Feature #16817: attr_predicate or attr_query or attr_something for ? methods

• Status: Open
• Assignee: -
• Target version: -

[robotdana (Dana Sherson)]

I would like attr_predicate like attr_reader etc.

attr_predicate :cat would define a method named :cat? that returned the value for ivar @cat.

I would like this because i find myself writing this:

def cat?
  @cat
end

which is fine once, but becomes tedious with many attributes

Another possibility is allowing attr_reader :cat? to define a method that returns the value for ivar @cat. currently it raises NameError (invalid attribute name cat?')`

Thank you

[sambostock (Sam Bostock)]

attr_predicate :cat would define a method named :cat? that returned the value for ivar @cat.

I think it would make sense for the predicate method to convert the value to true or false before returning it, to make a clear distinction between a regular "getter" method, and a "predicate" method.

def cat?
  !!@cat
end

[hsbt (Hiroshi SHIBATA)]

• Project changed from 14 to Ruby

[nobu (Nobuyoshi Nakada)]

• Related to Feature #21555: Add support for predicate attribute reader names added