Derived-class initialization

Ruby
1

Hello all,

I’m having some trouble with extending an existing Ruby class in order
to add functionality. Here’s some example code:

class Graph
…
…
def subgraph(*args)
graph = self.new
…
…
return graph
end
end

class AwesomeGraph < Graph
…
…
def do_something
…
…
end
end

g = AwesomeGraph.new
a = g.subgraph(g.nodes)
a.do_something // ERROR! No Graph#do_something exists!

I was hoping ‘self.new’ would take into account the derived class used
upon creation, but it doesn’t.

Any suggestions?

–
Thanks!
Bryan

2

2009/3/18 Bryan R. [email protected]

…
…
return graph
end
end

This looks suspect, ‘self’ in this method looks like it will refer to
the
Graph instance, not the Graph class. Try self.class.new instead.

3

Yep… that worked. :slight_smile:

–
Thanks!
Bryan

James C. wrote:

2009/3/18 Bryan R. [email protected]

…
…
return graph
end
end

This looks suspect, ‘self’ in this method looks like it will refer to
the
Graph instance, not the Graph class. Try self.class.new instead.