can configure like:

MyModule.debug = true

MyModule.proc_or_lambda = lambda{|a,b| puts “a=#{a} b=#{b}”}

…

or

MyModule.configure do
@debug = true
@proc_or_lambda = lambda{|a,b| puts “a=#{a} b=#{b}”}
@some_array = [:foo,:bar]
@some_mapping = {:key => ‘value’}
def self.time; Time.now; end
end

or

MyModule.configure do
self.debug = true
self.proc_or_lambda = lambda{|a,b| puts “a=#{a} b=#{b}”}
self.some_array = [:foo,:bar]
self.some_mapping = {:key => ‘value’}
def self.time; Time.now; end
end

Posted here with more examples:
http://stufftohelpyouout.blogspot.com/2012/09/forget-struct-and-openstruct-flexible.html