allocate.rb

Class.class_eval do
  undef :allocate
end

begin
  p Class.new
rescue => e
  p e
end
# => <Class:0x*******>

Class.class_eval do
  undef :new
end

begin
  p Class.new
rescue => e
  p e
end
# => <NoMethodError: undefined method `new' for Class:Class>

begin
  p Array.new
rescue => e
  p e
end
# => <NoMethodError: undefined method `new' for Array:Class>

begin
  p []
rescue => e
  p e
end
# => []