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Uwe Schmitt

12/8/2005 4:24:00 PM



Hi,

I'm trying to write a parser for cooking recipes.
It looks like this:

-----
require 'bspmess'
class Parser

STATES = [ :FIND_START, :SCAN_HEADER]

methods = { :FIND_START => self.find_start,
:SCAN_HEADER => self.scan_header
}

def initialize(msg)
@msg = msg
@state = :FIND_START
end

def run
@msg.each { |line|
scan line
}
end

def scan(line)
methods[@state].call(line)
end

def find_start(line)
puts "find_start "
@state = :SCAN_HEADER
end

def scan_header(line)
puts "scan header"
end


end


p = Parser.new(MSG)
p.run

-----

I get an error when the scan method is called first:
undefined method `find_start' for Parser:Class (NoMethodError)

Who can help me ?

Thanks in advance,

Uwe
1 Answer

Edward Faulkner

12/8/2005 5:00:00 PM

0

On Fri, Dec 09, 2005 at 01:32:35AM +0900, Uwe Schmitt wrote:

> methods = { :FIND_START => self.find_start,
> :SCAN_HEADER => self.scan_header
> }

This doesn't do what you want. It's trying to call the "find_start"
and "scan_header" methods on the Parser Class object. There are
several possibilities to do this correctly:

1. Call self.instance_method(:find_start) to get an unbound method,
which you'll need to #bind before calling it.

2. Construct your "methods" table in #initialize, and use
self.method(:find_start) to get a bound method.

3. Don't build a method table at all. Do this instead:

def scan(line)
self.send(@state,line)
end

regards,
Ed