Improve the documentation of the format and of interpolations

[oliverklee]

I'm using this in my HAML page layout:

%title= page_title format: ':default | :app'

If I understand the docs correctly, this should result in the translated app.tagline, a pipe, and the app.name. However, :default is output unreplaced. Am I understanding the docs incorrectly, or is this a bug?

(:app.tagline does not work either - in that case, only :app gets substituted with the translated app.name.)

[lwe]

I guess this is more a case of bad documentation or confusing documentation. :default is not an extrapolation (to use in the format string), but a option:

page_title format: ':title | :app :env', default: :'app.tagline', app: 'MyApp'

# The format string is then passed through the extrapolations and
#
# :title -> gets replaced by the title, or if there is no tagline by the option `default`
# :app -> gets replaced by the app.name or in our case by the option `app`
# :env -> if a custom registration was registered it would be replaced... like:

PageTitleHelper.interpolates :env do |env|
  "[#{Rails.env}]" unless Rails.env.production?
end

does this clarify the usage of default, but reading the docs just now I had to double check it too :)

[oliverklee]

Okay, then the documentation indeed needs some improvements. :-) I've updated the ticket title accordingly.

[oliverklee]

Note to self: These are the interpolations I have been able to find so far:

:title -> namespace.controller.action.title
:app -> app.name

[lwe]

Check out Interpolations module here: https://github.com/lwe/page_title_helper/blob/master/lib/page_title_helper.rb#L15-L33

title and app are the only defined methods and thus the only known interpolations out of the box currently.