Helpers

[sethjeffery]

From the README...

Helper methods

You can define helpers with the helper keyword. Helpers can be used within blocks, procs, or as symbolic names for if statements to tidy up your code.

Flagship.define :blog do
  helper :is_author do |comment, user|
    comment.author == user
  end

  def can_view_comment(context)
    context.current_user.moderator?
  end

  enable :comment, if: :can_view_comment
  enable :comment_deletion, if: ->(context) { is_author(context.comment, context.current_user) }
end

To share helpers, you can simply include them as modules.

module FlagHelpers
  def is_author(context)
    context.comment.author == context.current_user
  end
end

Flagship.define :development do
  include FlagHelpers
  enable :delete, if: :is_author
end

Flagship.define :production do
  include FlagHelpers
  enable :delete, if: :is_author
end

[yuya-takeyama]

@sethjeffery
Awesome, I wanted this feature!

But just to confirm, are there any differences between a method defined by helper and one defined by basic def?

[sethjeffery]

Yes the main difference is that helper methods are kept within the instance context of the flagset, but if you define by def it is stored in the Flagship global context shared with all flagsets, which I find a bit dangerous because you can accidentally overwrite definitions.

Modules included with include have been tested to be safe, because it actually uses extend and stores at the instance level.

[yuya-takeyama]

@sethjeffery

if you define by def it is stored in the Flagship global context shared with all flagsets

Oh, that's dangerous...
But I couldn't see such a situation.

require 'flagship'

Flagship.define :a do
  def foo(c)
    puts "foo is called"
    true
  end
end

Flagship.define :b do
  enable :feature, if: ->(c) { foo(c) }
end

Flagship.select_flagset(:b)

p Flagship.enabled?(:feature)

$ bundle exec ruby test.rb
test.rb:11:in `block (2 levels) in <main>': undefined method `foo' for #<Flagship::Dsl:0x007f96e3223090> (NoMethodError)
Did you mean?  fork
        from /Users/yuya/src/github.com/sethjeffery/flagship/lib/flagship/feature.rb:24:in `enabled?'
        from /Users/yuya/src/github.com/sethjeffery/flagship/lib/flagship/flagset.rb:17:in `enabled?'
        from /Users/yuya/src/github.com/sethjeffery/flagship/lib/flagship.rb:20:in `enabled?'
        from test.rb:16:in `<main>'

[sethjeffery]

Hmm you're right! I actually had originally written to use def but I encountered problems so I changed it... now I'm not sure how to reproduce the problems! (Maybe I fixed it through another change?)

[yuya-takeyama]

Maybe by this change?
2817e99

Then I think we don't need helper keyword.
Basically I want to keep the library small.

[sethjeffery]

Ok I'll remove the keyword.

[yuya-takeyama]

LGTM!
Thank you!

[yuya-takeyama]

I'll release this with one more change later today.