I need to add a bit of business logic to my Commerce site: a boolean field on product nodes marks that the corresponding products can't be delivered outside the UK.
And I know the way to do this in Commerce is to create a rule: react to the cart completing checkout, iterate over line items, check the corresponding products, and block the completion if the field in question is set.
Rules is great: with Rules, site builders can change site functionality and cause it to react to events. When non-techy people ask if my job involves designing websites, to put them right I say, 'I make websites go "bing!"'; and now, site builders can make them go 'bing!' too.
But I have a confession: I'm reluctant about using Rules. It's partly that I find the UI confusing, and it feels time-consuming to test them, but deeper than that I think it's just that I feel too far removed from the actual thing I'm trying to make.
And that makes me wonder: am I becoming a Drupal dinosaur?
Because I can imagine when Views first came along, developers who were used to writing their own query and formatting the result themselves, looking at the Views UI and thinking 'I don't feel in control of my lists of stuff any more'.
Or before CCK, developers wrote exactly the form elements they needed in the node form and saved it themselves in the database. I still sometimes speak to non-Drupal developers who want to be able to dump data into the node table directly (or pull it out) and when I tell them they can't, because the data that actually makes a node is spread out over the node table, the node_revision table, and then a multitude of field tables. And their feeling of disconnection at not being able to get their hands on 'the node' as a solid lump of database stuff must surely be akin to what I feel with Rules. And I'm going to call this feeling 'abstraction shock'.
I want to write a hook. I want to write the code for it, for it to feel like a solid thing. I know that my rule can (indeed, should) be exported to code, but I want code that I can read and see exactly what it says, rather than code that Rules will consume and understand. And most of all, I want to be able to put in debug statements to understand what I'm getting as I write it, and after I've written it when it's going wrong or when the site functionality has to change.
If that makes me a dinosaur, save me a seat next to the brontosaurus.