Nabble - ruby-talk

Re: Heatmaps in Ruby

2009-11-26T15:31:53Z

On Thu, Nov 26, 2009 at 8:43 AM, Marc Hoeppner
<marc.hoeppner@...> wrote:

> Hi,
>
> I am currently thinking about doing a heatmap for data visualization,
> but I have very little experience with any type of graphical tools in
> ruby (like the various SVG libs etc).
>
> So I was hoping someone could point me in the right direction and save
> me some time trying out useless libraries ;) Doesn't have to be ruby
> either, but that way I could probably integrate it more easily into my
> analysis pipeline.
>

http://blog.revolution-computing.com/2009/11/charting-time-series-as-calendar-heat-maps-in-r.html

I think there are ruby bindings for R too, so that may help.

Best regards,
Michael Guterl

Re: invalid date error when installing syntax gem

2009-11-26T14:35:10Z

On Nov 4, 6:14 am, Joel VanderWerf <vj...@...> wrote:

> Joel VanderWerf wrote:
>
> > Anyone else getting this error? I didn't find any recent mention of it.
>
> > gem install syntax --backtrace
> > ERROR: While executing gem ... (ArgumentError)
> > invalid date
>
> Forgot to say: this is the only gem with this problem. I set up a new
> system today with about 40 other gems that installed fine, except the
> ones dependent on syntax.
>
> There's no improvement when downloading the gem file and installing it.
> The same version of syntax (1.0.0) has worked for me before, with the
> same versions of ruby and gem.
>
> $ ruby -v
> ruby 1.8.6 (2008-08-11 patchlevel 287) [i686-linux]
> $ gem --version
> 1.3.5
>
> However, I'm using gcc 4.4.1 for the first time (ubuntu 9.10).
>
> --
> vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407

Hi,

I was getting the same error when installing cucumber (it depends on
diff-lcs, which depends on syntax). And after a few long hours of
fighting with this bug I have found a solution!

It turns out there is a bug in ruby 1.8.6 for 64 bit architecture. And
guess what, the problem is with date. You can read more about the bug,
and the solution, here: http://redmine.ruby-lang.org/issues/show/1735.
So, to solve the problem I had to compile ruby myself. Here are the
steps I did:

1) wget ftp://ftp.ruby-lang.org/pub/ruby/1.8/ruby-1.8.6-p286.tar.gz
2) tar zxf ruby-1.8.6-p286.tar.gz
3) cd ruby-1.8.6-p286

Now I changed some ext settings, as described here: http://blog.ghandal.net/2009/01/

4) vim ext/Setup, and uncomment some extensions:

#Win32API
#bigdecimal
curses
#dbm
digest
digest/md5
#digest/rmd160
digest/sha1
digest/sha2
dl
enumerator
#etc
#fcntl
#gdbm
iconv
#io/wait
#nkf
#pty
openssl
#racc/cparse
readline
#sdbm
socket
stringio
strscan
syck
syslog
#tcltklib
thread
#tk
#win32ole
zlib

5) ./configure --prefix=/usr/local --with-openssl-dir=/usr --with-
readline-dir=/usr --with-zlib-dir=/usr

This assumes ruby will be install under /usr/local

Now before you run make, you MUST apply the fix from here:
http://redmine.ruby-lang.org/issues/show/1735

6) vim Makefile

and apply the fix:

- CFLAGS = -g -O2 -DRUBY_EXPORT -D_GNU_SOURCE=1
+ CFLAGS = -g -DRUBY_EXPORT -D_GNU_SOURCE=1

save the file and then

7) make
8) sudo make install

Then I would suggest installing rubygems manually:

9) wget http://rubyforge.org/frs/download.php/60718/rubygems-1.3.5.tgz
10) tar zxf rubygems-1.3.5.tgz
11) cd rubygems-1.3.5/
12) sudo ruby setup.rb

Now you should be all set and ready to install the syntax gem, and any
others than depend on it, like cucumber in my case.

Wow, I must admit that was my longest ruby installation ever ...

Good luck!

Kind regards,
Marcin Domanski

Re: Help with regex

2009-11-26T13:55:28Z

s = "Text1\n
Text2\n
Text3---"

irb(main):036:0> s.scan( /(\w+?)(?:\n|-+)/ )
=> [["Text1"], ["Text2"], ["Text3"]]

Usually, it's easier to use scan when you feel your code in the Regexp gonna
be repeated.
If the text is so simple, you could iterate which String#each_line, and then
remove any '-' at the end.

2009/11/26 Lucas Fialho <lucasfazprograma@...>

> Hello everyone.
> I'm trying to match the following pattern:
>
> Text1\n
> Text2\n
> Text3---
>
> Please note that Text3 can contain \n.
> I tried using this regex:
>
> /(.*?)\n(.*?)\n(.*?)---/
>
> The pattern matches and I have three matches, but they're like this:
>
> match[0] => "Text2\nText3---"
> macth[1] => 'Text2'
> match[2] => 'Text3'
>
> How can I get the first one to be 'Text1' ?
>

Re: Help with regex

2009-11-26T13:51:35Z

try putting word metacharacter instead of an any metacharacter

\w*

instead of

.*

2009/11/26 Lucas Fialho <lucasfazprograma@...>

Re: Pattern match to fail if two periods in a row

2009-11-26T13:49:22Z

so then only trying to match:

/\w+\.?\w*/

should do

2009/11/26 Ralph Shnelvar <ralphs@...>

>
> >>> "abc..def" !~ /\.\./
> =>> false
>
> I don't think that
> "abc..def" !~ /\.\./
> is a regular expression.
>
> /\.\./
> is a regular expression.
>
>
> Basically ... I need something that will work in a Rails
> validates_format_of
>
> # Reject if the email address has two periods in a row
> validates_format_of :email,
> # See http://en.wikipedia.org/wiki/E-mail_address
> :with => ????,
> :message => 'invalid email format'
>
>
>
>
>
>

Help with regex

2009-11-26T13:28:37Z

Hello everyone.
I'm trying to match the following pattern:

Text1\n
Text2\n
Text3---

Please note that Text3 can contain \n.
I tried using this regex:

/(.*?)\n(.*?)\n(.*?)---/

The pattern matches and I have three matches, but they're like this:

match[0] => "Text2\nText3---"
macth[1] => 'Text2'
match[2] => 'Text3'

How can I get the first one to be 'Text1' ?

Ruby byte access to disk sectors like dd does

2009-11-26T13:07:20Z

I have been unable to find any reference to Ruby methods that provide
raw disk access the way dd does. I frequently use the Linux utility
program, dd, and would like to be able to do the same type of byte-level
and sector-level access to the hard drive with Ruby. (What I am looking
for is not file access.) Are there Ruby methods to provide this
capability (other than having Ruby access dd)?

Thanks,
Gary
--
Posted via http://www.ruby-forum.com/.

Re: Net::Telnet - How to send keystrokes like ESC

2009-11-26T12:46:58Z

Babu Raj wrote:
> Hi
> Could you pls let me know how I can send in keystrokes such as ENTER and
> ESC to a telnet session. I have the session created using
> Net::Telnet.new().

Have you tried

sess.puts

sess.print "\x1b"

?
--
Posted via http://www.ruby-forum.com/.

Re: Pattern match to fail if two periods in a row

2009-11-26T12:46:06Z

>>> "abc..def" !~ /\.\./
=>> false

I don't think that
"abc..def" !~ /\.\./
is a regular expression.

/\.\./
is a regular expression.

Basically ... I need something that will work in a Rails validates_format_of

# Reject if the email address has two periods in a row
validates_format_of :email,
# See http://en.wikipedia.org/wiki/E-mail_address
:with => ????,
:message => 'invalid email format'

Re: Net::Telnet - How to send keystrokes like ESC

2009-11-26T12:32:41Z

On Nov 26, 2009, at 06:28 , Babu Raj wrote:

> Could you pls let me know how I can send in keystrokes such as ENTER and
> ESC to a telnet session. I have the session created using
> Net::Telnet.new().

Depends on what you're trying to do. Either something like this:

http://groups.google.com/group/ruby-talk-google/browse_frm/thread/96cabb08c34182c/77c0843d27e95dd3?lnk=gst&q=berger+password&rnum=1#77c0843d27e95dd3

or you want to look at expect.rb.

Re: Pattern match to fail if two periods in a row

2009-11-26T12:14:08Z

if ! /\.{2,}/

or something

2009/11/26 Ralph Shnelvar <ralphs@...>

> Ok ... I really tried. And I used http://rubular.com/ (really nice)
>
> And I read and reread the pickaxe book section on regular
> expressions.
>
> In other words ... I tried.
>
> So ..
>
> How does one create an expression that fails if there are two or more
> periods
> (e.g. "..") in a row?
>
>
>

Re: Pattern match to fail if two periods in a row

2009-11-26T12:12:16Z

On Thu, Nov 26, 2009 at 8:51 PM, Ralph Shnelvar <ralphs@...> wrote:

>> "abc..def" !~ /\.\./
=> false

One easy way is to use the negated match operator (!~). Then the
regexp is trivial.

Jesus.

Pattern match to fail if two periods in a row

2009-11-26T11:51:02Z

Ok ... I really tried. And I used http://rubular.com/ (really nice)

And I read and reread the pickaxe book section on regular
expressions.

In other words ... I tried.

So ..

How does one create an expression that fails if there are two or more periods
(e.g. "..") in a row?

Re: Ruby a good choice for CGI?

2009-11-26T09:40:33Z

> Ok I tried sinatra. It seems like it fires up webrick on port 4567, so I
> take it there's some config file I need to mess with, or my hosting
> provider deals with so it'll run on Apache instead?

If you have a Rails hosting provider, they can probably host Sinatra
too. Both just run on top of Rack.

If your hosting provider uses Phusion Passenger (= mod_rails), that can
host Sinatra.
http://www.modrails.com/documentation/Users%20guide%20Apache.html#_sinatra

If you have a totally generic hosting provider then you may be stuck
running your app as a cgi-bin or fastcgi (although obviously they'll
still have to provide you with a ruby interpreter). That may be enough
to get you started, but you'd probably be best changing to a different
hosting provider longer term.

I've run small fastcgi apps successfully; experience from many Rails
users has been that it has a tendency to explode. As a result, most ruby
people (and developers) are staying away from fastcgi. But it still
*should* be possible to build rack to work under fastcgi; see the README
in the rack gem. You'll need the ruby fcgi gem, which in turn depends on
the C fcgi library.

> Also, I can hit my sinatra ruby script from my browser, but when I tried
> to hit it from a jQuery AJAX request, I get nothing back and the sinatra
> console says that it was an OPTIONS request instead of the GET request

No idea on that. It all works for me. Use tcpdump to prove or disprove
that jQuery is sending an OPTIONS request; that would show if it's a
problem with your jQuery code.

> So I can just use the Sinatra lib to route the request, deal with
> cookies and sessions, and then hand it to my hosting provider and
> they'll set it up properly?

Depends on how clued up and helpful your hosting provider is :-)

> if one person
> requested it, it started running, hitting the db etc, and then another
> person requested it before it was finished, what happens?

Sinatra has a request lock turned on by default, so that the second
request will wait until the first completes, but you can turn it off if
you are sure your application is thread-safe.

However, running under fastcgi or mod_rails, only one request would be
sent at a time to your application. Therefore you will need to spawn
multiple processes to handle concurrent requests. This should be done
for you, but you may wish to tune the parameters for min/max processes
spawned.
--
Posted via http://www.ruby-forum.com/.

Re: Ruby a good choice for CGI?

2009-11-26T09:11:17Z

Seebs wrote:

> On 2009-11-25, Nick Dr <nickhannum@...> wrote:
>> Can someone point me in the right direction here? My app is VERY small.
>> Practically no code, no HTML output. All I need is to execute the 2 or 3
>> Ruby functions I already have, on the net, with some basic
>> cookie/session support. What's the least headache(and not terribly slow)
>> way to do this?
>
> How many hundred thousand hits a day do you have to process?
>
> If the answer is "less than one", you probably don't care much about
> speed in practice.
>
> Past that... If you want something more interesting, I am pretty happy
> with rails/passenger. Relatively low setup effort and works great, and
> while it might be overkill for what you want to do, I really do find
> it pretty rewarding.

Well, HOPEFULLY I'm expecting a lot of hits, but these scripts will also
be available via a facebook app, so hopefully the time zones will spread
it out for me, and I'll be getting several hit per minute, 24/7, but
never a lot at once.

That brings up another question I had. Does
FastCGI/Mongrel/Thin/Passenger deal with multithreading for me? Like if
two people request an HTML page I figure it can just serve two copies of
it. But what about scripts? In theory my scripts only take milliseconds
from request to response, but just for arguments sake, if one person
requested it, it started running, hitting the db etc, and then another
person requested it before it was finished, what happens?

--
Posted via http://www.ruby-forum.com/.

Re: Ruby a good choice for CGI?

2009-11-26T09:08:04Z

On Thu, Nov 26, 2009 at 5:03 PM, Nick Dr <nickhannum@...> wrote:
> =
>> That sounds tailor-made for Sinatra. However, you should learn something
>> about
>> REST, first -- are you sure POST is appropriate?
>
> Ok I tried sinatra. It seems like it fires up webrick on port 4567, so I
> take it there's some config file I need to mess with, or my hosting
> provider deals with so it'll run on Apache instead?

You can use Sinatra with JRuby to host the app via Google AppEngine,
that seems quite elegant. I don't know how AppEngine's pricing
compares to your other hosting offer of course.

http://blog.bigcurl.de/2009/04/running-sinatra-apps-on-google.html

--
Paul Smith
http://www.nomadicfun.co.uk

paul@...

Re: Ruby a good choice for CGI?

2009-11-26T09:03:41Z

=
> That sounds tailor-made for Sinatra. However, you should learn something
> about
> REST, first -- are you sure POST is appropriate?

Ok I tried sinatra. It seems like it fires up webrick on port 4567, so I
take it there's some config file I need to mess with, or my hosting
provider deals with so it'll run on Apache instead?

Also, I can hit my sinatra ruby script from my browser, but when I tried
to hit it from a jQuery AJAX request, I get nothing back and the sinatra
console says that it was an OPTIONS request instead of the GET request
it reports when firefox asks for the page. What am I doing wrong here?
The idea was to jquery post to a ruby script for some JSON data and then
update my canvas based on that data.

> FastCGI is obsolete, so scratch that.

The host I was considering, HostingRails, says they'll do a FastCGI
deployment for me. I am (hopefully) expecting pretty high frequency
traffic. Like several hits/min 24/7, but never > 1000 hits per minute,
because this will be a global app available via facebook, so the time
zones should spread it out for me.
Are you sure FastCGI isn't a good option for this?

> Passenger and mod_ruby are essentially the same thing, IIRC. But my
> understanding is that Passenger works with Rack, which doesn't feel at
> all
> like CGI. So these might be deployment options, but they have nothing to
> do
> with how you write and develop your app.

So I can just use the Sinatra lib to route the request, deal with
cookies and sessions, and then hand it to my hosting provider and
they'll set it up properly?

Thanks for all the advice!
--
Posted via http://www.ruby-forum.com/.

fft for Ruby?

2009-11-26T07:20:13Z

Anyone know any library for Ruby that implements low level fft n-
dimensional algorithm?

Dalthon

Module.nesting strangeness

2009-11-26T06:53:42Z

Hi,
i'm encountering a weird behavior of the Module.nesting methodd. Here is
my testcase from the irb:

____________________________

class A
class B
def test()
puts "Module.nesting : " + Module.nesting * ","
end
end
end
=> nil

b = A::B.new
=> #<A::B:0x24102d8>

b.test
Module.nesting : A::B,A
=> nil

b.instance_eval { puts "Module.nesting : " + Module.nesting * "," }
Module.nesting :
=> nil
____________________________

The documentation says : "Returns the list of Modules nested at the
point of call. ". But how Module.nesting in test() method knows that it
was declared inside the class A/classB and not outside?
--
Posted via http://www.ruby-forum.com/.

Re: problem with gempath

2009-11-26T06:45:11Z

Just fix it.
GEM_PATH env var was set by rvm (http://rvm.beginrescueend.com/).

On 18 nov, 19:21, jney <jeansebastien....@...> wrote:

> Hi jan-Erik, i should precise that, gempath isn't define in my
> ~/.gemrc
>
> On 18 nov, 18:53, Jan-Erik Rediger <bad...@...> wrote:
>
> > On Thu, Nov 19, 2009 at 02:40:06AM +0900, jney wrote:
> > > hi, I recently got problem with installing gem. when i execute "gem
> > > install xxx" it install to the current directory.
> > > here is what i've got when i execute "gem env"
>
> > > - GEM PATHS:
> > > -
> > > - /Users/jsney/.gem/ruby/1.8
> > > - /opt/local/lib/ruby/gems/1.8
>
> > > i don't know how to remove the first record. anyone can help ?
>
> > if it is in your ~/.gemrc then editing this file should help
>
> > badboy_
>
>

Just fix it.
GEM_PATH env var was set by rvm (http://rvm.beginrescueend.com/).

creating certificates and public and private keys

2009-11-26T06:37:10Z

Hi im going to have to create a lot of public and private keys for
clients and would like to automate the process by using a script (in
ruby of course).

This is for an openvpn setup and currently ive been MANUALY creating
keys with the easy-rsa bat file that comes with it but id like to
automate it.

Is there a ruby libary available that would allow me to create public
and private keys if i already have a CA. Would openvpn recognize these
keys (are keys, keys no matter what language they are created in??? im
not hot on cryptology)

The other option would be to just execute the bat file from my ruby
script and simulate the keyboard to respond to the various prompts. I
havent doent this before so im not sure if this is easier or harder than
above. Any tips or pointers will really help!
--
Posted via http://www.ruby-forum.com/.

Re: Ruby a good choice for CGI?

2009-11-26T06:33:31Z

Brian Candler wrote:

> Marnen Laibow-Koser wrote:
>> And running multiple Rails apps with one Passenger installation is
>> likwise a breeze.
>
> - although there's some possibility for interaction between them. In
> particular, PassengerUseGlobalQueue gives one global queue across all
> apps, rather than one queue per application. Also,
> PassengerMaxInstancesPerApp can only be set globally rather than per
> app.
>
> At least it was like that last time I enquired, but the current
> documentation suggests this is still the case.

I think it may not be, but don't quote me. :)

Best,
--
Marnen Laibow-Koser
http://www.marnen.org
marnen@...
--
Posted via http://www.ruby-forum.com/.

Net::Telnet - How to send keystrokes like ESC

2009-11-26T06:28:23Z

Hi
Could you pls let me know how I can send in keystrokes such as ENTER and
ESC to a telnet session. I have the session created using
Net::Telnet.new().
--
Posted via http://www.ruby-forum.com/.

Re: DRB class in array

2009-11-26T06:09:06Z

Master Marv wrote:
>> include DRbUndumped
> this seems to let the class reside wherever it has been generated.
> is it possible to generate a class on a drb client, copy it to the
> server and then let it stay there (ie. further interaction with the
> class should be made with the the class on the server and not with local
> copies).

DRb has no real concept of a "server" or a "client" - connections can be
opened and method calls made from either side.

You could originate your object, pass it across to another place, and at
that point do
obj.extend DRbUndumped
which will lock it there.

But perhaps more sensible is to pass across the *parameters* needed to
make the object, i.e. have a class method on the server such as

def Foo.make_status(*args)
IEB_wrapper1.new(*args)
end

and you share the Foo object via DRb.
--
Posted via http://www.ruby-forum.com/.

Heatmaps in Ruby

2009-11-26T05:43:29Z

Hi,

I am currently thinking about doing a heatmap for data visualization,
but I have very little experience with any type of graphical tools in
ruby (like the various SVG libs etc).

So I was hoping someone could point me in the right direction and save
me some time trying out useless libraries ;) Doesn't have to be ruby
either, but that way I could probably integrate it more easily into my
analysis pipeline.

Thanks,

Marc
--
Posted via http://www.ruby-forum.com/.

Re: DRB class in array

2009-11-26T05:06:56Z

> include DRbUndumped
this seems to let the class reside wherever it has been generated.
is it possible to generate a class on a drb client, copy it to the
server and then let it stay there (ie. further interaction with the
class should be made with the the class on the server and not with local
copies).

what i want to do is the following:
i have a class that has a run and a status function. when the run
function is invoked the class computes something for ~5minutes.
the calculation should happen on the drb server.
multiple drb clients should generate classes on the server(or locally
and copy them to the server), so that the server does the computation.
after the jobs have been started (remote_job_array[x].start) the clients
terminate. other clients that should check the status of the computation
via a status function (remote_job_array[x].status) of the class on the
server.
--
Posted via http://www.ruby-forum.com/.

Net::SSH and STDIN / Pending jobs

2009-11-26T05:01:27Z

Hi,

I am writing a library that allows the user to run some commands over
SSH into a server and I have two problems right now:

1) The code get stuck whenever the executed code needs STDIN, it just
sits there. How can I indicate that my STDIN is not interactive using
Net::SSH?

2) When the user runs background jobs (like nohup
/etc/init.d/start-something &) the script just sits there as well,
waiting for jobs to finish.

Considering the script that is executed is a user input and, being so, I
don't have control over it, what would be the best way to avoid those 2
issues?

Thanks a lot!

Best regards,
Felipe.
--
Posted via http://www.ruby-forum.com/.

--
Felipe Gonçalves Coury
Software Engineer and Java Specialist
contact@felipecoury.com
Mobile: +55 19 9305-3619
Home: +55 19 3307-2982

Hey, visit my blogs:
http://blogs.felipecoury.com
http://felipecoury.wordpress.com

Re: Mocha multiple_yields with arrays

2009-11-26T04:36:17Z

2009/11/26 Raymond O'Connor <nappin713@...>:
> I believe there's a bug in mocha that causes an unnecessary and annoying
> warning message. If you call multiple_yields with arrays as the arg you
> want yielded it will complain.
>
> object.multiple_yields([1,2], [3,4], [5,6])
>
> => prints a warning to the effect: "multiple values for a block
> parameter 2 for 1"

That code snippet looks wrong. The multiple_yields method is a method
on an expectation, so you must call it on the result of e.g.
object.stubs or object.expects. I suspect this was a typo and assume
you meant something more like this :-

object.stubs(:wibble).multiple_yields([1,2], [3,4], [5,6])

In this case, Mocha will invoke the block supplied to the wibble
method 3 times and passing in 2 parameters on each invocation.

If you supply a block which defines only one parameter you will see
the warning you described :-

parameters = []
object.wibble { |parameter| parameters << parameter }
# => warning: multiple values for a block parameter (2 for 1)
p parameters # => [[1,2], [3,4], [5,6]]

If you supply a block which defines two parameters you will not see
the warning :-

parameters = []
object.wibble { |parameter_1, parameter_2| parameters <<
[parameter_1, parameter_2] }
p parameters # => [[1,2], [3,4], [5,6]]

So the warning you are seeing is not a problem with Mocha, but due to
normal Ruby behaviour which you can see in irb :-

irb> def wibble
irb> yield(1,2)
irb> end
=> nil
irb> wibble { |x| p x }
(irb):4: warning: multiple values for a block parameter (2 for 1)
from (irb):2
[1, 2]
=> nil
irb> wibble { |x,y| p [x,y] }
[1, 2]
=> nil
irb> wibble { |(x,y)| p [x,y] }
[1, 2]
=> nil

I hope this helps. If you have any further questions about this,
please post to the Mocha mailing list [1] which would be a more
appropriate forum.

Cheers, James.

[1] http://groups.google.com/group/mocha-developer

Re: Distinct Sets (#225)

2009-11-26T03:22:14Z

Here is my array-based combination solution:

def multiple(start)
sets = start.uniq
while (f=sets.flatten) && f != f.uniq
sets.combination(2) { |(a, b)|
if sets.include?(a) && sets.include?(b) && a != b && (a &
b).length > 0
# include? ensure the set has not been mixed with another
one already
# a != b ensure we are not playing with a == b, what would
delete a (and b) or not find the index
sets[sets.index(a)] = (a | b)
sets.delete(b)
end
}
end
sets.map { |s| s.sort }
end

It just combinate by 2 sets, and look if they can merge.
The while loop is then rarely met, because sets merge 2 by 2.

This solution is quite fast for small sets(as I said before, 0.22 for the
first test), but is completely out for larger sets.

This is another, using Array#partition to modify itself, while merging all
the elements with the common value in one iteration

def better(start)
sets = start.dup
f = sets.flatten
(f.uniq.select { |e| f.count(e)>1 }).each { |reducing_on|
i = sets.index { |set| set.include? reducing_on }
sets2merge, sets = sets.partition { |set| set.include? reducing_on }
sets.insert( i, sets2merge.inject(:|) )
}
sets.map { |s| s.sort }
end

2009/11/26 lith <minilith@...>

> > > Here is a graph-based approach:
> > >http://pastie.org/714759
> >
> > Running the small approximative benchmark:
>
> Here is a modified version that should have slightly improved runtime
> characteristics:
> http://pastie.org/715755
>
> Regards,
> Tom
>
>

Re: DRB class in array

2009-11-26T02:30:57Z

Master Marv wrote:

> if a client modifies the status variable of a class instance in the
> array it does not get changed.
>
> dump = DRbObject.new nil, ARGV.shift
> myclass = IEB_wrapper1.new
> dump.push myclass
> dump[0].status = "Hello"
> p dump[0].status => results in "ready" not in "Hello"
>
> how can i modify the status of my class in the array on the drb server?

class IEB_wrapper1
include DRbUndumped
end

This means that instead of passing across a *copy* of the object (made
using Marshal.dump and load), it will pass across a DRb *proxy object*.
All operations made on that proxy are sent across as remote method calls
and therefore made on the server.

I wrote a document called "DrbTutorial" on rubygarden.org, which
unfortunately is long since gone. You might be able to find a cached
copy somewhere.
--
Posted via http://www.ruby-forum.com/.

Re: Difference between << and += for Strings and Arrays. Bug?

2009-11-26T02:16:40Z

2009/11/26 Robert Klemme <shortcutter@...>:
> As far as I can see you only need an inclusion check not the complete
> list of ancestors. A simple iterative solution with a BFS could do
> the job for you

Here's a more modularized version:

require 'set'

def ancestor_bfs
visited = Set.new
queue = [self]

until queue.empty?
n = queue.shift

if visited.add? n
yield n
queue.concat(n.ancestors)
end
end

false
end

def ancestor?(candidate)
ancestor_bfs {|n| return true if candidate == n}
false
end

# or even without a method but still fast exit when the node is found:
folder.to_enum(:ancestor_bfs).any? {|n| candidate == n}

# fully modularized

def bfs(next_meth, start = self)
visited = Set.new
queue = [start]

until queue.empty?
n = queue.shift

if visited.add? n
yield n
queue.concat(n.send(next_meth))
end
end

false
end

def bfs_ancestors(&b)
bfs(:ancestors, &b)
end

Now you can do

class Integer
def n; [self * 2, self * 2 + 1] end
end

irb(main):057:0> bfs(:n, 3) {|x| p x; break if x > 20}
3
6
7
12
13
14
15
24
=> nil
irb(main):058:0>

:-)

Cheers

robert

--
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

DRB class in array

2009-11-26T02:08:02Z

hi,
i would like to store an array of this very simple class on a drb server

class IEB_wrapper1
attr_accessor :status

def initialize
@status="ready"
end
end

the object on the drb server is an array:
dump=[]
DRb.start_service "druby://BLA:55555", dump

if a client modifies the status variable of a class instance in the
array it does not get changed.

dump = DRbObject.new nil, ARGV.shift
myclass = IEB_wrapper1.new
dump.push myclass
dump[0].status = "Hello"
p dump[0].status => results in "ready" not in "Hello"

how can i modify the status of my class in the array on the drb server?
--
Posted via http://www.ruby-forum.com/.

Re: Ruby gem , require and version problem

2009-11-26T02:07:06Z

On Nov 26, 2009, at 00:59 , Marc Hoeppner wrote:

> require 'rubygems'
> gem 'ruby-foo-bar', '0.9.2'
>
> That doesn't throw an error, but the game is apparently not loaded as
> the modules and classes are not recognized subsequently.

gem doesn't load any files, it just activates the right gem.

require 'rubygems'
gem 'ruby-foo-bar', '0.9.2'
require 'bar'

Re: Difference between << and += for Strings and Arrays. Bug?

2009-11-26T01:28:24Z

2009/11/26 Pieter Hugo <pieter@...>:

> Hi Robert (and everyone else) - thanks for the well reasoned responses.
> I'll get the hang of it I'm sure
>
>> Why do you want to have two copies of your Array?
>
> I have a setup where I have Folder objects. A folder can have many other
> children (members) as sub folders, but it can also have many other
> folders as parents (groups it belongs to). I get this done via a
> crosslink table. When creating a new parent-child relationship I need to
> make sure that the child is not somehow an ancestor or the parent I am
> trying to subordinate it to (as I need to avoid circular reference)
>
> So I wrote the folder function:
>
> def ancestors
> ancestors = self.groups #all the immediate parents are obviously
> ancestors
> scanfolders = [] #set up a stack to iterate through,
> #looking for grandparents etc
> scanfolders += ancestors #the stack starts with the current ancestors
> if !scanfolders.nil? then
> while scanfolders.length > 0 do # while there are items on the stack
> scanitem = scanfolders.pop # get the last one and reduce the stack
> if scanitem then
> if !scanitem.groups.nil? then #if this item has parents
> #add them to the stack
> scanfolders += scanitem.groups
> scanfolders.uniq!
> ancestors += scanitem.groups #and record this item as an
> #ancestor
> ancestors.uniq!
> end
> end
> end
> end
> return ancestors
> end
>
> So - to answer the question - I need to arrays that are initially the
> same (direct parents), But the one will eventually contain all ancestors
> and the other will be empty after iterating through all ancestors and
> testing them for further ancestors.

As far as I can see you only need an inclusion check not the complete
list of ancestors. A simple iterative solution with a BFS could do
the job for you

require 'set'

def ancestor?(candidate)
visited = Set.new
queue = [self]

until queue.empty?
n = queue.shift

if visited.add? n
return true if candidate == n
queue.concat(n.ancestors)
end
end

false
end

Note: I prefer a BFS over a DFS in these cases because the stack depth
is far more limited than the memory:

10:26:50 ~$ ruby19 -e 'def r(x) p x; r(x+1) end; r 0' | tail -3
-e:1:in `r': stack level too deep (SystemStackError)
from -e:1:in `r'
from -e:1:in `r'
from -e:1:in `r'
from -e:1:in `r'
from -e:1:in `r'
from -e:1:in `r'
from -e:1:in `r'
from -e:1:in `r'
... 8175 levels...
from -e:1:in `r'
from -e:1:in `r'
from -e:1:in `r'
from -e:1:in `<main>'
8184
8185
8186
10:27:04 ~$ ruby -e 'def r(x) p x; r(x+1) end; r 0' | tail -3
-e:1:in `inspect': stack level too deep (SystemStackError)
from -e:1:in `p'
from -e:1:in `r'
from -e:1:in `r'
from -e:1
12623
12624
12625
10:27:08 ~$

Kind regards

robert

http://en.wikipedia.org/wiki/Breadth-first_search

--
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

Re: Difference between << and += for Strings and Arrays. Bug?

2009-11-26T01:17:22Z

Pieter Hugo wrote:
> So I wrote the folder function:
>
> def ancestors

For me the natural way to do this would be recursively, but an iterative
solution is of course fine, and probably more efficient anyway.

As for your problem of not modifying the 'groups' array you are looking
at, I'd suggest:

scanfolders = []
scanfolders.concat(ancestors)
...
scanfolders.concat(scanitem.groups)

This creates a new array (scanfolders), then mutates that array by
tacking on the contents of some other array, without modifying that
other array. The first two lines could also be scanfolders =
ancestors.dup of course.

Not that there's anything really wrong with scanfolders += foo. It's
just that if you're going to be mutating this array (with pop), then you
might as well go for mutation across the board. It's also more efficient
if this array becomes large, as there's less array copying and object
creation going on.

> scanfolders = [] #set up a stack to iterate through,
> #looking for grandparents etc
> scanfolders += ancestors #the stack starts with the current ancestors
> if !scanfolders.nil? then

I observe that this condition is *always* true, since scanfolders is
never nil, so can be removed.

Other ways you can simplify your code:

> while scanfolders.length > 0 do # while there are items on the stack

one option: until scanfolders.empty?

> while scanfolders.length > 0 do # while there are items on the stack
> scanitem = scanfolders.pop # get the last one and reduce the stack
> if scanitem then

If your scanfolders never contains any nil items (and I don't see why it
should), then all three lines could shrink to

while scanitem = scanfolders.pop

> if !scanitem.groups.nil? then #if this item has parents
> #add them to the stack

if scanitem.groups

> scanfolders += scanitem.groups
> scanfolders.uniq!
> ancestors += scanitem.groups #and record this item as an
> #ancestor
> ancestors.uniq!

The problem I see here is that you might already have scanned a folder
and popped it from scanfolders, then add it back again, therefore
scanning it extra times unnecessarily. I can't convince myself whether
there is a possibility of ending up in an infinite loop.

One solution is to keep an explicit mark of folders you have traversed
(e.g. a hash of folder => true)

But since everything you've added to scanfolders has been added to
ancestors already, it may be sufficient to do:

scanfolders += scanitem.groups
scanfolders -= ancestors
ancestors += scanitem.groups

Or something like that. Actually I'm not sure if there's a mutating
version of -=

Regards,

Brian.
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