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crystal-lang

Crystal: abstract static method

Is it possible to define abstract static methods?

I'm trying:

abstract struct MyStruct
  abstract def self.myfun  # ERR
  abstract def MyStruct::myfun  # ERR
end
Solution

  • Abstract class methods don't appear to be a language feature:

    abstract class Abstract
  abstract self.doit
end
# => Syntax error in /home/bmiller/test.cr:23: unexpected token: self

    However you could always delegate to an instance:

    abstract class Parent
  def self.instance
    @@instance ||= new
  end

  def self.doit
    instance.doit
  end

  abstract def doit
end

class Child < Parent
  def doit
    "ok"
  end
end

p Parent.doit # => can't instantiate abstract class Parent
p Child.doit # => "ok"