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• Quick Question, robots.txt Disallow: /*/ does what exactly?

  - by Exit

  A SEO firm suggested changing the robots.txt to: User-agent: * Disallow: /*/ Allow: /ims/ I'm not sure what that would do, but my guess is that is would tell all robots to index nothing but the ims folder. I understand the wildcard, but I'm confused by the slashes and don't know how they would play out in conjunction with the wildcard. * Update * I didn't mention that there is a sitemap listed in the robots.txt file, but according to one tech blogger, he realized that sitemaps trump robots exclusions. So, even though this says in Google Webmaster Tools that everything with a trailing slash will not be indexed, the sitemap contains the important links. I did notice that the link count on Google went from 360 to 336, and the sitemap links under the URL scaled back to 3 from 6. I'm not sure the cause or what links were removed, though. Perhaps it cleaned out garbage. I'm still clueless why they would add in 'Allow: /ims/', that seems pointless. And a quick list of what would index according to the robots rules above (withouth the sitemap) using /*/: domain.com Indexed domain.com/page.html Indexed domain.com/folder/ Not Indexed domain.com/folder/page.html Not Indexed

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• Vector with Constant-Time Remove - still a Vector?

  - by Darrel Hoffman

  One of the drawbacks of most common implementations of the Vector class (or ArrayList, etc. Basically any array-backed expandable list class) is that their remove() operation generally operates in linear time - if you remove an element, you must shift all elements after it one space back to keep the data contiguous. But what if you're using a Vector just to be a list-of-things, where the order of the things is irrelevant? In this case removal can be accomplished in a few simple steps: Swap element to be removed with the last element in the array Reduce size field by 1. (No need to re-allocate the array, as the deleted item is now beyond the size field and thus not "in" the list any more. The next add() will just overwrite it.) (optional) Delete last element to free up its memory. (Not needed in garbage-collected languages.) This is clearly now a constant-time operation, since only performs a single swap regardless of size. The downside is of course that it changes the order of the data, but if you don't care about the order, that's not a problem. Could this still be called a Vector? Or is it something different? It has some things in common with "Set" classes in that the order is irrelevant, but unlike a Set it can store duplicate values. (Also most Set classes I know of are backed by a tree or hash map rather than an array.) It also bears some similarity to Heap classes, although without the log(N) percolate steps since we don't care about the order.

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• CheckMemoryAllocationGame Sample

  - by Michael B. McLaughlin

  Many times I’ve found myself wondering how much GC memory some operation allocates. This is primarily in the context of XNA games due to the desire to avoid generating garbage and thus triggering a GC collection. Many times I’ve written simple programs to check allocations. I did it again recently. It occurred to me that many XNA developers find themselves asking this question from time to time. So I cleaned up my sample and published it on my website. Feel free to download it and put it to use. It’s rather thoroughly commented. The location where you insert the code you wish to check is in the Update method found in Game1.cs. The default that I put in is a line of code that generates a new Guid using Guid.NewGuid (which, if you’re curious, does not create any heap allocations). Read all of the comments in the Update method (at the very least) to make sure that your code is measured properly. It’s important to make sure that you meaningfully reference any thing you create after the second call to get the memory or else (in Release configuration at least) you will likely get incorrect results. Anyway, it should make sense when you read the comments and if not, feel free to post a comment here or ask me on Twitter. You can find my utilities and code samples page here: http://www.bobtacoindustries.com/developers/utils/Default.aspx To download CheckMemoryAllocationGame’s source code directly: http://www.bobtacoindustries.com/developers/utils/CheckMemoryAllocationGame.zip (If you’re looking to do this outside of the context of an XNA game, the measurement code in the Update method can easily be adapted into, e.g., a C# Windows Console application. In the past I mostly did that, actually. But I didn’t feel like adding references to all the XNA assemblies this time and… anyway, if you want you can easily convert it to a console application. If there’s any demand for it, I’ll do it myself and update this post when I get a chance.)

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• the OpenJDK group at Oracle is growing

  - by john.rose

  p.p1 {margin: 0.0px 0.0px 12.0px 0.0px; font: 12.0px Times} span.s1 {text-decoration: underline ; color: #0000ee} The OpenJDK software development team at Oracle is hiring. To get an idea of what we’re looking for, go to the Oracle recruitment portal and enter the Keywords “Java Platform Group” and the Location Keywords “Santa Clara”.  (We are a global engineering group based in Santa Clara.)  It’s pretty obvious what we are working on; just dive into a public OpenJDK repository or OpenJDK mailing list. Here is a typical job description from the current crop of requisitions: The Java Platform group is looking for an experienced, passionate and highly-motivated Software Engineer to join our world class development effort. Our team is responsible for delivering the Java Virtual Machine that is used by millions of developers. We are looking for a development engineer with a strong technical background and thorough understanding of the Java Virtual Machine, Java execution runtime, classloading, garbage collection, JIT compiler, serviceability and a desire to drive innovations. As a member of the software engineering division, you will take an active role in the definition and evolution of standard practices and procedures. You will be responsible for defining and developing software for tasks associated with the developing, designing and debugging of software applications or operating systems. Work is non-routine and very complex, involving the application of advanced technical/business skills in area of specialization. Leading contributor individually and as a team member, providing direction and mentoring to others. BS or MS degree or equivalent experience relevant to functional area. 7 years of software engineering or related experience.

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• Input Handling and Game loop

  - by Bob Coder

  So, I intercept the WM_KEYDOWN and other messages. Thing is, my game can't/shouldn't react to these messages just yet, since my game might be currently drawing to the screen or in the middle of updating my game entities. So the idea is to keep a keyboardstate and mousestate, which is updated by the part of my code that intercepts the windows messages. These states just keep track of which keys/buttons are currently pressed. Then, at the start of my game's update function, I access these keyboard and mouse states and my game reacts to the user input. Now, which is the best way to access these states? I assume that windows messages can be sent whenever, so the keyboard/mouse states are constantly being edited. Accessing say a list of currently pressed keys in the keyboard state the same time another part of the code is editing the list would cause problems. Should I make a deep copy of a state and act on that? How would I deal with the garbage generated though, this would take place every frame.

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• C Programming matrix

  - by Bilal Khan

  In this program the user enters the # of columns of the matrix and then the entries of the matrix. So, for example, if the user enters 2 for column # and 1 2 3 4 for entries then the program develops a 2 by 2 matrix with 1 2 3 4 as entries. My program works perfectly in such a case. However, if the user for example had only entered 1 2 3 then my program makes a matrix with garbage values. I would like the program in such a case to exit the program. It is a simple question, but it has me baffled. #include<stdio.h> #include<stdlib.h> int main() { int m,x, n, c = 0, d,k, matrix[10][10], transpose[10][10], product[10][10]; printf("Enter the number of columns of matrix "); scanf("%d",&m); if(m<=0){ printf("You entered a invalid value."); exit(0); } else{ printf("Enter the elements of matrix \n"); for( c = 0 ; c < 10 ; c++ ) { for( d = 0 ; d < m ; d++ ) { scanf("%d",&matrix[c][d]); if (matrix[c][d] == 99) // 'x' is character variable I declared to use as a break break; // c = c+1; } if (matrix[c][d] == 99) break; } } printf("\nHere is your matrix:\n"); int i; for(i=0;i<c;i++) { for(d=0;d<m;d++) { printf("%3d ",matrix[i][d]); } printf("\n"); }

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• Google+ Platform Office Hours for June 13th, 2012

  Google+ Platform Office Hours for June 13th, 2012 Here are the show notes for this week's office hours. This week was devoted to your questions and our answers. We covered a wide breadth of topics. 0:43 - Introductions 2:54 - About Tabletop Forge's KickStarter - goo.gl 10:00 - Can I run multiple Hangout Apps at the same time? 12:28 - Is Google looking into adding more powerful Hangout moderation controls? 13:47 - How do you use Hangout Apps with Hangouts on Air? - +Fraser Cain's tips and tricks for Hangouts on Air: goo.gl 23:40 - I have an Android game. How do I port it to the Hangouts API? 27:57 - Pre-hangout Apps, Hangouts on Air pre-rolls, scheduling hangouts and other ways to help viewers find your Hangouts on Air 33:55 - How do I bookmark useful Google+ posts with Google+? 38:13 - Can you add a host ID field to the Hangouts API? When will the overlay garbage collection improve? 40:17 - Hand movement tracking as part of the Hangouts API Thanks to everyone who joined the hangout and asked questions on Google+! From: GoogleDevelopers Views: 698 18 ratings Time: 44:16 More in Science & Technology

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• Analyzing Memory Usage: Java vs C++ Negligible?

  - by Anthony

  How does the memory usage of an integer object written in Java compare\contrast with the memory usage of a integer object written in C++? Is the difference negligible? No difference? A big difference? I'm guessing it's the same because an int is an int regardless of the language (?) The reason why I asked this is because I was reading about the importance of knowing when a program's memory requirements will prevent the programmer from solving a given problem. What fascinated me is the amount of memory required for creating a single Java object. Take for example, an integer object. Correct me if I'm wrong but a Java integer object requires 24 bytes of memory: 4 bytes for its int instance variable 16 bytes of overhead (reference to the object's class, garbage collection info & synchronization info) 4 bytes of padding As another example, a Java array (which is implemented as an object) requires 48+bytes: 24 bytes of header info 16 bytes of object overhead 4 bytes for length 4 bytes for padding plus the memory needed to store the values How do these memory usages compare with the same code written in C++? I used to be oblivious about the memory usage of the C++ and Java programs I wrote, but now that I'm beginning to learn about algorithms, I'm having a greater appreciation for the computer's resources.

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• C++ Iterator lifetime and detecting invalidation

  - by DK.

  Based on what's considered idiomatic in C++11: should an iterator into a custom container survive the container itself being destroyed? should it be possible to detect when an iterator becomes invalidated? are the above conditional on "debug builds" in practice? Details: I've recently been brushing up on my C++ and learning my way around C++11. As part of that, I've been writing an idiomatic wrapper around the uriparser library. Part of this is wrapping the linked list representation of parsed path components. I'm looking for advice on what's idiomatic for containers. One thing that worries me, coming most recently from garbage-collected languages, is ensuring that random objects don't just go disappearing on users if they make a mistake regarding lifetimes. To account for this, both the PathList container and its iterators keep a shared_ptr to the actual internal state object. This ensures that as long as anything pointing into that data exists, so does the data. However, looking at the STL (and lots of searching), it doesn't look like C++ containers guarantee this. I have this horrible suspicion that the expectation is to just let containers be destroyed, invalidating any iterators along with it. std::vector certainly seems to let iterators get invalidated and still (incorrectly) function. What I want to know is: what is expected from "good"/idiomatic C++11 code? Given the shiny new smart pointers, it seems kind of strange that STL allows you to easily blow your legs off by accidentally leaking an iterator. Is using shared_ptr to the backing data an unnecessary inefficiency, a good idea for debugging or something expected that STL just doesn't do? (I'm hoping that grounding this to "idiomatic C++11" avoids charges of subjectivity...)

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• Does immutability entirely eliminate the need for locks in multi-processor programming?

  - by GlenPeterson

  Part 1 Clearly Immutability minimizes the need for locks in multi-processor programming, but does it eliminate that need, or are there instances where immutability alone is not enough? It seems to me that you can only defer processing and encapsulate state so long before most programs have to actually DO something. If a program performs actions on multiple processors, something needs to collect and aggregate the results. All this involves multi-process communication before, after, and possibly during some transformations. The start and end state of the machines are different. Can this always be done with no locks just by throwing out each object and creating a new one instead of changing the original (a crude view of immutability)? What cases still require locking? I'm interested in both the theoretical/academic answer and the practical/real-world answer. I know a lot of functional programmers like to talk about "no side effect" but in the "real world" everything has a side effect. Every processor click takes time and electricity and machine resources away from other processes. So I understand that there may be more than one perspective to answer this question from. If immutability is safe, given certain bounds or assumptions, I want to know what the borders of the "safety zone" are exactly. Some examples of possible boundaries: I/O Exceptions/errors Interfaces with programs written in other languages Interfaces with other machines (physical, virtual, or theoretical) Special thanks to @JimmaHoffa for his comment which started this question! Part 2 Multi-processor programming is often used as an optimization technique - to make some code run faster. When is it faster to use locks vs. immutable objects? Given the limits set out in Amdahl's Law, when can you achieve better over-all performance (with or without the garbage collector taken into account) with immutable objects vs. locking mutable ones? Summary I'm combining these two questions into one to try to get at where the bounding box is for Immutability as a solution to threading problems.

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• Installing Ubuntu 12.04 on a single GPT SSD which contains Windows 7

  - by Gary

  I recently bought a brand new 64 bit PC with a (ASUS) motherboard that supports UEFI and a GPT formatted 240Gb SSD, which contains Windows 7 in the first of 3 (80Gb) partitions. When the system arrived, it booted into Windows 7 like a dream, with no problems. I did not originally want Windows, but the manufacturer does not work with Linux (of any flavour), so I thought I would install Ubuntu into the second partition and dual boot. I downloaded the 12.04 64bit version and proceeded to install. Having selected to 'install', the screen became corrupted, with multicoloured garbage across the middle third of the screen !! So, I rebooted and --- MISSING OPERATING SYSTEM !!! The only way I can now get into Windows is via Super Grub2. First question - what went wrong ? 2nd - Will Ubuntu install on a GPT disk partition ? 3rd - Will it install alongside Windows 7 without screwing the boot mechanism ? 4th - How do I do it ? I have scoured the internet looking for appropriate answers and found NONE ! Please help.......

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• Ubuntu 12.04 using b43-fwcutter

  - by Nathan

  I have used 10.04 with the b43-fwcutter driver to drive my BCM4318 Broadcom card (a Linksys WPC54G v3) on my old Dell Inspiron 8100 for two years+ with no troubles. I just upgraded to 12.04 and although everything worked fine after install, before I added the b43-fwcutter driver, once I installed the driver, the system refuses to boot. Even before I install the Linksys card!! It just hangs on boot with graphical garbage on the screen. I tried several attempts to recover the system using the live CD, and finally reinstalled completely. I have been thru the cycle, install fresh system, verify everything works, then install b43-fwcutter and it is hung, several times. Consistent hard fail. The system runs fine on hardwire Ethernet, and wireless was fine on 10.04. But I cannot get there with 12.04. So after several attempts, I am now ready to admit defeat and ask for help. I have read every thread that search turned up, and either the advice is to do what I did, i.e. install fwcutter, or does not apply (Different Broadcom, STA, legacy, whatever) So what do I need to do to fix it? Or is the B43-fwcutter driver broken for 12.04? Thoughts? Tips? Log files needed??

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• Oracle NoSQL Database: Cleaner Performance

  - by Charles Lamb

  In an earlier post I noted that Berkeley DB Java Edition cleaner performance had improved significantly in release 5.x. From an Oracle NoSQL Database point of view, this is important because Berkeley DB Java Edition is the core storage engine for Oracle NoSQL Database. Many contemporary NoSQL Databases utilize log based (i.e. append-only) storage systems and it is well-understood that these architectures also require a "cleaning" or "compaction" mechanism (effectively a garbage collector) to free up unused space. 10 years ago when we set out to write a new Berkeley DB storage architecture for the BDB Java Edition ("JE") we knew that the corresponding compaction mechanism would take years to perfect. "Cleaning", or GC, is a hard problem to solve and it has taken all of those years of experience, bug fixes, tuning exercises, user deployment, and user feedback to bring it to the mature point it is at today. Reports like Vinoth Chandar's where he observes a 20x improvement validate the maturity of JE's cleaner. Cleaner performance has a direct impact on predictability and throughput in Oracle NoSQL Database. A cleaner that is too aggressive will consume too many resources and negatively affect system throughput. A cleaner that is not aggressive enough will allow the disk storage to become inefficient over time. It has to Work well out of the box, and Needs to be configurable so that customers can tune it for their specific workloads and requirements. The JE Cleaner has been field tested in production for many years managing instances with hundreds of GBs to TBs of data. The maturity of the cleaner and the entire underlying JE storage system is one of the key advantages that Oracle NoSQL Database brings to the table -- we haven't had to reinvent the wheel.

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• Release: Oracle Java Development Kit 8, Update 20

  - by Tori Wieldt

  Java Development Kit 8, Update 20 (JDK 8u20) is now available. This latest release of the Java Platform continues to improve upon the significant advances made in the JDK 8 release with new features, security and performance optimizations. These include: new enterprise-focused administration features available in Oracle Java SE Advanced; products offering greater control of Java version compatibility; security updates; and a very useful new feature, the MSI compatible installer. Download Release Notes Java SE 8 Documentation New tools, features and enhancements highlighted from JDK 8 Update 20 are: Advanced Management Console The Java Advanced Management Console 1.0 (AMC) is available for use with the Oracle Java SE Advanced products. AMC employs the Deployment Rule Set (DRS) security feature, along with other functionality, to give system administrators greater and easier control in managing Java version compatibility and security updates for desktops within their enterprise and for ISVs with Java-based applications and solutions. MSI Enterprise JRE Installer Available for Windows 64 and 32 bit systems in the Oracle Java SE Advanced products, the MSI compatible installer enables system administrators to provide automated, consistent installation of the JRE across all desktops in the enterprise, free of user interaction requirements. Performance: String de-duplication resulting in a reduced footprint Improved support in G1 Garbage Collection for long running apps. A new 'force' feature in DRS (Deployment Rule Set) which allows system administrators to specify the JRE with which an applet or Java Web Start application will run. This is useful for legacy applications so end users don't need to approve security exceptions to run.  Java Mission Control 5.4 with new ease-of-use enhancements and launcher integration with Eclipse 4.4 JavaFX on ARM Nashorn performance improvement by persisting bytecode after inital compilation There's much more information to be found in the JDK 8u20 Release Notes.

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• Are these advanced/unfair interview questions regarding Java concurrency?

  - by sparc_spread

  Here are some questions I've recently asked interviewees who say they know Java concurrency: Explain the hazard of "memory visibility" - the way the JVM can reorder certain operations on variables that are unprotected by a monitor and not declared volatile, such that one thread may not see the changes made by another thread. Usually I ask this one by showing code where this hazard is present (e.g. the NoVisibility example in Listing 3.1 from "Java Concurrency in Practice" by Goetz et al) and asking what is wrong. Explain how volatile affects not just the actual variable declared volatile, but also any changes to variables made by a thread before it changes the volatile variable. Why might you use volatile instead of synchronized? Implement a condition variable with wait() and notifyAll(). Explain why you should use notifyAll(). Explain why the condition variable should be tested with a while loop. My question is - are these appropriate or too advanced to ask someone who says they know Java concurrency? And while we're at it, do you think that someone working in Java concurrency should be expected to have an above-average knowledge of Java garbage collection?

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• Most suited technology for browser games?

  - by Tingle

  I was thinking about making a 2D MMO which I would in the long run support on various plattforms like desktop, mac, browser, android and ios. The server will be c++/linux based and the first client would go in the browser. So I have done some research and found that webgl and flash 11 support hardware accelerated rendering, I saw some other things like normal HTML5 painting. So my question is, which technology should I use for such a project? My main goal would be that the users have a hassle free experience using what there hardware can give them with hardware acceleration. And the client should work on the most basic out-of-the-box pc's that any casual pc or mac user has. And another criteria would be that it should be developer friendly. I've messed with webgl abit for example and that would require writing a engine from scratch - which is acceptable but not preferred. Also, in case of non-actionscript, which kind language is most prefered in terms of speed and flexability. I'm not to fond of javascript due to the garbage collector but have learned to work around it. Thank you for you time.

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• Self-imposed lockout from program

  - by Alex

  I'm plagued with a lack of willpower. I recently started looking for solutions, and came across a program for macs called SelfControl which completely blocks one's access to a given set of websites for a given period of time (you can delete the program/restart your computer/do almost anything and it will still block those sites for the specified time period, and doesn't require a password to do it.) Unfortunately, there are no windows analogues. The one that comes the closest is Cold Turkey. It has the functionality whereby you set a time in the future, specify a list of websites (or programs - eg explorer, firefox, chrome) and you are blocked from accessing them for the whole duration. No password can undo it, no system reboot, etc. The problem is that the program is a buggy piece of garbage, and in order to ensure that you're not locked out from websites forever, you have to run an uninstaller which is just an exe file accessible at any time which completely defeats the purpose of a self-imposed program lockout. I want to make a better version of that program, or find a simple way to prevent access to a given set of programs over a given period of time with no way around it. I've only taken a few introductory courses in java (math major), but the internet is really having a negative effect on my studies, and the only way I can do work is to eliminate all distractions. What do I need to learn in order to make a program with the following properties: Given a set of .exe files, and a time in the future , this program will prevent access to the given .exe files until current time = given time restarting the computer doesn't interfere with the program, one can't uninstall the program until current time = given time, one can't create another instance of the program to block itself I don't care how much programming knowledge i need to acquire in order to make this program, so please give me a specific list of things that I need to study in order to make this happen, or if something like this exists, then please let me know.

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• Twinview broken on upgrade to ubuntu 10.10

  - by mapkyca

  I have been on 9.10 for over a year on the grounds that if it ain't broke, don't fix it. However, I had a spare weekend and figured it was probably about time... I performed an upgrade to 10.4, and everything seemed to proceed smoothly, so I took the plunge and went for 10.10. Disaster. My twinview Nvidia display which had been working perfectly is now broken. On boot everything seems fine, but when X starts and the second monitor springs into life the primary winks out and switches off - almost as if its been put into an unsupported display mode. The system seems to think there's a second monitor - the nvidia logo is split across the two screens, but it can't seem to start. Things I've tried: Swapping the monitors (one is older than the other, and its definitely the port not the actual monitor) Rolling back to an old Xorg conf from prior to the upgrade Installing a non-beta driver direct from Nvidia (this seems to start both monitors but then apparently stops boot and causes the second display to 'wink'. Twinview seems non-functional, both displays are mirrors) Disabling EDID Disabling twinview, logging in and attempting to use the Nvidia config to re-detect the monitors (second monitor is falsely detected and won't go higher than 1024x768. Selecting 'apply' causes one screen to go blank and the other to display garbage) googling for about 5 hours looking for similar problems, none of the offered solutions seemed to work I'm at a loss, and it is looking very much like I'm going to have to go through a time consuming reinstall to downgrade back to the working 10.4. Any thoughts?

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• Resource Acquisition is Initialization in C#

  - by codeWithoutFear

  Resource Acquisition Is Initialization (RAII) is a pattern I grew to love when working in C++.  It is perfectly suited for resource management such as matching all those pesky new's and delete's.  One of my goals was to limit the explicit deallocation statements I had to write.  Often these statements became victims of run-time control flow changes (i.e. exceptions, unhappy path) or development-time code refactoring. The beauty of RAII is realized by tying your resource creation (acquisition) to the construction (initialization) of a class instance.  Then bind the resource deallocation to the destruction of that instance.  That is well and good in a language with strong destructor semantics like C++, but languages like C# that run on garbage-collecting runtimes don't provide the same instance lifetime guarantees. Here is a class and sample that combines a few features of C# to provide an RAII-like solution: using System; namespace RAII { public class DisposableDelegate : IDisposable { private Action dispose; public DisposableDelegate(Action dispose) { if (dispose == null) { throw new ArgumentNullException("dispose"); } this.dispose = dispose; } public void Dispose() { if (this.dispose != null) { Action d = this.dispose; this.dispose = null; d(); } } } class Program { static void Main(string[] args) { Console.Out.WriteLine("Some resource allocated here."); using (new DisposableDelegate(() => Console.Out.WriteLine("Resource deallocated here."))) { Console.Out.WriteLine("Resource used here."); throw new InvalidOperationException("Test for resource leaks."); } } } } The output of this program is: Some resource allocated here. Resource used here. Unhandled Exception: System.InvalidOperationException: Test for resource leaks. at RAII.Program.Main(String[] args) in c:\Dev\RAII\RAII\Program.cs:line 40 Resource deallocated here. Code without fear! --Don

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• What is the recommended way to empty a SSD?

  - by Lekensteyn

  I've just received my new SSD since the old one died. This Intel 320 SSD supports TRIM. For testing purposes, my dealer put malware, err, Windows on it. I want to get rid of it and install Kubuntu on it. It does not have to be a "secure wipe", I just need the empty the disk in the mosy healthy way. I believe that dd if=/dev/zero of=/dev/sda just fills the blocks with zeroes and thereby taking another write (correct me if I'm wrong). I've seen the answer How to enable TRIM, but it looks like it's suited for clearing empty blocks, not wiping the disk. hdparm seems to be the program to do it, but I'm not sure if it clears the disk OR cleans empty blocks. From its manual page: --trim-sector-ranges For Solid State Drives (SSDs). EXCEPTIONALLY DANGEROUS. DO NOT USE THIS OPTION!! Tells the drive firmware to discard unneeded data sectors, destroying any data that may have been present within them. This makes those sectors available for immediate use by the firmware's garbage collection mechanism, to improve scheduling for wear-leveling of the flash media. This option expects one or more sector range pairs immediately after the option: an LBA starting address, a colon, and a sector count, with no intervening spaces. EXCEPTIONALLY DANGEROUS. DO NOT USE THIS OPTION!! E.g. hdparm --trim-sector-ranges 1000:4 7894:16 /dev/sdz How can I make all blocks appear as empty using TRIM?

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• What is a good way to refactor a large, terribly written code base by myself? [closed]

  - by AgentKC

  Possible Duplicate: Techniques to re-factor garbage and maintain sanity? I have a fairly large PHP code base that I have been writing for the past 3 years. The problem is, I wrote this code when I was a terrible programmer and now it's tens of thousands of lines of conditionals and random MySQL queries everywhere. As you can imagine, there are a ton of bugs and they are extremely hard to find and fix. So I would like a good method to refactor this code so that it is much more manageable. The source code is quite bad; I did not even use classes or functions when I originally wrote it. At this point, I am considering rewriting the whole thing. I am the only developer and my time is pretty limited. I would like to get this done as quickly as possible, so I can get back to writing new features. Since rewriting the code would take a long time, I am looking for some methods that I can use to clean up the code as quickly as possible without leaving more bad architecture that will come back to haunt me later. So this is the basic question: What is a good way for a single developer to take a fairly large code base that has no architecture and refactor it into something with reasonable architecture that is not a nightmare to maintain and expand?

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• Information I need to know as a Java Developer [on hold]

  - by Woy

  I'm a java developer. I'm trying to get more knowledge to become a better programmer. I've listed a number of technologies to learn. Instead of what I've listed, what technologies would you suggest to learn as well for a Junior Java Developer? I realize, there's a lot of things to study. Java: - how a garbage collector works - resource management - network programming - TCP/IP HTTP - transactions, - consistency: interfaces, classes collections, hash codes, algorithms, comp. complexity concurrent programming: synchronizing, semafores steam management metability: thread-safety byte code manipulations, reflections, Aspect-Oriented Programming as base to understand frameworks such as Spring etc. Web stack: servlets, filters, socket programming Libraries: JDK, GWT, Apache Commons, Joda-Time, Dependency Injections: Spring, Nano Tools: IDE: very good knowledge - debugger - profiler - web analyzers: Wireshark, firebugs - unit testing SQL/Databases: Basics SELECTing columns from a table Aggregates Part 1: COUNT, SUM, MAX/MIN Aggregates Part 2: DISTINCT, GROUP BY, HAVING + Intermediate JOINs, ANSI-89 and ANSI-92 syntax + UNION vs UNION ALL x NULL handling: COALESCE & Native NULL handling Subqueries: IN, EXISTS, and inline views Subqueries: Correlated ITH syntax: Subquery Factoring/CTE Views Advanced Topics Functions, Stored Procedures, Packages Pivoting data: CASE & PIVOT syntax Hierarchical Queries Cursors: Implicit and Explicit Triggers Dynamic SQL Materialized Views Query Optimization: Indexes Query Optimization: Explain Plans Query Optimization: Profiling Data Modelling: Normal Forms, 1 through 3 Data Modelling: Primary & Foreign Keys Data Modelling: Table Constraints Data Modelling: Link/Corrollary Tables Full Text Searching XML Isolation Levels Entity Relationship Diagrams (ERDs), Logical and Physical Transactions: COMMIT, ROLLBACK, Error Handling

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• Sending Emails from existing SMTP host from Ubuntu Server

  - by ezgoodnight

  I feel like my problem is very simple, but I've been trying for quite some time and haven't cracked it. You experienced server guys will probably laugh at this, but I'm finally at the point I need help or I'll never get anywhere. I have a little box running 12.04 LTS and I've wanted to script some status checks and have the server send me an email and schedule this with cron. I basically want a command line mail client that I can set up as easily as Thunderbird to send through my existing SMTP through the command line. Something that can easily be rolled into my bash scripts. I already have a remote host handling our email, SMTP, MTA, all that garbage. I don't particularly want to set up a relay just to send email when I have one that everyone else in the company already uses. I've tried, but there are too many aspects I don't understand AND I don't see why I should set up something local when we already pay for a remote host to do these things. If I absolutely have to set up sendmail or postfix, then so be it, but I'd appreciate a simple alternative. I'm open to practically anything at this point.

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• Use the &ldquo;using&rdquo; statement on objects that implement the IDisposable Interface

  - by mbcrump

  From MSDN : C#, through the .NET Framework common language runtime (CLR), automatically releases the memory used to store objects that are no longer required. The release of memory is non-deterministic; memory is released whenever the CLR decides to perform garbage collection. However, it is usually best to release limited resources such as file handles and network connections as quickly as possible. The using statement allows the programmer to specify when objects that use resources should release them. The object provided to the using statement must implement the IDisposable interface. This interface provides the Dispose method, which should release the object's resources. In my quest to write better, more efficient code I ran across the “using” statement. Microsoft recommends that we specify when to release objects. In other words, if you use the “using” statement this tells .NET to release the object specified in the using block once it is no longer needed.   So Using this block: private static string ReadConfig()         {             const string path = @"C:\SomeApp.config.xml";               using (StreamReader reader = File.OpenText(path))             {                 return reader.ReadToEnd();             }         }   The compiler converts this to: private static string ReadConfig1() {     StreamReader sr = new StreamReader(@"C:\SomeApp.config.xml");       try     {         return sr.ReadToEnd();     }     finally     {         if (sr != null)             ((IDisposable)sr).Dispose();     }   }

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• Is there a better way to organize my module tests that avoids an explosion of new source files?

  - by luser droog

  I've got a neat (so I thought) way of having each of my modules produce a unit-test executable if compiled with the -DTESTMODULE flag. This flag guards a main() function that can access all static data and functions in the module, without #including a C file. From the README: -- Modules -- The various modules were written and tested separately before being coupled together to achieve the necessary basic functionality. Each module retains its unit-test, its main() function, guarded by #ifdef TESTMODULE. `make test` will compile and execute all the unit tests, producing copious output, but importantly exitting with an appropriate success or failure code, so the `make test` command will fail if any of the tests fail. Module TOC __________ test obj src header structures CONSTANTS ---- --- --- --- -------------------- m m.o m.c m.h mfile mtab TABSZ s s.o s.c s.h stack STACKSEGSZ v v.o v.c v.h saverec_ f.o f.c f.h file ob ob.o ob.c ob.h object ar ar.o ar.c ar.h array st st.o st.c st.h string di di.o di.c di.h dichead dictionary nm nm.o nm.c nm.h name gc gc.o gc.c gc.h garbage collector itp itp.c itp.h context osunix.o osunix.c osunix.h unix-dependent functions It's compile by a tricky bit of makefile, m:m.c ob.h ob.o err.o $(CORE) itp.o $(OP) cc $(CFLAGS) -DTESTMODULE $(LDLIBS) -o $@ $< err.o ob.o s.o ar.o st.o v.o di.o gc.o nm.o itp.o $(OP) f.o where the module is compiled with its own C file plus every other object file except itself. But it's creating difficulties for the kindly programmer who offered to write the Autotools files for me. So the obvious way to make it "less weird" would be to bust-out all the main functions into separate source files. But, but ... Do I gotta?

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