From: Johnny Morrice <spoon@...>
Date: 2011-05-28T05:09:17+09:00
Subject: Re: Hash .each and different action for each key

On Sat, 28 May 2011 04:44:20 +0900
Igor Nn <storm8000@gmail.com> wrote:

> Hello -
> I have a hash table of several items.
> 
> What I would like to do is loop through the hash and do a different
> action based on each unique key.

> my_hash_table.each_pair do |k, v|
>   # Call a method if a hash key == "a"
>   # Call a different method if hash key == "b"
>   # Call a third method if a hash key == "c"
> end

What you ask for is this:

funcs = {}
funcs["a"] == lambda {|v| puts "method for key 'a' with value: #{v}"}

my_hash_table = {}
my_hash_table["a"] = "Hmmmmm!"

my_hash_table.each_pair do |k, v|
   funcs[k].call v
end

Are you sure you want that?  It smells way bad.  It's incoherent.

Is there any thing wrong with the hash values being objects which do
what you want, in each case.

E.g.

class Car
   def drive
      puts "broom, broom!"
   end
end

class Moped
   def drive
      puts "nnnnnnnnn!"
   end
end

vehicles = {}
vehicles["a"] = Car.new
vehicles["b"] = Moped.new

vehicles.each_value do |veh|
   veh.drive
end

Much more coherant.  Abstracts detail of algorithm from loop body into
objects in well defined manner.  Can be extended to do different things.

Cheers
Johnny