From: Akinori MUSHA <knu@...>
Date: 2000-10-05T06:16:52+09:00
Subject: [ruby-talk:5292] RFC: Enumerable#every(n)

Hi,

Let me show you a new method candidate for Enumerable module, which I
named "every".  (I might not have implemented it this cleanly without
yashi and znz's help.  Thanks much!)

		*		*		*

Enumerable#every(n)

    Returns an Enumerable object that yields the iterator block for
    every <n> elements.  The block is yielded with <n> arguments for
    each, and if the number of elements are short by <n> for the last
    yield, nil's are filled as necessary.

Example 1:
    Enumerate the alphabets for every quartet and select ones that
    don't start with vowels:

$ ruby -e 'p (("A".."Z").every(4).find_all{|i| "AEIOU".index(i[0]) == nil})'
[["M", "N", "O", "P"], ["Q", "R", "S", "T"], ["Y", "Z", nil, nil]]

Example 2:
    List the files in the current directory in 3-column format:

$ ruby -e 'Dir.open(".").every(3).each{|i| puts "%-20s%-20s%-20s" % i}'
.                   ..                  CVS                 
cygwin              djgpp               ext                 
lib                 misc                missing             
sample              win32               x68                 
README.EXT.jp       .cvsignore          COPYING             
ChangeLog           MANIFEST            Makefile            
Makefile.in         README              README.EXT          
(snip)
string.o            struct.o            time.o              
util.o              variable.o          version.o           
dmyext.o            libruby.a           main.o              
miniruby            rbconfig.rb         libruby.so.16       
libruby.so          ruby                                    


The implementation is available at the following URI:

	http://people.FreeBSD.org/~knu/misc/rb_enum_every.diff


Now I'd ask you some questions:

1) Is the name "every" appropriate?

2) Is it worth being integrated to the standard Enumerable class?


Any comments are welcome.  Thanks in advance.

-- 
                           /
                          /__  __       
                         / )  )  ) )  /
Akinori -Aki- MUSHA aka / (_ /  ( (__(  @ idaemons.org / FreeBSD.org

"We're only at home when we're on the run, on the wing, on the fly"