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• SQL: empty string vs NULL value

  - by Jacek Prucia

  I know this subject is a bit controversial and there are a lot of various articles/opinions floating around the internet. Unfortunatelly, most of them assume the person doesn't know what the difference between NULL and empty string is. So they tell stories about surprising results with joins/aggregates and generally do a bit more advanced SQL lessons. By doing this, they absolutely miss the whole point and are therefore useless for me. So hopefully this question and all answers will move subject a bit forward. Let's suppose I have a table with personal information (name, birth, etc) where one of the columns is an email address with varchar type. We assume that for some reason some people might not want to provide an email address. When inserting such data (without email) into the table, there are two available choices: set cell to NULL or set it to empty string (''). Let's assume that I'm aware of all the technical implications of choosing one solution over another and I can create correct SQL queries for either scenario. The problem is even when both values differ on the technical level, they are exactly the same on logical level. After looking at NULL and '' I came to a single conclusion: I don't know email address of the guy. Also no matter how hard i tried, I was not able to sent an e-mail using either NULL or empty string, so apparently most SMTP servers out there agree with my logic. So i tend to use NULL where i don't know the value and consider empty string a bad thing. After some intense discussions with colleagues i came with two questions: am I right in assuming that using empty string for an unknown value is causing a database to "lie" about the facts? To be more precise: using SQL's idea of what is value and what is not, I might come to conclusion: we have e-mail address, just by finding out it is not null. But then later on, when trying to send e-mail I'll come to contradictory conclusion: no, we don't have e-mail address, that @!#$ Database must have been lying! Is there any logical scenario in which an empty string '' could be such a good carrier of important information (besides value and no value), which would be troublesome/inefficient to store by any other way (like additional column). I've seen many posts claiming that sometimes it's good to use empty string along with real values and NULLs, but so far haven't seen a scenario that would be logical (in terms of SQL/DB design). P.S. Some people will be tempted to answer, that it is just a matter of personal taste. I don't agree. To me it is a design decision with important consequences. So i'd like to see answers where opion about this is backed by some logical and/or technical reasons.

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• Named output parameters vs return values

  - by Abyx

  Which code is better: // C++ void handle_message(...some input parameters..., bool& wasHandled) void set_some_value(int newValue, int* oldValue = nullptr) // C# void handle_message(...some input parameters..., out bool wasHandled) void set_some_value(int newValue, out int oldValue) or bool handle_message(...some input parameters...) ///< Returns -1 if message was handled //(sorry, this documentation was broken a year ago and we're too busy to fix it) int set_some_value(T newValue) // (well, it's obvious what this function returns, so I didn't write any documentation for it) The first one doesn't have and need any documentation. It's a self-documenting code. Output value clearly says what it means, and it's really hard to make a change like this: - void handle_message(Message msg, bool& wasHandled) { - wasHandled = false; - if (...) { wasHandled = true; ... + void handle_message(Message msg, int& wasHandled) { + wasHandled = -1; + if (...) { wasHandled = ...; With return values such change could be done easily /// Return true if message was handled - bool handle_message(Message msg) { + int handle_message(Message msg) { ... - return true; + return -1; Most of compilers don't (and can't) check documentation written in comments. Programmers also tend to ignore comments while editing code. So, again, the question is: if subroutine has single output value, should it be a procedure with well-named self-documenting output parameter, or should it be a function which returns an unnamed value and have a comment describing it?

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• Graphic card for parallel programming vs traditional methods

  - by Sambatyon

  With a simple search in amazon one can see that the modern approach for parallel programming is to use your graphic card. However I am still a little bit skeptical about it. My last computer has an 8 core CPU which I need is enough for basic all my parallel needs, if I need more I will probably use MPI through a network using my old machines. All in all, Why and/or when should I use CUDA or another method which uses my graphic card instead of traditional methods like pthreads, java threads, boost threads or the new C++ 11 threads? What about using processes?

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• Sanity checks vs file sizes

  - by Richard Fabian

  In your game assets do you make room for explicit sanity checks, or do you have some generally expected bounds which you assert? I've been thinking about how we compress data and thought that it's much better to have the former, and less of the latter. If your data can exceed your normal valid ranges, but if it does it's an error, then surely that implies you're not compressing the data well enough? What do you do to find out if your data is compressed as far as it can be, and what do you use to ensure your data isn't corrupted and ensure it's an official release? EDIT I'm not interested in sanity checking the file size, but instead, how you manage your sanity checks and whether you arrange the excess size caused by the opportunity to do sanity checks by using explicit extra data, or through allowing the data enough file space (data member size) to be out of valid range and thus able to be checked merely by looking at the asset in memory after loading.

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• PC Building: Intel's Turbo Boost vs AMD's Turbo Core

  <b>PC Business: </b>"Even now there are few applications that take full advantage of multicore processers. For those that do the benefits are huge, but some applications just don't work well in a multithreaded environment."

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• Boss solution vs Developer solution

  - by mahen23

  The problem: When we were sending newsletters to customers, there was no way to confirm if the customer already received the mail. So the boss decided to implement this idea: Boss's Idea: Each time mail was being sent, do an INSERT in a db with the title of the newsletter being sent and the email address which is receving the email address. To ensure that any email address does not receive the same email twice, do a SELECT in the table and find the title of the newsletter being sent: if (title of newsletter is found) { check to see of the email we are sending mail to is already present. if it does, do not send mail } else { send mail } MY idea: create a column called unique and mark it as UNIQUE. Each time mail was being sent, concatenate email + newsletter id and record it in the UNIQUE row. The next time we do a "mysql_affected_rows" check to see if our INSERT was successful, we send the mail, else, there is already a duplicate and no need to send it.

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• Manual Submission Vs Automated Submission

  Directory submission involves submitting a website to web directories. There are many types of directories including niche directory, general directory, and regional directory. Submitting your website to directory can help to increase the exposure of the website.

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• Tech Comics: "Social Networking vs. Life"

  <b>Tech Comics:</b> "Social networking activities like Facebook and Twitter consumer so much attention that it may be hard to find a balance with life itself."

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• Tender vs. Requirements vs. Solution Design

  - by Tom Tom

  Conventionally, which of the above documents is deemed to hold the most weight when it comes to system acceptance? I recently had a conversation along these lines: It was argued that the initial requirements / tender documentation should be used to determine system acceptance. It was said that the solution design only serves to describe the way in which the system will solve the problem, not the problem it will solve. Furthermore, it was argued that if requirements are missed during solution design, the requirements should be referenced during system acceptance and that if any requirements were missed then the original tender should be referenced. Conversely, I suggested that - while requirements may be based on the original tender - they supersede it once agreed with the stakeholders. Furthermore, during solution design, analysis is performed to address and refine these initial requirements, translating them into a system capable of meeting the actual requirements. Once signed off by the relevant users, this solution design should absolutely represent the requirements (by virtue of the fact that it's designed upon them) but actually supersedes them as the basis for system acceptance. Is one of the above arguments more valid than the other?

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• IOS Variable vs Property

  - by William Smith

  Just started diving into Objective-C and IOS development and was wondering when and the correct location I should be declaring variables/properties. The main piece of code i need explaining is below: Why and when should i be declaring variables inside the interface statement and why do they have the same variable with _ and then the same one as a property. And then in the implementation they do @synthesize tableView = _tableView (I understand what synthesize does) Thanks :-) @interface ViewController : UIViewController <UITableViewDataSource, UITableViewDelegate> { UITableView *_tableView; UIActivityIndicatorView *_activityIndicatorView; NSArray *_movies; } @property (nonatomic, retain) UITableView *tableView; @property (nonatomic, retain) UIActivityIndicatorView *activityIndicatorView; @property (nonatomic, retain) NSArray *movies;

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• Part 6: Extensions vs. Modifications

  - by volker.eckardt(at)oracle.com

  Customizations = Extensions + Modifications In the EBS terminology, a customization can be an extension or a modification. Extension means that you mainly create your own code from scratch. You may utilize existing views, packages and java classes, but your code is unique. Modifications are quite different, because here you take existing code and change or enhance certain areas to achieve a slightly different behavior. Important is that it doesn't matter if you place your code at the same or at another place – it is a modification. It is also not relevant if you leave the original code enabled or not! Why? Here is the answer: In case the original code piece you have taken as your base will get patched, you need to copy the source again and apply all your changes once more. If you don't do that, you may get different results or write different data compared to the standard – this causes a high risk! Here are some guidelines how to reduce the risk: Invest a bit longer when searching for objects to select data from. Rather choose a view than a table. In case Oracle development changes the underlying tables, the view will be more stable and is therefore a better choice. Choose rather public APIs over internal APIs. Same background as before: although internal structure might change, the public API is more stable. Use personalization and substitution rather than modification. Spend more time to check if the requirement can be covered with such techniques. Build a project code library, avoid that colleagues creating similar functionality multiple times. Otherwise you have to review lots of similar code to determine the need for correction. Use the technique of “flagged files”. Flagged files is a way to mark a standard deployment file. If you run the patch analyse (within Application Manager), the analyse result will list flagged standard files in case they will be patched. If you maintain a cross reference to your own CEMLIs, you can easily determine which CEMLIs have to be reviewed. Implement a code review process. This can be done by utilizing team internal or external persons. If you implement such a team internal process, your team members will come up with suggestions how to improve the code quality by themselves. Review heavy customizations regularly, to identify options to reduce complexity; let's say perform this every 6th month. You may not spend days for such a review, but a high level cross check if the customization can be reduced is suggested. De-install customizations which are no more required. Define a process for this. Add a section into the technical documentation how to uninstall and what are possible implications. Maintain a cross reference between CEMLIs and between CEMLIs, EBS modules and business processes. Keep this list up to date! Share this list! By following these guidelines, you are able to improve product stability. Although we might not be able to avoid modifications completely, we can give a much better advise to developers and to our test team. Summary: Extensions and Modifications have to be handled differently during their lifecycle. Modifications implicate a much higher risk and should therefore be reviewed more frequently. Good cross references allow you to give clear advise for the testing activities.

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• Using C++, how to call a base class method from a derived class method and apply this to an object passed as an argument?

  - by Chris

  I can't figure out how to call a base class method from a derived class method but concurrently applying this method call at an object passed as argument. What I mean is this: class Animal { virtual void eat(Animal& to_be_eaten) = 0; }; class Carnivores: public Animal { virtual void eat(Animal& to_be_eaten) { /*implementation here*/} }; class Wolf : public Carnivores { virtual void eat(Animal& to_be_eaten) { /*call eat method(of Base class) of Base to_be_eaten here*/ } } I thought of something like this dynamic_cast<Carnivores&>(to_be_eaten).eat(*this) //and got a segmentation fault Is there any way for this to be done? Thank you! New edit:: Updated the code

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• how to get individual(s) for given class/individual with given object property using SPARQL

  - by udayalkonline

  hi, I have simple ontology called "campus.owl".There is a class called"Lecturer" and which has two sub classes ,RegularLecturer and VisitingLecturer.There is a another class called "Student" which is a sibling class of Lecturer class. I have created individuals for all the classes. Student class is joind with Lecture class with "has" object property. problem I want to get some Lecturer/VisitingLecturer individuals for given student individual. Could you please help me to get this result! Thanks in advance! PREFIX rdfs: http://www.w3.org/2000/01/rdf-schema# PREFIX rdf: http://www.w3.org/1999/02/22-rdf-syntax-ns# PREFIX my: http://www.semanticweb.org/ontologies/2010/5/Ontology1275975684120.owl# SELECT ?lec WHERE { ?lec..........??? } any idea..?? Thank in advance!

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• Canada vs Norway

  - by guybarrette

  During the winter Olympics, I had a little bet with Sondre Bjellås.  Sondre is the RD for Olso, Norway, a rising rock star in the .NET world and a very great guy.  The bet was that if Canada would win Gold against Norway in the man curling final, I would wear something funny and Norwegian like a Viking hat at Mix while Sondre would wear a Canadian jersey. Well, guess who won? You know what?  I glad that Norway didn’t win because I fear I would have had to wear the famous Norwegian curling pants! var addthis_pub="guybarrette";

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• '/'var/www/' vs '/home/$USER/public_html'

  - by OrganizedFellow

  I recently started using Ubuntu as a LAMP server. I've come across plenty of tutorials that say to place the files at '/var/www/' and I've also seen others that put them in '/home/$USER/public_html/'. During my testing and figuring stuff out, I was successfully able to view a test site URL from each location. Is one better than the other? I thought that maybe it was just preference. But the more I think about it, the more I want to keep all my work in my Home folder.

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• referencing ints from other classes

  - by user357032

  if i wanted to reference an int from another class how would i go about doing that??? public class Zoom extends View { private Drawable image; public int zoomControler=20; public Zoom(Context context) { super(context); image=context.getResources().getDrawable(R.drawable.icon); setFocusable(true); } @Override protected void onDraw(Canvas canvas) { // TODO Auto-generated method stub super.onDraw(canvas); image.setBounds((getWidth()/2)-zoomControler, (getHeight()/2)-zoomControler, (getWidth()/2)+zoomControler, (getHeight()/2)+zoomControler); image.draw(canvas); } } class HelloOnTouchListener implements OnTouchListener{ @Override public boolean onTouch(View arg0, MotionEvent arg1) { return true; } } in this case i want to reference the zoomControler from the first class in the second helloontouchlistener class

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• Pointers in C vs No pointers in PHP

  - by AnnaBanana

  Both languages have the same syntax. Why does C have the weird * character that denotes pointers (which is some kind of memory address of the variable contents?), when PHP doesn't have it and you can do pretty much the same things in PHP that you can do in C, without pointers? I guess the PHP compiler handles this internally, why doesn't C do the same? Doesn't this add unneeded complexity in C? For example I don't understand them :)

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• API Class with intensive network requests

  - by Marco Acierno

  I'm working an API which works as "intermediary" between a REST API and the developer. In this way, when the programmer do something like this: User user = client.getUser(nickname); it will execute a network request to download from the service the data about the user and then the programmer can use the data by doing things like user.getLocation(); user.getDisplayName(); and so on. Now there are some methods like getFollowers() which execute another network request and i could do it in two ways: Download all the data in the getUser method (and not only the most important) but in this way the request time could be very long since it should execute the request to various urls Download the data when the user calls the method, it looks like the best way and to improve it i could cache the result so the next call to getFollowers returns immediately with the data already download instead of execute again the request. What is the best way? And i should let methods like getUser and getFollowers stop the code execution until the data is ready or i should implement a callback so when the data is ready the callback gets fired? (this looks like Javascript)

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• Self-documenting code vs Javadocs?

  - by Andiaz

  Recently I've been working on refactoring parts of the code base I'm currently dealing with - not only to understand it better myself, but also to make it easier for others who are working on the code. I tend to lean on the side of thinking that self-documenting code is nice. I just think it's cleaner and if the code speaks for itself, well... That's great. On the other hand we have documentation such as javadocs. I like this as well, but there's a certain risk that comments here gets outdated (as well as comments in general of course). However, if they are up-to-date they can be extremely useful of say, understanding a complex algorithm. What are the best practices for this? Where do you draw the line between self-documenting code and javadocs?

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• Country specific content vs global content

  - by Ando

  I have a global product presentation website myproduct.com For certain countries I also own the country domain: myproduct.co.uk, myproduct.com.au, myproduct.es, myproduct.de, etc. The presentation website is translated in multiple languages and I set up redirects: myproduct.es will redirect to myproduct.com/es/, myproduct.de will redirect to myproduct.com/de/, etc. . The content so far is the same, just translated in different languages. The advantages are that it's easy to keep the content aligned - everything is managed from one centralized dashboard (I'm using Wordpress with qtranslate). Now I'm running into trouble as for different countries I want localized content - for UK I want to run different promotions and use a different reseller than for .com.au so I would like that users coming from myproduct.co.uk see something different than those coming from myproduct.com.au (and not be redirected to myproduct.com as they are right now). How can I achieve this? I could duplicate the whole main website and modify only certain parts but then I would have a lot of duplicate content (e.g. info about how the product works) and I would have pages that are likely to change (FAQ page) that I would have to keep updated over all websites. I can duplicate only partially the main website: on the localized website I would have only the pages that are different and then all other links would point to the .com site. This would solve the duplication problem but would cause confusion for the user as you would navigate from .co.uk to .com without noticing and then wonder how to get back. Other, better option?

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• 2D Animation Smoothness - Delta time vs. Kinematics

  - by viperld002

  I'm animating a sprite in 2D with key frames of rotation and xy-positions. I've recently had a discussion with someone saying that when the device (happens to be an iPad using cocos2D) hits a performance bump due to whatever else the user may be doing, lag will arise and that the best way to fight it is to not use actual positions, but velocities, accelerations and torques with kinematics. His message is to evaluate the positions and rotations from these speeds at the current point in time. I've never experienced a situation where I've heard of using kinematics to stem lag in 2D animations and am not sure of how effective it could be. Also, it seems to be overkill. The application is not networked so it's all running on a local device. The desired effect is that the animation always plays as closely as it can to the target frame rate. Wouldn't the technique suffer the same problems as just using the time since the last frame or a fixed time step since the kinematics would also require some time value to perform the calculation? What techniques could you suggest to best achieve the desired effect? EDIT 1 Thank you for your responses, they are very illuminating. I want to clarify my question before choosing an answer however, to make sure that this post really serves it's purpose. I have a sprite of a ball, and a text file with 3 arrays worth of information (rotation,translations x, translations y) with each unit of information existing as a key frame to be stepped through (0 to 49 and back to 0 to replay it again). I have this playing by interpolating from the current key frame to the next, every n-units of time. The animation is visibly correct when compared to a video I was given of it, and it is smooth because of the interpolations between the key frames. This is the existing state of the project. There are no physics simulated, only a static animation of a ball moving in a way an artist specifically designed. Should I, instead of rotation in degrees and translations by positions in space, derive velocities, accelerations and torques to express this static animation as a function of time? As in, position now = foo(time now), where foo uses kinematics.

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• google analytics - real-time user stats vs audience overview user stats

  - by udog

  When looking at the real-time analytics reporting for our app, it shows around 150-180 users, say around 10AM (our peak usage time). When I look at the Audience Overview report for the same day (hourly breakdown), the number of users shown for the 10AM hour is over 1000. I'm sure this has to do with some sort of aggregation, but I would like to know more about how these two numbers are calculated in order to understand it.

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• Would like some help in understanding rendering geometry vs textures

  - by Anon

  So I was just pondering whether it is more taxing on the GPU to render geometry or a texture. What I'm trying to see is whether there is a huge difference in rendering two scenes with the same setup: Scene 1: Example Object: A dirt road (nothing else) Geometry: Detailed road, with all the bumps, cracks and so forth done in the mesh Scene 2: Example Object: A dirt road (nothing else) Geometry: A simple mesh, in a form of a road, but in this case maps and textures are simulating cracks, bumps, etc... So of these two, which one is likely to tax the hardware more? Or is it not a like for like comparison? What would be the best way of doing something like this? Go heavy on the textures? Or have a blend of both?

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• Helper class to dynamically modify the Location configuration element

  - by anas

  The location element is used to restrict user or role access on a specific path.The path could be a folder,aspx page,ashx,axd or any other file that is handled by ASP.NET runtime. In most cases, you use that element declarativley in the web.config file of your website.In this case, you are declaratively telling the ASP.NET runtime and specifically the UrlAuthorizationModule or the FileAuthorizationModule (depending on the Authentication Mode) to grant/deny the access to that path for the specified...(read more)

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• Referring EDMX file in Separate VS Project from T4 Template

  - by Paul Petrov

  In my project I needed to separate template generated entities, context in separate projects from the EDMX file. I’ve stumbled across this problem how to make template generator to find edmx file without hardcoding absolute path into the template. Using relative path directly (inputFile=@”..\ProjectFolder\DataModel.edmx”) generated error: Error      2              Running transformation: System.IO.DirectoryNotFoundException: Could not find a part of the path 'C:\Program Files (x86)\Microsoft Visual Studio 10.0\Common7\ProjectFolder\DataModel.edmx' The code that worked well for me when placed in the beginning of the .tt file: … string rootPath = Host.ResolvePath(String.Empty); string relativePath = @"..\\ProjectDir\\DataModel.edmx"; string inputFile = Path.Combine(rootPath, relativePath); EdmItemCollection ItemCollection = loader.CreateEdmItemCollection(inputFile); …

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