Set config through a config block instead of direct assignment

[kevinnio]

Hi there. Some colleagues and I were working with wicked_pdf and wkhtmltopdf-heroku when we noticed an issue. The latter gem adds a new value to WickedPdf.config[:exe_path] but the app was not getting it. Turns out our initializer overwrites the whole hash by doing WickedPdf.config = { ... }. I noticed the README says this is the recommended way to set config.

Of course the fix is simple enough but I wonder if something similar has happened to other devs. IMHO, there's a better way to set config by using a config block pattern:

# inside config/initializers/wicked_pdf.rb
WickedPdf.configure do |config|
  config[:page_size] = "Letter"
end

# inside any other gem:
WickedPdf.configure do |config|
  config[:exe_path] = CUSTOM_EXE_PATH
end

This way config is never completely overwritten, only specific keys, and values from other gems can be preserved and combined. We can also have default values if we need them.

What do you all think about this? I could implement this myself if you all feel this would be useful. We can still support WickedPdf.config = and even add a deprecation warning for it.

[unixmonkey]

This sounds like a good idea. I remember looking into it years ago, but it was never a priority. I would like to maintain backwards compatibility though.

[kevinnio]

First draft of my MR has been submitted.