Errata for Everyday Scripting with Ruby

#26880: In the first paragraph of section 2.2, second sentence, you have, "The comand-line interpreter is a program that lets you command the compiler ...". The word "compiler" should be "computer".--Kim Shrier

#30750: Following the code example, the following sentence appears: "The new message is defined at #1." Doesn't this code example define a "method," not a message? If it does in fact define a message, then the references to method on the rest of this page should be changed to match. (I think; correct me if I'm wrong.)--Michael Yacavone

#47038: At the end of the last sentence of the explanation accompanying the fourth example from the bottom of the page "…message arguments are always in parentheses.)" is not true. "a.delete_at 0" works just fine.--Bruce Hobbs

#50401: svn: Network connection closed unexpectedly

tl;dr - root = "ht tp://churn-demo.rubyforge.org/svn"
(delete the space between ht and tp)

when running:

prompt> svn log --revision 'HEAD:{2005-07-30}' svn://rubyforge.org/var/svn/churn-demo/inventory

or even just running the command: svn log svn://rubyforge.org/var/svn/churn-demo

So running churn.rb would result in:

salman@saleheen:~/everyday_scripting/churn$ ruby churn.rb
Changes between 2005-07-07 and 2005-08-04:
svn: Network connection closed unexpectedly
svn: Network connection closed unexpectedly
svn: Network connection closed unexpectedly
svn: Network connection closed unexpectedly
svn: Network connection closed unexpectedly
svn: Network connection closed unexpectedly
util (-1 changes) *
ui (-1 changes) *
persistence (-1 changes) *
inventory (-1 changes) *
fulfillment (-1 changes) *
audit (-1 changes) *

According to the rubyforge FAQ:

Anonymous cvs/svn checkouts and exports keep failing

Sometimes you'll see a svn: Connection closed unexpectedly error message when you try to export or check out a Subversion repository using anonymous Subversion - e.g., svn co svn://rubyforge.org/var/svn/rspec/trunk/rspec rspec. Or with CVS, the message will be something like cvs [checkout aborted]: end of file from server (consult above messages if any). This is probably happening because we throttle anonymous connections based on server load (using xinetd). You may instead want to use HTTP for anonymous Subversion checkouts instead -e.g., svn co ht tp://rspec.rubyforge.org/svn/trunk/rspec rspec.

(ht tp://rubyforge.org/docman/view.php/5/460/faq.html#anon_svn_failure)

Now if you run the command with the corrected http vs svn address you would get correct output:

$ svn log --revision 'HEAD:{2005-05-05}' ht tp://churn-demo.rubyforge.org/svn/audit
------------------------------------------------------------------------
r10 | marick | 2006-08-08 19:36:28 -0500 (Tue, 08 Aug 2006) | 1 line

------------------------------------------------------------------------
r9 | marick | 2006-08-08 19:35:36 -0500 (Tue, 08 Aug 2006) | 1 line

------------------------------------------------------------------------
r7 | marick | 2006-08-08 19:32:47 -0500 (Tue, 08 Aug 2006) | 1 line

------------------------------------------------------------------------
r3 | marick | 2006-08-07 23:22:26 -0500 (Mon, 07 Aug 2006) | 1 line

reversal story
------------------------------------------------------------------------
r1 | marick | 2006-08-07 14:21:47 -0500 (Mon, 07 Aug 2006) | 1 line

first touches
------------------------------------------------------------------------

Thus, in order to correct the output of churn, change your svn_log definition to have this definition of root:
root = "ht tp://churn-demo.rubyforge.org/svn"--Salman Ansari

#47934: I use Ruby 1.9.3 and when I try to run churn-tests.rb I get the error:

C:\Ruby193\code\churn>ruby churn-tests.rb
C:/Ruby193/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require': cannot load such file -- churn (LoadError)
from C:/Ruby193/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require' from churn-tests.rb:7:in `<main>'
C:\Ruby193\code\churn>

Is it because I use a different version of Ruby?--Nina Jareke

#44554: Half way through the page, the churn-tests.rb example that shows how to select specific tests has a technical error.

prompt> ruby churn-tests.rb --name=/asterisks/
should be
prompt> ruby churn-tests.rb --name /asterisks/
- just leave out the '=' after --name--Ben Cawrse

#31892: Paragraph : "Suppose that I later change month_before and
break it. Then both the direct test_header_format and [...]"

I disagree that the 'direct' test fails; the 'bootstrap' test_header_format
and the test_month_before_is_28_days will both fail.
--John H Simmonds

#50482: In the las line of svn_log says ‘svn log #{timespan} #{root}/#{subsystem}‘
The correct form is with "svn log #{timespan} #{root}/#{subsystem}" becose you use #{} for print values.--Matias Mascazzini

#27027: It seems I always get a svn syntax error unless I take off the single quotes around 'HEAD:{2005-01-26}'. This only returns a line of dashes from the repository though. I am very light on SVN, but I am wonder if the syntax is correct for my setup. I am running these scripts from the cmd line in Windows XP.--Bill

#34183: timespan = "-revision 'HEAD:{#{start_date}}'"
not only require 2 dashes, but enclosing the revision range in single quotes gives a syntax error from svn.--Garold L Johnson

#49637: The autor didn't mention that we would need subvertion installed. After getting the last version of that SVN (subvertion) I changed a bit the code to force it to work, I took out the single quotes around HEAD{#{start_date}} and instead of Time.now, I put Time.local(2005, 7, 30) (without those changes we couldn't follow along the book).

def month_before(a_time)
a_time - 28 * 24 * 60 * 60
end

def svn_date(a_time)
a_time.strftime("%Y-%m-%d")
end

def header(an_svn_date)
"Changes since #{an_svn_date}:"
end

def subsystem_line(subsystem_name, change_count)
asterisks = asterisks_for(change_count)
"#{subsystem_name.rjust(14)} #{asterisks} (#{change_count})"
end

def asterisks_for(an_integer)
'*' * (an_integer / 5.0).round
end

def change_count_for(name, start_date)
extract_change_count_from(svn_log(name, start_date))
end

def extract_change_count_from(log_text)
lines = log_text.split("\n")
dashed_lines = lines.find_all do | line |
line.include?('--------')
end
dashed_lines.length - 1
end

def svn_log(subsystem, start_date)
timespan = "--revision HEAD:{#{start_date}}"
root = "svn://rubyforge.org/var/svn/churn-demo"

`svn log #{timespan} #{root}/#{subsystem}`
end

if $0 == __FILE__
subsystem_names = ['audit', 'fulfillment', 'persistence',
'ui', 'util', 'inventory']
start_date = svn_date(month_before(Time.local(2005, 7, 30)))

puts header(start_date)
subsystem_names.each do | name |
puts subsystem_line(name, change_count_for(name, start_date))
end
end

besides that: Great book!! Thanks!!--Celso de Sá Lopes

#32550: Sentence "The special character + says that the preceding character must be repeated one or more times to match:"
Should read, "The special character + says that the preceding character MAY be repeated one or more times to match:"

(As it is currently stated, the example'abc' should not match since the b is not repeated)--Dan G

#27381: The bulleted list at the bottom of the page mixes up 1 and -1. The last sentence of the first bullet should read:

We'll want another to come first in the sorted list, which will happen if the block returns 1.

The second bullet should read:

The value of 3 <=> 5 is -1, meaning that 5 comes after 3 in the built-in ordering.

The third bullet should read:

If the block returned that -1...

The last bullet should read:

So we negate the result of <=> to convert the -1 into 1...--Evan A. Zacks

#43818: It's written twice that dot matches any character. This is not true, since it doesn't match newline. Compare the two following:

~>irb
irb(main):001:0> /a.b/ =~ "a\nb"
=> nil
irb(main):002:0> /a.b/m =~ "a\nb"
=> 0

I use the single-line mode flag (i.e. 'm') in the second case. This feature is sometimes called dot-matches-newline or dot-all.--Staffan Nöteberg

#31570: Amazon seems to have added some style sheets here. I had to modify the regex to include "span" like so: /<b.*?><span\sid.*?>(.*?)</span\s*>/

I suppose one could also use a greedy operator to find the second ">" before the group.--Ransom

#34135: I don't know if this is an error. I'm not able to use setup.rb. After I have run setup.rb I'm still not able to call clash-check.rb from an arbitrary folder. I'm on Mac OS X. I don't seem to have any site_local folder which is unfortunate since it is mentioned repeatedly. Files seems to installed in /System/Library/Ruby.framework... In Mac OS X Leopard ruby has been framwork'ized could this have something to do with my problems? --Johan Bjørn

#27020: I tried to use the "make-s4t-project.rb" script and got an error when trying to execute the default-project.rb script from the site_ruby folder (after running setup.rb). I am using Mac OSX 10.4 with ruby 1.8.5 (2006-12-25 patchlevel 12) [i686-darwin8.8.1].

/usr/local/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `gem_original_require': no such file to load -- s4t-utils/capturing-globals (LoadError)--Simon

#26933: There is a problem with the downloadable code described in this section. Two of the tests in s4t-utils fail on Windows (native Windows) when run in a directory containing a space its path. The tests pass from the same directory, when I change my path to use the "short format" names, which contain no spaces.--Marc Paterno

#28246: In figure 20.2, in the InnerModule definition, "def SomeClass" should be changed to "class SomeClass". This corresponds to line 44 of module-facts/some-module.rb.

--Evan A. Zacks

#27041: The solution to Exercise 3 in file exercise-3.rb in folder exercise-solutions/error-handling has an error. Note that you define your Reserver class as follows:

class Reserver
def reserve(machine_name)
machine = Machine.new(machine_name)
yield machine
puts "Reserved #{machine.name}."
machine
rescue Exception => ex
puts "Test failure: #{ex.message}"
ensure
release(machine) if machine
end

def release(machine)
puts "Released #{machine.name}."
end
end

You need to reverse the order of the following two lines of code:

yield machine
puts "Reserved #{machine.name}."

It should be:

puts "Reserved #{machine.name}."
yield machine

Otherwise, your output will never begin with:

Reserved Mycroft.

Nice exercise though.--Bharat Ruparel

#50321: suitcaseofcourage April 6th, 2009 6:14 am I strongly dgaisree with the Skype website being held up as any type of best practice. As good as the service is, the website is equally bad. Nearly impossible to find your way around, and actually sign up for the services you want. And whenever I click on shop, for some reason it takes me to the Japanese version. Has been that way for a few years. Am I the only one who sees that? That site is terrible, although it looks pretty if you aren't actually trying to accomplish anything.--GIdDhCcy