From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2010-07-31T17:59:51+09:00
Subject: Re: Beginner help needed: use a class def to create new instance

On Sat, Jul 31, 2010 at 2:06 AM, Steve P. <stevepauly@comcast.net> wrote:
> Jesús Gabriel y Galán,
>
> I was able to accomplish (at least crudely) moving code from the main
> body to the class. I felt this was worth doing because I want as much
> logic as possible in the class. (Is this a worthy thing??)
>
> As you advised, I was able to create my new instance using a method that
> returned an object.
>
> Could you please take a look at how I implemented these two methods?
> Account.setupaccount, Account.report
>
> Is this how you would have structured it?
> Any tips or comments greatly appreciated.
> Steve.
>
> #!/usr/bin/ruby
> class Account
>  attr_reader :nbr, :name, :coa
>  def initialize(nbr,name,coa)
>    @nbr=nbr
>    @name=name
>    setcoa(coa)
>  end
>  def setcoa(coa)
>    if ["income", "expense", "asset", "liability",
>     "capital"].include?(coa) then
>      @coa=coa
>    else
>      puts "Error, defaulted to expense"
>      @coa="expense"
>    end
>  end

Maybe call this coa=, as it's a setter?

def coa=(coa)
....
end

>  def Account.setupaccount

def Account.setup_account is more idiomatic. Also I usually do def
self.setup_account, but that's a matter of taste, I guess.

>  #data entry routine inside class, not in main code body.
>    print "enter acct nbr: ";nbr=gets.chomp
>    print "enter name: ";name=gets.chomp
>    print "enter presen: ";coa=gets.chomp
>    return Account.new(nbr,name,coa)
>  end
>  def Account.report(acct)
>  #reporting code inside class, not in main body.
>    puts "===Account Number Listing==="
>    puts "Account Nbr:         #{acct.nbr}"
>    puts "Account Name:        #{acct.name}"
>    puts "Account CofA:        #{acct.coa}"
>  end
> end
> ##Start of main code body ##
> newacct=Account.setupaccount
> Account.report(newacct)
> ##End of Main code body ##

As I said, I don't really like having the user interaction inside the
domain class. For reporting, specially, I would create a to_s method
that formats the account info, and then have the caller of that method
be the one writing to stdout or to a file or whatever:

def to_s
s=<<EOF
===Account Number Listing===
Account Nbr:         #{acct.nbr}
Account Name:        #{acct.name}
Account CofA:        #{acct.coa}
EOF
s
end

> When I clear my confusion about this, I will do something like
> class Ledger < Account
>  ##code to make an array of the Account objects and add more
> functionality
> end

If you want an array of Account objects, you shouldn't inherit from
Account, but rather have an instance variable that holds an array of
Accounts:

class Ledger

  def initialize
    @accounts = []
  end
  ...
end

Jesus.