From: Steve Tuckner <STUCKNER@...>
Date: 2002-11-09T01:09:54+09:00
Subject: Re: Beginner Question (Idiomatic way to subset an array

I didn't think about the fact that this would generate an a ProcessInfo
object but an Array object. It seems that that kind of negates some of the
usefulness of select (and possibly other enumerable functions such as
reject) when you are sub-classing Array.

Why isn't the implementation of select like below?

module Enum
	def select2()
		a = self.class.new
		each do |x|
			if yield(x) then
				a.push(x)
			end
		end
		a
	end
end

class Array
	include Enum
end

class A < Array
end

a = A.new
a.push(1)
a.push(2)
b = a.select2{|x| x == 1}
p b					==> [1]
print b.class, "\n"           ==> A

I guess it could be that then it would require any class that includes array
to have a constructor that accepts no arguments. Is that too big of a
limitation? Are there other ways around this problem?

Steve Tuckner

-----Original Message-----
From: Steve Tuckner [mailto:STUCKNER@MULTITECH.COM]
Sent: Friday, November 08, 2002 9:03 AM
To: ruby-talk ML
Subject: Re: Beginner Question (Idiomatic way to subset an array


processInfo.select{|x| process['realm'] == realm}

-----Original Message-----
From: Booth, Peter [mailto:Peter.Booth@gs.com]
Sent: Friday, November 08, 2002 8:51 AM
To: ruby-talk ML
Subject: Beginner Question (Idiomatic way to subset an array


I'm wondering if there is a more idiomatic way to do the following?
Can Array.collect be used to extract a subset of an array?

Peter

Can

class ProcessInfo < Array

	def findByRealm(realm)
		result = ProcessInfo.new
		each { |process|
			if process['realm'] == realm
		  		result << process
		  	end
		 }
		 return result
	end

end