hi everyone,
what does `returning` do? it is used as
returning code =[] {
code << "something"
code << "another thing"
}
in what way it is different than?
code = []
code << "something"
code << "another thing"
thanks in advance
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On 11/15/05, Onur Turgay <onurturgay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:> hi everyone, > > what does `returning` do? it is used as > > returning code =[] { > code << "something" > code << "another thing" > }That''s not valid Ruby. I have no idea what that is supposed to do.> in what way it is different than? > > code = [] > code << "something" > code << "another thing"The previous code section is not valid. This code section is valid. :-)
Hi ! 2005/11/15, Joe Van Dyk <joevandyk@gmail.com>:> On 11/15/05, Onur Turgay <onurturgay@gmail.com> wrote: > > returning code =[] { > > code << "something" > > code << "another thing" > > } > > That's not valid Ruby. I have no idea what that is supposed to do.Hmmm, shouldn't that evaluate to something like this: returning( code=[] do code << 'something' code << 'another thing' end ) Although I agree that the first syntax doesn't properly evalutate in irb... Anyway, see ActiveSupport: # A Ruby-ized realization of the K combinator, courtesy of Mikael Brockman. I did find http://wiki.tcl.tk/1923 which talks about it. Bye ! -- François Beausoleil http://blog.teksol.info/ _______________________________________________ Rails mailing list Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org http://lists.rubyonrails.org/mailman/listinfo/rails
you can see the code in typo helpers :) it''s valid. be sure :) On 11/15/05, Joe Van Dyk <joevandyk-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:> > On 11/15/05, Onur Turgay <onurturgay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote: > > hi everyone, > > > > what does `returning` do? it is used as > > > > returning code =[] { > > code << "something" > > code << "another thing" > > } > > That''s not valid Ruby. I have no idea what that is supposed to do. > > > in what way it is different than? > > > > code = [] > > code << "something" > > code << "another thing" > > > The previous code section is not valid. This code section is valid. :-) > _______________________________________________ > Rails mailing list > Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org > http://lists.rubyonrails.org/mailman/listinfo/rails >_______________________________________________ Rails mailing list Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org http://lists.rubyonrails.org/mailman/listinfo/rails
does anyone understand what does it write in `K` page :) I have no clue On 11/15/05, Francois Beausoleil <francois.beausoleil-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:> > Hi ! > > 2005/11/15, Joe Van Dyk <joevandyk-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>: > > On 11/15/05, Onur Turgay <onurturgay-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote: > > > returning code =[] { > > > code << "something" > > > code << "another thing" > > > } > > > > That''s not valid Ruby. I have no idea what that is supposed to do. > > Hmmm, shouldn''t that evaluate to something like this: > > returning( > code=[] do > code << ''something'' > code << ''another thing'' > end > ) > > Although I agree that the first syntax doesn''t properly evalutate in > irb... > > Anyway, see ActiveSupport: > # A Ruby-ized realization of the K combinator, courtesy of Mikael > Brockman. > > I did find http://wiki.tcl.tk/1923 which talks about it. > > Bye ! > -- > François Beausoleil > http://blog.teksol.info/ > > _______________________________________________ > Rails mailing list > Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org > http://lists.rubyonrails.org/mailman/listinfo/rails > > >_______________________________________________ Rails mailing list Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org http://lists.rubyonrails.org/mailman/listinfo/rails
I need functionality for the equivalent of a servlet in Java. Specifically, I''m writing a monitoring application. This monitoring applicaiton will be a web service hosted in rails, as well as a UI. but I also need to run a timer in a "servlet" that triggers polling various resources to make sure they are running properly. This servlet needs to be loaded and started when the web server (webrick) is loaded and the timer will be started when the servlet is loaded. Could someone point me the right direction? Thanks, phil _______________________________________________ Rails mailing list Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org http://lists.rubyonrails.org/mailman/listinfo/rails
On 16/11/2005, at 9:57 AM, Phil Swenson wrote:> I need functionality for the equivalent of a servlet in Java… > > Specifically, I’m writing a monitoring application. This > monitoring applicaiton will be a web service hosted in rails, as > well as a UI… but I also need to run a timer in a “servlet” that > triggers polling various resources to make sure they are running > properly. This servlet needs to be loaded and started when the web > server (webrick) is loaded and the timer will be started when the > servlet is loaded. > > Could someone point me the right direction?I would suggest building the monitoring app outside of Rails and using drb or something similar to communicate. Keeping it inside the application could cause problems, especially if the monitoring was blocking on something. Starting at the same time isn''t hard though, just spawn a daemon process. -- Phillip Hutchings phillip.hutchings-QrR4M9swfipWk0Htik3J/w@public.gmane.org _______________________________________________ Rails mailing list Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org http://lists.rubyonrails.org/mailman/listinfo/rails
I''d rather keep things simple for now... I need rails because I do need to host web services to collect data and I need a UI... I would need to have 2 separate apps if I went with 2 processes. You said "just spawn a daemon process"... well, two things. 1) where do I start the thread? I can''t just put it in a controller, I need it to start when the web server is initialized (like configuring for load servlet in Tomcat for Java). 2) Do you mean fork the process? I''m running windows for dev, as I recall forking doesn''t work on windows? Is there any equiv to the Java "timer" in ruby? I guess I could just do an infinite loop in a separate thread and sleep after every poll. -----Original Message----- From: rails-bounces-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org [mailto:rails-bounces-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org] On Behalf Of Phillip Hutchings Sent: Tuesday, November 15, 2005 2:01 PM To: rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org Subject: Re: [Rails] Rails Servlet? On 16/11/2005, at 9:57 AM, Phil Swenson wrote:> I need functionality for the equivalent of a servlet in Java. > > Specifically, I''m writing a monitoring application. This > monitoring applicaiton will be a web service hosted in rails, as > well as a UI. but I also need to run a timer in a "servlet" that > triggers polling various resources to make sure they are running > properly. This servlet needs to be loaded and started when the web > server (webrick) is loaded and the timer will be started when the > servlet is loaded. > > Could someone point me the right direction?I would suggest building the monitoring app outside of Rails and using drb or something similar to communicate. Keeping it inside the application could cause problems, especially if the monitoring was blocking on something. Starting at the same time isn''t hard though, just spawn a daemon process. -- Phillip Hutchings phillip.hutchings-QrR4M9swfipWk0Htik3J/w@public.gmane.org
On 16/11/2005, at 10:27 AM, Phil Swenson wrote:> I''d rather keep things simple for now... I need rails because I do > need to > host web services to collect data and I need a UI... I would need > to have 2 > separate apps if I went with 2 processes.Do one for web service collection, another for anything that might block. You can still include various parts of Rails to help. Read below for why.> You said "just spawn a daemon process"... well, two things. 1) > where do I > start the thread? I can''t just put it in a controller, I need it > to start > when the web server is initialized (like configuring for load > servlet in > Tomcat for Java). 2) Do you mean fork the process? I''m running > windows for > dev, as I recall forking doesn''t work on windows?Ruby threads aren''t real threads yet - blocking inside a thread can block your entire application. Anyway, put it in environment.rb, that runs before your app loads. And no, Ruby can''t fork on Windows AFAIK, though if you install the NT UNIX layer the syscall should be available, just not from Ruby...> Is there any equiv to the Java "timer" in ruby?Have a browse of http://www.ruby-doc.org/, but I don''t recall anything.> I guess I could just do an infinite loop in a separate thread and > sleep > after every poll.It works ;) -- Phillip Hutchings phillip.hutchings-QrR4M9swfipWk0Htik3J/w@public.gmane.org _______________________________________________ Rails mailing list Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org http://lists.rubyonrails.org/mailman/listinfo/rails
On 11/15/05, Phil Swenson <phil-XITSOACK58NFw/DY4jzso32qnSAIaJbt@public.gmane.org> wrote:> > I''d rather keep things simple for now... I need rails because I do need to > host web services to collect data and I need a UI... I would need to have > 2 > separate apps if I went with 2 processes.Yes you would. You said "just spawn a daemon process"... well, two things. 1) where do I> start the thread? I can''t just put it in a controller, I need it to start > when the web server is initialized (like configuring for load servlet in > Tomcat for Java).Because of the ''shared nothing'' mentality of a rails app, it''s a bad idea to launch this from within the web app. You will end up blocking a (lighttpd | apache | webrick) process indefinitely. 2) Do you mean fork the process? I''m running windows for> dev, as I recall forking doesn''t work on windows?In *nix yes, you could check for the existance of a process and if it isn''t there, then fork. I think via a win32utils package you can do the equivalant of a fork from windows. Is there any equiv to the Java "timer" in ruby? Ruby != Rails So yes, you could easily do this in Ruby, via the use of DRb or something similar. Then in a controller in your Rails app you could poll your DRb server (for all intents this could be a little Java TCP server as well) and return the results. I guess I could just do an infinite loop in a separate thread and sleep> after every poll.See above answer about blocking web server processes. -----Original Message-----> From: rails-bounces-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org > [mailto:rails-bounces-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org] On Behalf Of Phillip > Hutchings > Sent: Tuesday, November 15, 2005 2:01 PM > To: rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org > Subject: Re: [Rails] Rails Servlet? > > > On 16/11/2005, at 9:57 AM, Phil Swenson wrote: > > > I need functionality for the equivalent of a servlet in Java. > > > > Specifically, I''m writing a monitoring application. This > > monitoring applicaiton will be a web service hosted in rails, as > > well as a UI. but I also need to run a timer in a "servlet" that > > triggers polling various resources to make sure they are running > > properly. This servlet needs to be loaded and started when the web > > server (webrick) is loaded and the timer will be started when the > > servlet is loaded. > > > > Could someone point me the right direction? > I would suggest building the monitoring app outside of Rails and > using drb or something similar to communicate. Keeping it inside the > application could cause problems, especially if the monitoring was > blocking on something. Starting at the same time isn''t hard though, > just spawn a daemon process. > > -- > Phillip Hutchings > phillip.hutchings-QrR4M9swfipWk0Htik3J/w@public.gmane.org > > > > _______________________________________________ > Rails mailing list > Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org > http://lists.rubyonrails.org/mailman/listinfo/rails >-- ===Tanner Burson==tanner.burson-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org http://tannerburson.com <---Might even work one day... _______________________________________________ Rails mailing list Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org http://lists.rubyonrails.org/mailman/listinfo/rails
On 11/15/05, Phil Swenson <phil-XITSOACK58NFw/DY4jzso32qnSAIaJbt@public.gmane.org> wrote:> Is there any equiv to the Java "timer" in ruby? > > I guess I could just do an infinite loop in a separate thread and sleep > after every poll.Why not run the script as a cron job and access your rails environment using script/running. This way every hour your cron will signal to the rails app that its time to wake up. _______________________________________________ Rails mailing list Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org http://lists.rubyonrails.org/mailman/listinfo/rails
I would highly recommend a separate Ruby script that uses DRb to communicate with the webapp. DRb is drop-dead simple, and it's also flexible: you can run the webapp and script on different hosts if you so choose, for example. You can even have this script load your Rails environment (see the Rails wiki for more) if you want to connect to the db independently or use your Rails models inside the script. I'm using this method, and it works very well. Jacob _______________________________________________ Rails mailing list Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org http://lists.rubyonrails.org/mailman/listinfo/rails
Hi, The way I would suggest you implement this is to have cron or equivelent periodically invoke methods using script/runner. For a simple opensource example I would suggest you have a look at CIA continuous integration project[1]. It will call "into" the rails application everytime a change occurs in subversion using something like; export REPOS=... export REV=... script/runner "Agent.build(\"$REPOS\", $REV)" Agent.build is a class method in app/services/agent.rb (Note that they did add app/services to ADDITIONAL_LOAD_PATH in environment.rb). A simmilar pattern could be used for your application. Every minute a cron job calls into your rails application and updates things as required. [1] http://wiki.rubyonrails.com/rails/pages/How+To+Use+CIA+For+Continuous+Integration -- Cheers, Peter Donald RealityForge.org: http://www.realityforge.org/
Thanks for all the comments... I''ll go with the suggested architecture (shared nothing)... Here''s a couple links an explanation of shared nothing: http://www.loudthinking.com/arc/000479.html http://db.cs.berkeley.edu/papers/hpts85-nothing.pdf
Onur Turgay wrote:>hi everyone, > >what does `returning` do? it is used as > >returning code =[] { >code << "something" >code << "another thing" >} > > >in what way it is different than? > >code = [] >code << "something" >code << "another thing" > > > >Yes. It is much slower ;-) And with YARV, even more so :-( I suggest to just avoid it. "returning" is derived from the K combinator of lambda calculus, where it is defined as K == \lambda x. \lambda y. x. In other words: K x y == x. The ruby version added to ActiveSupport is defined as def returning(value); yield; value; end So "returning exp block" evaluates exp, invokes block for side effects and then returns the value of exp. The "correct" definition of returning would have been def returning(value); yield(value); value; end But the code example above would then have to be written as: returning [] do |code| code << "something" code << "another thing" end Which shows that its application in this context is really a bit silly, because [] << "something" << "another thing" or even [ "something", "another thing" ] does the same thing and is much more efficient for Ruby to execute. It''s really only useful if the last statement does not return exp''s value, like in this example: returning code=[] do code << "something" code << "another thing" if condition end But adding code as last statement fixes this easily. Just my 2c.>thanks in advance > >welcome. _______________________________________________ Rails mailing list Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org http://lists.rubyonrails.org/mailman/listinfo/rails