Lazy evaluation in Ruby

Posted by fifigyuri on Stack Overflow See other posts from Stack Overflow or by fifigyuri
Published on 2010-03-17T10:26:36Z Indexed on 2010/03/17 10:31 UTC
Read the original article Hit count: 358

Filed under:

ruby

|

lazy-loading

I have a situation for Ruby, where an object is possibly necessary to be created, but it is not sure. And as the creation of the object might be costly I am not too eager creating it. I think this is a clear case for lazy loading. How can I define an object which is not created only when someone sends a message to it? The object would be created in a block. Is there a way for simple lazy loading/initialisation in Ruby? Are these things supported by some gems, which provide different solutions for various cases of lazy initialisation of objects? Thanks for your suggestions!

© Stack Overflow or respective owner

Related posts about ruby

Setting up Rails to work with sqlserver

as seen on Stack Overflow - Search for 'Stack Overflow'
Ok I followed the steps for setting up ruby and rails on my Vista machine and I am having a problem connecting to the database. Contents of database.yml development: adapter: sqlserver database: APPS_SETUP Host: WindowsVT06\SQLEXPRESS Username: se Password: paswd Run rake db:migrate… >>> More
marshal data too short!!!

as seen on Stack Overflow - Search for 'Stack Overflow'
My application requires to keep large data objects in session. There are like 3-4 data objects each created by parsing a csv containing 150 X 20 cells having strings of 3-4 characters. My application shows this error- "marshal data too short". I tried this- Deleting the old session table. Deleting… >>> More
Sinatra and XML POST request

as seen on Stack Overflow - Search for 'Stack Overflow'
I don't know is it my mistake or no. So i have that code: <code> post '/singin/get_token' do content_type :xml puts request.body.read puts xmlRequest xmlRequest = REXML::Document.new(request.body.read) ... </code> And when i post something like that: <code> <?xml… >>> More
how to change ruby path from /usr/bin/ruby to /usr/local/bin/ruby

as seen on Stack Overflow - Search for 'Stack Overflow'
reading around the various ruby install tutorials it's required to change path from /usr/bin/ruby to /usr/local/bin/ruby but i cant seem to be able to do it. Ultimately i want to install Ruby 1.9.2, should i uninstall 1.8.7 or what? i tried to install Ruby 1.9.2 with macports, the installation seemed… >>> More
strange bundler error: tar_input.rb:49:in `initialize': not in gzip format (Zlib::GzipFile::Error) o

as seen on Stack Overflow - Search for 'Stack Overflow'
i am getting a strange bundler error when running bundle pack with bundler 0.9.12 any ideas? (see pastie for a better formatted code: http://pastie.org/881328 ) /opt/ruby-enterprise-1.8.7-2010.01/lib/ruby/site_ruby/1.8/rubygems/package/tar_input.rb:49:in `initialize': not in gzip format (Zlib::GzipFile::Error) … >>> More

Related posts about lazy-loading

Implicit Lazy Loading vs Explicit Lazy Loading

as seen on Stack Overflow - Search for 'Stack Overflow'
I've been reading Entity Framework and people were crying over why there was not implicit lazy loading or something. Basically I've been searching things about Lazy Loading and now I know what it is : It is a design pattern which allows us to load objects when they are really needed. But what is… >>> More
Android ListView Data Virtualization - Lazy Loading more than 10,000 items

as seen on Stack Overflow - Search for 'Stack Overflow'
Does anybody have an example of lazy loading (about 10,000 items) an Android ListView from a Sqlite databse? >>> More
Lazy loading of Blob properties of one class

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, My class contains "summary" and "title" properties those are Blob and other properties. Code:(I write some part of class) public class News extends BaseEntity{ @Lob @Basic(fetch = FetchType.LAZY) public String getSummary() { return summary; } @Lob @Basic(fetch = FetchType… >>> More
Lazy Loading Association and Casting

as seen on Stack Overflow - Search for 'Stack Overflow'
I am using NHibernate 2.0.1 and .NET I am facing issues with Lazy loading an association I have a BusinessObject class that has associations to other BusinessObject in it, and it can go deeper. The following function is in the BusinessObject to read the values of a collection in the BusinessObject… >>> More
Entity Framework 4, WCF & Lazy Loading Tip

as seen on Geeks with Blogs - Search for 'Geeks with Blogs'
If you are doing any work with Entity Framework and custom WCF services in EFv1, everything works great. As soon as you jump to EFv4, you may find yourself getting odd errors that you can’t seem to catch. The problem is almost always has something to do with the new lazy loading feature in Entity… >>> More