From: Bill Guindon <agorilla@...>
Date: 2005-10-23T07:35:51+09:00
Subject: Re: A comparison by example of keyword argument styles

On 10/21/05, Berger, Daniel <Daniel.Berger@qwest.com> wrote:
> > -----Original Message-----
> > From: Trans [mailto:transfire@gmail.com]
> > Sent: Friday, October 21, 2005 8:12 AM
> > To: ruby-talk ML
> > Subject: Re: A comparison by example of keyword argument styles

<snip>

> > If keywords integrate the interface too tightly
> > with the code, then why tie them to the interface? Also, I
> > imagine there many be many more keyword arguments then
> > ordered args, this will make for some very LONG constructors:
> >
> >   def stadium( height:, seating_capacity:, location:, color:,
> > sports:, concessions:, extra_features:, indoor:, yadayadayada: )

<snip>

> I'm glad you brought this example up.  What do you do when you have a
> ton of accessors in your class?  I have just such a case with the Format
> class in the spreadsheet package, where you have "font_name",
> "font_size", "border_color", etc.  About 30 accessors I think.
>
> The solution here is NOT keywords arguments (regardless of
> implementation), where you would end up with ridiculously long
> constructors, as you mentioned.  It's the old "yield self if
> block_given?" trick:
>
> class Format
>    attr_accessor :font_color, :font_size, :bold # ...
>    def initialize
>       yield self if block_given?
>    end
> end
>
> format = Format.new do |f|
>    f.font_color = "blue"
>    f.font_size  = 10
>    f.bold       = true
>    ...
> end

Has any thought been given to defining the parameters and keywords
using something similar to attr_accessor?  Seems that would reduce the
long constructor problem, and would be fairly developer friendly.

It's always seemed strange to me that the two formats differ, seems a
nuisance when you've built up either the attr_accessor list, or your
parameter list, and you have to hand massage one to the other.

class Format
  attr_accessor :font_face, :font_color, :font_size, :bold, :italic
  def initialize
    parameters :font_face='arial'
    keywords :font_color='black', :font_size, :bold=false, :italic=false
    ...
  end
end

format = Format.new('verdana')
format = Format.new(font_size: 1, bold: true)
format = Format.new('verdana', italic: true, font_size: 10)

granted, functon calls and constructors could still get quite lengthy.

disclaimer: this is not a thought that I'm in love with, just one that
crossed my mind.

> Regards,
>
> Dan

[OT] many thanks to those who put together the conference, and the videos.

--
Bill Guindon (aka aGorilla)