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• Does a "nofollow" attribute on a link prevent URL discovery by search engines?

  - by Stephen Ostermiller

  I know that nofollow prevents link juice from being passed across a link. But if search engine robots discover a link with a nofollow on it, will they add that link to their crawl queue? In other words, if I create a link to a brand new page and put a rel=nofollow attribute on that link, will it prevent search engine bots (particularly Googlebot) from crawling the page. (Assuming that this link remains the only link into that page.) I've read conflicting reports about this over the years and I'm looking for authoritative references about the current state of affairs. Official statements from Google or published results of independent testing would be ideal.

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• Object-Oriented equivalent of LISP's progn function?

  - by Archer

  I'm currently writing a LISP parser that iterates through some AutoLISP code and does its best to make it a little easier to read (changing prefix notation to infix notation, changing setq assignments to "=" assignments, etc.) for those that aren't used to LISP code/only learned object oriented programming. While writing commands that LISP uses to add to a "library" of LISP commands, I came across the LISP command "progn". The only problem is that it looks like progn is simply executing code in a specific order and sometimes (not usually) assigning the last value to a variable. Am I incorrect in assuming that for translating progn to object-oriented understanding that I can simply forgo the progn function and print the statements that it contains? If not, what would be a good equivalent for progn in an object-oriented language?

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• Checking is sides of cubes are solid

  - by Christian Frantz

  In relation to this question: http://gamedev.stackexchange.com/a/28524/31664 And a question I asked earlier: Creating a DrawableGameComponent And also because my internet is too slow to get on chat. I'm wondering how to check if the sides of a cube are solid. I've created 12 methods, each one creating indices and vertices for sides of a cube. Now when I use these methods, the cube creates how it should. All 6 sides show up and its like I didnt change a thing. How can use if statements to check if the side of a cube is solid? The pseudocode from the question above shows this: if(!isSolidAt(x+1,y,z)) verticesToDraw += AddXPlusFace(x,y,z) But in my case is would be: if(!sideIsSolid) SetUpFrontFaceIndices(); My method simply takes these index and vertex values and adds them to a list indicesToDraw and verticesToDraw, as shown in the answer above

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• Is true multithreading really necessary?

  - by Jonathan Graef

  So yeah, I'm creating a programming language. And the language allows multiple threads. But, all threads are synchronized with a global interpreter lock, which means only one thread is allowed to execute at a time. The only way to get the threads to switch off is to explicitly tell the current thread to wait, which allows another thread to execute. Parallel processing is of course possible by spawning multiple processes, but the variables and objects in one process cannot be accessed from another. However the language does have a fairly efficient IPC interface for communicating between processes. My question is: Would there ever be a reason to have multiple, unsynchronized threads within a single process (thus circumventing the GIL)? Why not just put thread.wait() statements in key positions in the program logic (presuming thread.wait() isn't a CPU hog, of course)? I understand that certain other languages that use a GIL have processor scheduling issues (cough Python), but they have all been resolved.

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• Why does F. Wagner consider "NOT (AI_LARGER_THAN_8.1)" to be ambiguous?

  - by oosterwal

  In his article on Virtual Environments (a part of his VFSM specification method) Ferdinand Wagner describes some new ways of thinking about Boolean Algebra as a software design tool. On page 4 of this PDF article, when describing operators in his system he says this: Control statements need Boolean values. Hence, the names must be used to produce Boolean results. To achieve this we want to combine them together using Boolean operators. There is nothing wrong with usage of AND and OR operators with their Boolean meaning. For instance, we may write: DI_ON OR AI_LARGER_THAN_8.1 AND TIMER_OVER to express the control situation: digital input is on or analog input is larger than 8.1 and timer is over. We cannot use the NOT operator, because the result of the Boolean negation makes sense only for true Boolean values. The result of, for instance, NOT (AI_LARGER_THAN_8.1) would be ambiguous. If "AI_LARGER_THAN_8.1" is acceptable, why would he consider "NOT (AI_LARGER_THAN_8.1)" to be ambiguous?

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• Difference between spring setter and interface injection?

  - by Satish Pandey

  I know how constructor and setter injection works in spring. Normally I use interfaces instead of classes to inject beans using setter and I consider it as interface injection, but in case of constructor we also use interfaces (I am confused). In following example I use JobProcessor interface instead of JobProcessorImpl class. public class JobScheduler { // JobProcessor interface private JobProcessor jobProcessor; // Dependecy injection public void setJobProcessor(JobProcessor jobProcessor){ this.jobProcessor = jobProcessor; } } I tried to find a solution by googling but there are different opinions by writers. Even some people says that spring doesn't support interface injection in their blogs/statements. Can someone help me by example?

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• Ambiguous Comparison Hint

  - by Ondrej Brejla

  Hi everybody! Today we would like to show you some new hint which will be available in NetBeans 7.3. It's called Ambiguous Comparison hint. Its name seems to be quite fuzzy, but it describes exactly what the hint does. It tries to check all comparisons whether they are intended. Because sometimes you want to make a simple assignment, but you make a typo and comparison appears. It's really dangerous mistake because then your code doesn't work as expected. Your application can produce buggy results. So here is how it looks like: But sometimes a comparison is really intended. E.g. in return statements when you want to return a boolean, so then the hint works as expected and no warning appears. That's all for today and as usual, please test it and if you find something strange, don't hesitate to file a new issue (component php, subcomponent Editor). Thanks.

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• Using Substring() in XML FLOWR Queries

  - by Jonathan Kehayias

  Tonight I was monitoring the #sqlhelp hashtag on Twitter for a response to a question I asked when Randy Knight ( Twitter ) asked a question about using SUBSTRING in FLOWR statements with XML. #sqlhelp Is there a way to do a SQL Type "LIKE" or "SUBSTRING" in the where clause of FLWOR statement? Need to evaluate just first n chars. By the time I posted a response, Randy had figured out how to use the contains() function to solve his problem, but I am going to blog this because...(read more)

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• Getting My Head Around Immutability

  - by Michael Mangold

  I'm new to object-oriented programming, and one concept that has been taking me a while to grasp is immutability. I think the light bulb went off last night but I want to verify: When I come across statements that an immutable object cannot be changed, I'm puzzled because I can, for instance, do the following: NSString *myName = @"Bob"; myName = @"Mike"; There, I just changed myName, of immutable type NSString. My problem is that the word, "object" can refer to the physical object in memory, or the abstraction, "myName." The former definition applies to the concept of immutability. As for the variable, a more clear (to me) definition of immutability is that the value of an immutable object can only be changed by also changing its location in memory, i.e. its reference (also known as its pointer). Is this correct, or am I still lost in the woods?

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• circle - rectangle collision in 2D, most efficient way

  - by john smith

  Suppose I have a circle intersecting a rectangle, what is ideally the least cpu intensive way between the two? method A calculate rectangle boundaries loop through all points of the circle and, for each of those, check if inside the rect. method B calculate rectangle boundaries check where the center of the circle is, compared to the rectangle make 9 switch/case statements for the following positions: top, bottom, left, right top left, top right, bottom left, bottom right inside rectangle check only one distance using the circle's radius depending on where the circle happens t be. I know there are other ways that are definitely better than these two, and if could point me a link to them, would be great but, exactly between those two, which one would you consider to be better, regarding both performance and quality/precision? Thanks in advance.

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• Why use an OO approach instead of a giant "switch" statement?

  - by James P. Wright

  I am working in a .Net, C# shop and I have a coworker that keeps insisting that we should use giant Switch statements in our code with lots of "Cases" rather than more object oriented approaches. His argument consistently goes back to the fact that a Switch statement compiles to a "cpu jump table" and is therefore the fastest option (even though in other things our team is told that we don't care about speed). I honestly don't have an argument against this...because I don't know what the heck he's talking about. Is he right? Is he just talking out his ass? Just trying to learn here.

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• After how much line of code a function should be break down?

  - by Sumeet

  While working on existing code base, I usually come across procedures that contain Abusive use of IF and Switch statements. The procedures consist of overwhelming code, which I think require re-factoring badly. The situation gets worse when I identify that some of these are recursive as well. But this is always a matter of debate as the code is working fine and no one wants to wake up the dragon. But, everyone accepts it is very expensive code to manage. I am wondering if are any recommendations to determine if a particular Method is a culprit and needs a revisit/rewrite , so that it can broken down or polymophized in an effective manner. Are there any Metrics (like no. of lines in procedure) that can be used to identify such segment of code. The checklist or advice to convince everyone, will be great!

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• Help me get started in TDD for web development

  - by Snow_Mac

  I've done a tiny, tiny bit of TDD in building an app for a company that I interned with. We used lots of mocking and wrote lots of assert statements, after reading lots of blogs, I'm convinced that TDD is the way to go, but how do you go about TDD web applications? My main framework is Yii in PHP. My main questions are: What do you test? Models? Controllers? Views? How do you know if the output is correct? All my web apps interact with a DB, are there cavets to that and gotchas? Can I do testing in Netbeans? Can you test form elements or just strictly objects & methods?

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• Learning PHP OOP

  - by Ryan Murphy

  I have been coding PHP for about 2 years now and I THINK that I have a very good grasps of the fundamental parts of PHP, i.e. Functions foreach/IF statements sessions/cookies POST/GET Amongst a few others. I want to move on to learning OOP PHP now, so learning how to use classes and making it a really valuable skill. I have 1 requirement, the source must be a respected source that doesn't teach developers bad habits. I have the book: PHP and MySQL Web Development However, as useful as that is I would like an online source. I would like to know from people with experience in OOP PHP, how and where did they learn OOP PHP. Obviously by doing, but I would really appreciate some great resources which help me along the way.

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• Implementation of instance testing in Java, C++, C#

  - by Jake

  For curiosity purposes as well as understanding what they entail in a program, I'm curious as to how instance testing (instanceof/is/using dynamic_cast in c++) works. I've tried to google it (particularly for java) but the only pages that come up are tutorials on how to use the operator. How do the implementations vary across those langauges? How do they treat classes with identical signatures? Also, it's been drilled into my head that using instance testing is a mark of bad design. Why exactly is this? When is that applicable, instanceof should still be used in methods like .equals() and such right? I was also thinking of this in the context of exception handling, again particularly in Java. When you have mutliple catch statements, how does that work? Is that instance testing or is it just resolved during compilation where each thrown exception would go to?

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• Why use string.Empty over "" when assigning to a string object

  - by dreza

  I've been running StyleCop over my code and one of the recommendations SA1122 is to use string.Empty rather than "" when assigning an empty string to a value. My question is why is this considered best practice. Or, is this considered best practice? I assume there is no compiler difference between the two statements so I can only think that it's a readability thing? UPDATE: Thanks for the answers but it's been kindly pointed out this question has been asked many times already on SO, which in hind-sight I should have considered and searched first before asking here. Some of these especially forward links makes for interesting reading. SO question and answer Jon Skeet answer to question

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• Is using ELSE bad programming?

  - by dave.b

  I've often come across bugs that have been caused by using the ELSE construct. A prime example is something along the lines of: If (passwordCheck() == false){ displayMessage(); }else{ letThemIn(); } To me this screams security problem. I know that passwordCheck is likely to be a boolean, but I wouldn't place my applications security on it. What would happen if its a string, int etc? I usually try to avoid using ELSE, and instead opt for two completely separate IF statements to test for what I expect. Anything else then either gets ignored OR is specifically handled. Surely this is a better way to prevent bugs / security issues entering your app. How do you guys do it?

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• How to SET TIMING ON for parallel upgrades to 12c?

  - by Mike Dietrich

  Have you asked yourself how to get timings in an Oracle Database 12c upgrade for all statements? When you run the parallel upgrade via catctl.pl, the parallel upgrade Perl driving script in Oracle Database 12c, you may also want to get timings written in your logfile during execution. As catctl.pl does not offer an option yet the best way to achieve this is to edit the catupses.sql script in $ORACLE/rdbms/admin as this script will get called all time over and over again throughout all steps of theupgrade run. Just add these lines marked in RED to catupses.sql and start your upgrade: Rem =============================================Rem Call Common session settingsRem =============================================@@catpses.sql Rem =============================================Rem  Set Timing On during the UpgradeRem =============================================SET TIMING ON; Rem =============================================Rem Turn off PL/SQL event used by APPSRem =============================================ALTER SESSION SET EVENTS='10933 trace name context off'; -Mike PS: This may become the default in a future patch set

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• graphical interface when using assembly language

  - by Hellbent

  Im looking to use assembly language to make a great game, not just an average game but a really great game. I want to learn a framework to use in assembly. I know thats not possible without learning the framework in c first. So im thinking of learning sdl in c and then learn, teach myself, how to interpret the program and run it as assembly language code which shouldnt be that hard. Then i will have a window and some graphics routines to display the game while using assembly to code everything in. I need to spend some time learning sdl and then some more time learning how to code all those statements using assembly while calling c functions and knowing what registers returned calls use and what they leave etc. My question is , Is this a good way to go or is there something better to get a graphical window display using assembly language? Regards HellBent

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• Clarification of "avoid if-else" advice [duplicate]

  - by deviDave

  This question already has an answer here: Elegant ways to handle if(if else) else 21 answers The experts in clean code advise not to use if/else since it's creating an unreadable code. They suggest rather using IF and not to wait till the end of a method without real need. Now, this if/else advice confuses me. Do they say that I should not use if/else at all (!) or to avoid if/else nesting? Also, if they refer to the nesting of if/else, should I not do even a single nesting or I should limit it to max 2 nestings (as some recommends)? When I say single nesting, I mean this: if (...) { if (...) { } else { } } else { } EDIT Also tools like Resharper will suggest reformatting if/else statements. It usually concerts them to if stand-alone statement, and sometimes even to ternary expression.

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• Is a finite state machine an appropriate solution for this situation?

  - by user1936

  I was writing some test code as an example where I had a washing machine class. It has a door state that should be open or closed, and also a running state, either on or off. I want to prevent the running state from changing from 'off' to 'on' when the door is 'open', and also prevent the door from being set to 'open' while the machine is 'on'. I have this functionality rigged up with a bunch of if statements. It feels inelegant and it could quickly turn into spaghetti code if I want to add another state that puts additional conditions on the changes of other states. I wonder, is a finite state machine a solution for this situation? Would it simplify adding states and defining valid transitions?

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• Techniques for Working Without a Debugger [closed]

  - by ashes999

  Possible Duplicate: How to effectively do manual debugging? Programming in a debugger is ideal. When I say a debugger, I mean something that will allow you to: Pause execution in the middle of some code (like a VM) Inspect variable values Optionally set variable values and call methods Unfortunately, we're not always blessed to work in environments that have debuggers. This can be for reasons such as: Debugger is too too too slow (Flash circa Flash 8) Interpreted language (Ruby, PHP) Scripting language (eg. inside RPG Maker XP) My question is, what is an effective way to debug without a debugger? The old method of "interleave code with print statements" is time-consuming and not sufficient.

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• How can I determine whether a shellscript runs as root or not?

  - by EvilPhoenix

  This is something I've been curious about. I make a lot of small bash scripts (.sh files) to do tasks that I routinely do. Some of those tasks require everything to be ran as superuser. I've been curious: Is it possible to, within the BASH script prior to everything being run, check if the script is being run as superuser, and if not, print a message saying You must be superuser to use this script, then subsequently terminate the script itself. The other side of that is I'd like to have the script run when the user is superuser, and not generate the error. Any ideas on coding (if statements, etc.) on how to execute the aforementioned?

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• How was 20Q made?

  - by Dan the Man

  Ever since I was a kid, I've wondered how they made the 20Q electronic game. In this game, which is it's on device, you think of an object, thing, or animal (e.g. a potato or a donkey), once you mentally choose your thing, the device goes through a series of questions such as: Is it larger than a loaf of bread? Is it found outdoors? Is it used for recreation? For each of the questions you can answer yes, no, maybe, or unknown. The way I've always thought of it to work was with immense, nested conditionals (if statements). But, I don't think that would be very likely as it would be terribly difficult to understand while coding it. I'm not looking for a discussion as SE doesn't allow it; I'm looking for concrete knowledge or solutions.

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• Are unit tests really used as documentation?

  - by stijn

  I cannot count the number of times I read statements in the vein of 'unit tests are a very important source of documentation of the code under test'. I do not deny they are true. But personally I haven't found myself using them as documentation, ever. For the typical frameworks I use, the method declarations document their behaviour and that's all I need. And I assume the unit tests backup everything stated in that documentation, plus likely some more internal stuff, so on one side it duplicates the ducumentation while on the other it might add some more that is irrelevant. So the question is: when are unit tests used as documentation? When the comments do not cover everything? By developpers extending the source? And what do they expose that can be useful and relevant that the documentation itself cannot expose?

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