Undefined method when calling method from initialize in ruby
ruby
Solution
In ruby `super` means calls superclass implementation of the current method - it is not, unlike some languages a mechanism for calling arbitrary methods from the base class.
super.writeFoo
Calls the superclass implantation of the current method (ie `writeFoo`) and then calls writeFoo on the result of that (hence the error).
Problem
I have a class that inherits from another. When calling the constructor in the child it is making a call to the parent, which makes a call to a method. For me that should work perfectly fine but I get an exception. The ruby code looks like: ``` class MyTestClass def initialize @foo = "hello world" puts "init parent" writeFoo end def writeFoo puts @foo + " from base" end end class MySubClass < MyTestClass def initialize puts "init sub" super end def writeFoo puts @foo + " from sub" super.writeFoo end end @foo = MySubClass.new ``` When running that code I get an undefined method exception as below, but the right output is printed. Can someone please explain why? ``` /Users/tj/dev/coursera/sml/hw6/test.rb:21:in `writeFoo': undefined method `writeFoo' for nil:NilClass (NoMethodError) from /Users/tj/dev/coursera/sml/hw6/test.rb:5:in `initialize' from /Users/tj/dev/coursera/sml/hw6/test.rb:16:in `initialize' from /Users/tj/dev/coursera/sml/hw6/test.rb:25:in `new' from /Users/tj/dev/coursera/sml/hw6/test.rb:25:in `<main>' init sub init parent hello world from sub hello world from base [Finished in 0.1s with exit code 1] ```