From: William James <w_a_x_man@...>
Date: 2005-09-14T09:36:33+09:00
Subject: Re: Adventures in html decoding.

mathew wrote:
> William James wrote:
> > ARGF is no more esoteric than ARGV, [...]
>
> I disagree. ARGV is familiar to anyone who's ever written C, C++,
> Objective-C, Java, Perl, AWK, Python, Scheme, ...
> ARGF is not.

These are not familiar to everyone who's ever written in C or Awk:

  class, map, join, __END__, DATA, <<HERE, grep, flatten

But that doesn't prove they are esoteric to those who use Ruby.

>  I'd never heard of it until this thread.

Major premise:
I know everything about Ruby except that which is esoteric.

Minor premise:
I don't know about ARGF.

Conclusion:
ARGF is esoteric.

>
> Compare the number of references to ARGV and ARGF in the pickaxe book
> too: ARGF is only mentioned three times in the entire book according to
> the index.


Pickaxe (1st edition), page 16:

  The "Ruby way" to write this would be to use an iterator:

    ARGF.each { |line| print line if line =~ /Ruby/ }

on page 219 under the heading "Standard Objects" these are listed:
  ARGF, ARGV, ENV, false, nil, self, true

page 217 explains ARGF's synonym, $<.


"Teach Yourself Ruby in 21 Days" explains ARGF in Day 8 on
page 173 and uses it in the final two solutions to a problem.
The penultimate one is

  has_a_long_word = /\w{5,}/
  ARGF.each{|line| print line unless has_a_long_word =~ line}

Matz himself in "Ruby in a Nutshell" explains it on page 38
and lists it as one of 14 predefined global constants.


> One of those is in a grey "you can skip this" section talking
> about Perlisms,

For that the authors should be afflicted with the Spell of
Forlorn Encystment.


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Usage tip:  the name of the file currently being read is available as
$FILENAME or as shown in this example:

ruby -e 'ARGF.each{|x| print ARGF.filename + ", " + x }' file1 file2