From: "Peña, Botp" <botp@...>
Date: 2003-07-09T17:56:38+09:00
Subject: Re: Array.each

Brian Candler [mailto:B.Candler@pobox.com] wrote:
> > 
> > a=(1..10)
> > a.each {| x , y|  p x }
> > 
> > 1
> > 3
> > 5
> > 7
> > 9
> 
> A more general pattern might be:
> 
> module Enumerable
>   def each_group(n=1)
>     res = []
>     each do |i|
>       res << i
>       if res.size >= n
>         yield res
>         res = []
>       end
>     end
>     yield res if res.size > 0
>   end
> end
> 
> By making it part of 'Enumerable' and only depending on 
> 'each', it works for any enumerable class:
> 
> (1..10).each_group(2) { |x,y| puts x }  # prints 1,3,5,7,9

cool, but why not use #arity for block's param count, no? I would then use
the param for the default like...

C:\family\ruby>type a1.rb

#class Array
module Enumerable
  def each_group(defval=nil,&block)
    n = block.arity
    res = []
    each do |i|
      res << i
      if res.size >= n
        yield res
        res = []
      end
    end
    if res.size > 0
       res << defval until res.size >= n
       yield res
    end
  end
end

# what follows are just testing
x = '(1..8).to_a.each_group {|x,y,z| p "x = #{x};  y = #{y.inspect};   z =
#{z.inspect}"}'
p "running #{x} using default = nil"
eval x
p '-----------'

x = '(1..7).to_a.each_group(9999) {|x, y,z| p "x = #{x};  y = #{y.inspect} ;
z= #{z.inspect}"}'
p "running #{x} using default = 9999"
eval x

p '-----------'
x = '(1..5).to_a.each_group([1,2]) {|x, y,z| p "x = #{x};  y = #{y.inspect}
;  z = #{z.inspect}"}'
p "running #{x} using default an array [1,2]"
eval x
p '-----------'
x = '(1..2).to_a.each_group({"test"=>1}) {|x, y,z| p "x = #{x};  y =
#{y.inspect} ;  z = #{z.inspect}"}'
p 'running #{x} using default a hash {"test"=>1}'
eval x
p '-----------'
x = '(1..1).to_a.each_group("hehehe") {|x, y,z| p "x = #{x};  y =
#{y.inspect} ;  z = #{z.inspect}"}'
p "running #{x} using default a string 'hehehe' "
eval x

#and outputs...
C:\family\ruby>ruby a1.rb
"running (1..8).to_a.each_group {|x,y,z| p \"x = #{x};  y = #{y.inspect};
z =#{z.inspect}\"} using default = nil"
"x = 1;  y = 2;   z = 3"
"x = 4;  y = 5;   z = 6"
"x = 7;  y = 8;   z = nil"
"-----------"
"running (1..7).to_a.each_group(9999) {|x, y,z| p \"x = #{x};  y =
#{y.inspect};  z = #{z.inspect}\"} using default = 9999"
"x = 1;  y = 2 ;  z = 3"
"x = 4;  y = 5 ;  z = 6"
"x = 7;  y = 9999 ;  z = 9999"
"-----------"
"running (1..5).to_a.each_group([1,2]) {|x, y,z| p \"x = #{x};  y =
#{y.inspect} ;  z = #{z.inspect}\"} using default an array [1,2]"
"x = 1;  y = 2 ;  z = 3"
"x = 4;  y = 5 ;  z = [1, 2]"
"-----------"
"running #{x} using default a hash {\"test\"=>1}"
"x = 1;  y = 2 ;  z = {\"test\"=>1}"
"-----------"
"running (1..1).to_a.each_group(\"hehehe\") {|x, y,z| p \"x = #{x};  y =
#{y.inspect} ;  z = #{z.inspect}\"} using default a string 'hehehe' "
"x = 1;  y = \"hehehe\" ;  z = \"hehehe\""

> Regards,
> 
> Brian.


kind regards -botp