Add a variable to a class instance at runtime
Add a variable to a class instance at runtime
You are encouraged to solve this task according to the task description, using any language you may know.
You are encouraged to solve this task according to the task description, using any language you may know.
This demonstrates how to dynamically add variables to a class instance at runtime. This is useful when the methods/variables are based on a data file that isn't available until runtime. Hal Fulton gives an example of creating an OO CSV parser at An Exercise in Metaprogramming with Ruby
Python
class empty(object):
pass
e = empty() setattr(e, "foo", 1) print e.foo
Ruby
class Empty end e = Empty.new e.instance_variable_set("@foo", 1) e.instance_eval("class << self; attr_accessor :foo; end") puts e.foo