Ruby 2.7+.
I have methods in a couple of modules that are mixed in, and are invoked with super. Each of the module methods invokes super in turn, so all methods by that name in the mixed-in modules are invoked, although perhaps not in a deterministic order.
My question is: Can a method tell programmatically (as opposed to hard-coding) from what module it's been mixed in?
module A
def initialize(*args, **kwargs)
puts("something magic")
end
end
module B
def initialize(*args, **kwargs)
puts("something magic")
end
end
class C
include A
include B
def initialize(*args, **kwargs)
puts("actual #{class.name} initialize")
super
end
end
When run, this will print three lines. What I'm seeking is something like class.name, specific to each module, that identifies the module that supplied the initialize method that's running. The "something magic* strings would be replaced with this actual magic. 🙂
Thanks!
My first attempt was to call super_method to get all the initializers up the stack:
module A
def initialize
A # return for comparison
end
end
module B
def initialize
B
end
end
class C
include A
include B
def initialize
C
end
def super_initializers
init = method(:initialize)
while init
print init.call, " == " # get hardcoded module from `initialize`
p init.owner # get the module dynamically
init = init.super_method # keep getting the super method
end
end
end
>> C.new.super_initializers
C == C
B == B
A == A
== BasicObject
Second idea is to use Module.nesting, I think this is what you're looking for:
module A
def initialize
# i, o, m = method(:initialize), [], Module.nesting[0]
# while i; o << i.owner; i = i.super_method; end
# print "prev "; p o[o.index(m)-1] # previous super
puts "A == #{Module.nesting[0]}"
# print "next "; p o[o.index(m)+1] # next super
super
end
end
module B
def initialize
puts "B == #{Module.nesting[0]}"
super
end
end
# add a class
class Y
def initialize
puts "Y == #{Module.nesting[0]}"
super
end
end
# add some nesting
module X
class Z < Y
def initialize
puts "Z == #{Module.nesting[0]}"
super
end
end
end
class C < X::Z
include A
include B
def initialize
puts "C == #{Module.nesting[0]}"
super
end
end
>> C.new
C == C
B == B
A == A
Z == X::Z
Y == Y
Actually, never thought about that this could be useful, but it works:
def super_trace m
while m;
p m.owner; m = m.super_method
end
end
>> super_trace User.new.method(:save)
ActiveRecord::Suppressor
ActiveRecord::Transactions
ActiveRecord::Validations
ActiveRecord::Persistence