ruby - Predicate method syntax -

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i made class these methods:

def promotion_available?   promotion.present? end  def promotion   @promotion ||= promotionuser.user(@user.id).available.first end

then, colleague removed promotion method, , changed predicate promotion_available? in way:

def promotion_available?   @promotion ||= promotionuser.user(@user.id).available.first end
  • can set instance variable directly on predicate method?
  • can predicate method return entire object instead of true/false (i think no, colleague says opposite)?

can set instance variable directly on predicate method?

yes, there's nothing wrong it. often.

can predicate method return entire object instead of tre/false (i think no, colleague says opposite)

yes, common. works if use idiomatic ruby truthiness checks.

if obj.promotion_available? # if obj.promotion_available? == true # bad!

remember, nil , false in ruby falsey values. else true. why returning object or nil works kinda returning true or false.


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