This is probably going to be a terrible idea, but if Basket.line_items
isn't safe, then maybe what's needed is a method on the model that
returns a list of line_items that is safe.
|class Basket #or maybe Class ActiveRecord if you want it everywhere.
def safe_line_items
line_items || []
end
end
#and
||<% @basket.safe_line_items.each do |item| %>
<p><%= item %></p>
<% end %>|
1) Excuse any syntax errors as I've been away from Ruby for a while.
2) If this is a terrible idea, please tell me why this is a terrible idea.
Peter Morris wrote:
This discussion started when the need for a 'guard if' was removed
because we ensured that the object we return behaves the same in all
experienced cases. Injecting new differences to the interface would
seem to be moving away from that ideal.
On 23 February 2016 at 19:45, Peter Morris <[email protected]
<mailto:[email protected]>> wrote:
When I say 'breaks ducks' I mean it breaks the implicit interface
contract.
I expect it to quack when I expect, not bark.
On 23 February 2016 at 15:49, Graham Ashton <[email protected]
<mailto:[email protected]>> wrote:
On Tue, 23 Feb 2016, at 03:31 PM, Peter Morris wrote:
> but having #save raise an exception breaks ducks. save
doesn't raise exceptions.
If it would be an error to call `#save` on a missing basket,
your code won’t do it, so there’s no problem. If you make a
mistake and your code does do it, you want to know about it,
so you really want it to raise.
Can you elaborate on what “breaks ducks” means? I’m finding it
hard to describe what I think you’re trying to say. As in,
what’s the actual problem?
Are you saying that any object that quacks like a Duck must
have the same API as Duck, even if you never call some of
those methods on the duck-like object?
Here’s another way to think about it…
If I wrote `Basket` and `MissingBasket` from scratch (without
inheritance, or ActiveRecord), and needed to call `#save` on
both of them, I’d implement it on both of them (reusing code
as/if appropriate).
If I only ever needed to call it on `Basket` I wouldn’t define
it on `MissingBasket` as well, just because `Basket` needed a
`#save` method.
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