Inclusion & exclusion predicates

[fran-worley]

The current inclusion and exclusion predicates take a list and check that the input is included in that list.

I have just run into a use case where I want to turn this on its head and instead check that the input includes a value.

#current predicate:
predicate(:inclusion?) do |list, input|
  list.include?(input)
end

#what I need...
predicate(:some_new_predicate?) do |value, input|
  input.include?(value)
end

Does this seem like something worth adding to the library?

In terms of names I guess we either go for :includes? and :excludes? the idea being that we are checking if an input includes or excludes something. However they might be a little similar to the current predicates...

[solnic]

Yes it is, you're not the first person who asked for it. IIRC we thought about naming it contains? but I'd be ok with includes? and excludes? although there's a risk people will be confused with inclusion? vs includes? - but I gotta say I never ever liked inclusion?, we picked it up because people are familiar with it. Blah

[fran-worley]

I thought of contains but what do you do for the opposite? I wasn't happy with anything I came up with (does_not_contain, missing, absent, lacks).

You could do:

input.includes?(value) 
input.included_in?(list) #instead of inclusion

input.excludes?(value)
input.excluded_from?(list) #instead of exclusion

We could always create aliases for inclusion and exclusion for backwards compatibility.

[fran-worley]

Or (might be a bit much magic) you could determine what to call .include? on based on the type of argument supplied similar to how the Size predicate works.

Actually, that isn't a good idea please ignore!!

[timriley]

I like your suggestion, @fran-worley:

input.includes?(value) 
input.included_in?(list) #instead of inclusion

input.excludes?(value)
input.excluded_from?(list) #instead of exclusion

It looks a lot clearer to me, and it seems @solnic isn't attached to the current naming. Now might also be a good time to get it in, given we're changing the basic DSL anyway.

Would you be up for making this change (and deprecating the other names) along with https://github.com/dry-rb/dry-logic/pull/9?

[fran-worley]

Yup will do. I'll also PR dry-v and the docs to update .

[fran-worley]

closed via #9