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  • c++ try catch practices

    - by Tony
    Is this considered good programming practise in C++: try { // some code } catch(someException) { // do something } catch (...) { // left empty <-- Good Practise??? }

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  • Trying to understand the usage of class_eval

    - by eMxyzptlk
    Hello everyone, I'm using the rails-settings gem, and I'm trying to understand how you add functions to ActiveRecord classes (I'm building my own library for card games), and I noticed that this gem uses one of the Meta-programming techniques to add the function to the ActiveRecord::Base class (I'm far from Meta-programming master in ruby, but I'm trying to learn it) module RailsSettings class Railtie < Rails::Railtie initializer 'rails_settings.initialize', :after => :after_initialize do Railtie.extend_active_record end end class Railtie def self.extend_active_record ActiveRecord::Base.class_eval do def self.has_settings class_eval do def settings RailsSettings::ScopedSettings.for_thing(self) end scope :with_settings, :joins => "JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}')", :select => "DISTINCT #{self.table_name}.*" scope :with_settings_for, lambda { |var| { :joins => "JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}') AND settings.var = '#{var}'" } } scope :without_settings, :joins => "LEFT JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}')", :conditions => 'settings.id IS NULL' scope :without_settings_for, lambda { |var| { :joins => "LEFT JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}') AND settings.var = '#{var}'", :conditions => 'settings.id IS NULL' } } end end end end end end What I don't understand is why he uses class_eval on ActiveRecord::Base, wasn't it easier if he just open the ActiveRecord::Base class and define the functions? Specially that there's nothing dynamic in the block (What I mean by dynamic is when you do class_eval or instance_eval on a string containing variables) something like this: module ActiveRecord class Base def self.has_settings class_eval do def settings RailsSettings::ScopedSettings.for_thing(self) end scope :with_settings, :joins => "JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}')", :select => "DISTINCT #{self.table_name}.*" scope :with_settings_for, lambda { |var| { :joins => "JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}') AND settings.var = '#{var}'" } } scope :without_settings, :joins => "LEFT JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}')", :conditions => 'settings.id IS NULL' scope :without_settings_for, lambda { |var| { :joins => "LEFT JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}') AND settings.var = '#{var}'", :conditions => 'settings.id IS NULL' } } end end end end I understand the second class_eval (before the def settings) is to define functions on the fly on every class that 'has_settings' right ? Same question here, I think he could use "def self.settings" instead of "class_eval.... def settings", no ?

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  • should we use a captcha for Sign Up ?

    - by fabrice
    Hello, I know it's not really a programming question but I don't know where to ask it. Should i use a captcha in my sign up form ? Facebook, twitter, foursquare, gowalla etc... don't use one (or not a visible one). Is there an invisible catpcha on theses sites ? Thank you

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  • Articles about replication schemes/algorithms?

    - by jkff
    I'm designing an hierarchical distributed system (every node has zero or more "master" nodes to which it propagates its current data). The data gets continuously updated and I'd like to guarantee that at least N nodes have almost-current data at any given time. I do not need complete consistency, only eventual consistency (t.i. for any time instant, the current snapshot of data should eventually appear on at least N nodes. It is tricky to define the term "current" here, but still). Nodes may fail and go back up at any moment, and there is no single "central" node. O overflowers! Point me to some good papers describing replication schemes. I've so far found one: Consistency Management in Optimistic Replication Algorithms

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  • How to replace empty string with zero in comma-separated string?

    - by dsaccount1
    "8,5,,1,4,7,,,,7,,1,9,3,6,,,8,6,3,9,,2,5,4,,,,,3,2,,,7,4,1,1,,4,,6,9,,5,,,,5,,,1,,6,3,,,6,5,,,,7,4,,1,7,6,,,,8,,5,,,7,1,,3,9," I'm doing a programming challenge where i need to parse this sequence into my sudoku script. Need to get the above sequence into 8,5,0,1,4,7,0,0,0,7,0,1,9,3,6,0,0,8......... I tried re but without success, help is appreciated, thanks.

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  • What is the best way to password protect folder/page using php without a db or username

    - by Salt Packets
    What is the best way to password protect folder using php without a database or user name but using. Basically I have a page that will list contacts for organization and need to password protect that folder without having account for every user . Just one password that gets changes every so often and distributed to the group. I understand that it is not very secure but never the less I would like to know how to do this. In the best way. It would be nice if the password is remembered for a while once user entered it correctly.

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  • Building a minimal plugin architecture in Python.

    - by dF
    I have an application, written in Python, which is used by a fairly technical audience (scientists). I'm looking for a good way to make the application extensible by the users, i.e. a scripting/plugin architecture. I am looking for something extremely lightweight. Most scripts, or plugins, are not going to be developed and distributed by a third-party and installed, but are going to be something whipped up by a user in a few minutes to automate a repeating task, add support for a file format, etc. So plugins should have the absolute minimum boilerplate code, and require no 'installation' other than copying to a folder (so something like setuptools entry points, or the Zope plugin architecture seems like too much.) Are there any systems like this already out there, or any projects that implement a similar scheme that I should look at for ideas / inspiration?

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  • how to build good python web application

    - by Moayyad Yaghi
    hello i never worked with web programming and i've been asked lately to write a web-based software to manage assets and tasks. to be used by more than 900 persons what are the recommended modules , frameworks , libraries for this task. and it will be highly appreciated if you guyz recommend some books and articles that might help me. thanks in advance

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  • PHP click event handlers.

    - by Guru
    Hello, I'm new to PHP programming and I wanted to know that is it possible to handle PHP events as we do in ASP.NET I mean I've got a img and I want to perform some task on click event of this img. I know how to do it in ASP.NET but please help me in context of PHP Thanks, GURU

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  • Are there any good books to learn C++ if you already know Java and C#

    - by JF LR
    Hi, I would like to know if you have any good books that teach C++ programming without repeating basic stuff. In fact, I already well know Java and C#. I also have a basic knowledge in C and assembly, so I understand a little bit pointer arithmetic, manual memory management and heap based allocation. I was looking at O'Reilly's C++ in a Nutshell and was also wondering if this book would be a good choice. Thank you

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  • Removing the transperancy from image while keeping the actual image

    - by KPL
    Hello people, I have three images,and , they are not square or rectangular in shape. They are just like face of anyone. So,basically, my images are in the size 196x196 or anything like that, but complete square or rectangle with the face in the middle and transperant background in the rest of the portion. Now, I want to remove the transperant background too and just keep the faces. Don't know if this is possible and mind you, this isn't a programming question.

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  • AOP support in Delphi

    - by Miel
    Hi, Is it possible to do Aspect Oriented Programming in Delphi? I would be interested in native support as well as third party solutions. I don't have a specific problem I want to solve with AOP, but am simply interested in studying AOP. Thanks, Miel Bronneberg.

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  • FileInputStream for a generic file System

    - by Akhil
    I have a file that contains java serialized objects like "Vector". I have stored this file over Hadoop Distributed File System(HDFS). Now I intend to read this file (using method readObject) in one of the map task. I suppose FileInputStream in = new FileInputStream("hdfs/path/to/file"); wont' work as the file is stored over HDFS. So I thought of using org.apache.hadoop.fs.FileSystem class. But Unfortunately it does not have any method that returns FileInputStream. All it has is a method that returns FSDataInputStream but I want a inputstream that can read serialized java objects like vector from a file rather than just primitive data types that FSDataInputStream would do. Please help!

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  • continuous integration web service

    - by Josh Moore
    I am in a position where I could become a team leader of a team distributed over two countries. This team would be the tech. team for a start up company that we plan to bootstrap on limited funds. So I am trying to find out ways to minimize upfront expenses. Right now we are planning to use Java and will have a lot of junit tests. I am planing on using github for VCS and lighthouse for a bug tracker. In addition I want to add a continuous integration server but I do not know of any continuous integration servers that are offered as a web service. Does anybody know if there are continuous integration servers available in a software as a service model? P.S. if anybody knows were I can get these three services at one location that would be great to know to.

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  • Switch case assembly level code

    - by puffadder
    Hi All, I am programming C on cygwin windows. After having done a bit of C programming and getting comfortable with the language, I wanted to look under the hood and see what the compiler is doing for the code that I write. So I wrote down a code block containing switch case statements and converted them into assembly using: gcc -S foo.c Here is the C source: switch(i) { case 1: { printf("Case 1\n"); break; } case 2: { printf("Case 2\n"); break; } case 3: { printf("Case 3\n"); break; } case 4: { printf("Case 4\n"); break; } case 5: { printf("Case 5\n"); break; } case 6: { printf("Case 6\n"); break; } case 7: { printf("Case 7\n"); break; } case 8: { printf("Case 8\n"); break; } case 9: { printf("Case 9\n"); break; } case 10: { printf("Case 10\n"); break; } default: { printf("Nothing\n"); break; } } Now the resultant assembly for the same is: movl $5, -4(%ebp) cmpl $10, -4(%ebp) ja L13 movl -4(%ebp), %eax sall $2, %eax movl L14(%eax), %eax jmp *%eax .section .rdata,"dr" .align 4 L14: .long L13 .long L3 .long L4 .long L5 .long L6 .long L7 .long L8 .long L9 .long L10 .long L11 .long L12 .text L3: movl $LC0, (%esp) call _printf jmp L2 L4: movl $LC1, (%esp) call _printf jmp L2 L5: movl $LC2, (%esp) call _printf jmp L2 L6: movl $LC3, (%esp) call _printf jmp L2 L7: movl $LC4, (%esp) call _printf jmp L2 L8: movl $LC5, (%esp) call _printf jmp L2 L9: movl $LC6, (%esp) call _printf jmp L2 L10: movl $LC7, (%esp) call _printf jmp L2 L11: movl $LC8, (%esp) call _printf jmp L2 L12: movl $LC9, (%esp) call _printf jmp L2 L13: movl $LC10, (%esp) call _printf L2: Now, in the assembly, the code is first checking the last case (i.e. case 10) first. This is very strange. And then it is copying 'i' into 'eax' and doing things that are beyond me. I have heard that the compiler implements some jump table for switch..case. Is it what this code is doing? Or what is it doing and why? Because in case of less number of cases, the code is pretty similar to that generated for if...else ladder, but when number of cases increases, this unusual-looking implementation is seen. Thanks in advance.

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  • List of private iPhone APIs?

    - by diego nunes
    . . Hi there, everybody. . . I need to do an app to be distributed ad hoc (it doesn't need to go to the store) but I need to get the information about the "data usage" (gprs/3g traffic). It is available on the system, but there is no official API call to get that info. One app made it through Apple testing (it's called "Download Meter"), though, and I emailed the guys to see if they would share the call, but they were not in that mood. . . Is there any list of private APIs or anything like that? Does anyone have any ideas of how could I get that info? Again: the app doesn't need to go to the store, but I need to install it on stock iPhone (ad hoc will do). . Thanks.

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  • How does UITableViewController knows its dataSource and delegate

    - by denniss
    I am following the BigNerdRanch iOS Programming book and I am on this one chapter that deals with UITableViewController. I have been wondering however where UITableViewController finds out about its delegate and dataSource. Currently I have it as @interface ItemsViewController : UITableViewController <UITableViewDataSource, UITableViewDelegate> But there is nothing that looks like: [self.tableView setDelegate:self] I am just wondering how the UITableViewController finds out about its delegate and dataSource

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