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  • Java: custom-exception-error

    - by HH
    $ javac TestExceptions.java TestExceptions.java:11: cannot find symbol symbol : class test location: class TestExceptions throw new TestExceptions.test("If you see me, exceptions work!"); ^ 1 error Code import java.util.*; import java.io.*; public class TestExceptions { static void test(String message) throws java.lang.Error{ System.out.println(message); } public static void main(String[] args){ try { // Why does it not access TestExceptions.test-method in the class? throw new TestExceptions.test("If you see me, exceptions work!"); }catch(java.lang.Error a){ System.out.println("Working Status: " + a.getMessage() ); } } }

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  • Cannot load JRubyEngine because org.apache.bsf.util.BSFEngineImpl not found

    - by Ceilingfish
    Hi, I'm trying to use JRuby in a custom application, and I don't seem to be able to load the JRubyEngine object. My class looks like functionally similar to this: public class ScriptEngine { private static ScriptEngine engine = new JRubyEngine(); public void run(final String script, final Map<String,Object> input) { final Bindings context = engine.createBindings(); context.putAll(input); try { engine.eval(script,context); } catch (ScriptException e) { log.error("Failed to execute script: "+getScript(),e); } } } However this fails at compilation with the complaint: [javac] Compiling 486 source files to /workspace/myProject/build/src [javac] /workspace/myProject/src/net/ceilingfish/ScriptEngine.java:31: cannot access org.apache.bsf.util.BSFEngineImpl [javac] class file for org.apache.bsf.util.BSFEngineImpl not found [javac] private static ScriptEngine engine = new JRubyEngine(); [javac] ^ [javac] 1 error Does anyone have any insights on where I can get this class from? Or if there is a better way to be instantiating a JRubyEngine object.

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  • The Grand Unified Framework Theory

    Tom Janssens left a comment: What still bugs me is that we do not have a unified pattern for all .net dev (using modelbinders and icommand for example...) But, Tom we are pretty close. At least as close as we should be, I think. With .NET there are plenty of low level patterns we can reuse regardless of the application platform or architecture. Stuff like: Asynchronous programming with events or the TPL. Object queries with LINQ. Resource management with IDispose. At a higher...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Hibernate + Spring : cascade deletion ignoring non-nullable constraints

    - by E.Benoît
    Hello, I seem to be having one weird problem with some Hibernate data classes. In a very specific case, deleting an object should fail due to existing, non-nullable relations - however it does not. The strangest part is that a few other classes related to the same definition behave appropriately. I'm using HSQLDB 1.8.0.10, Hibernate 3.5.0 (final) and Spring 3.0.2. The Hibernate properties are set so that batch updates are disabled. The class whose instances are being deleted is: @Entity( name = "users.Credentials" ) @Table( name = "credentials" , schema = "users" ) public class Credentials extends ModelBase { private static final long serialVersionUID = 1L; /* Some basic fields here */ /** Administrator credentials, if any */ @OneToOne( mappedBy = "credentials" , fetch = FetchType.LAZY ) public AdminCredentials adminCredentials; /** Active account data */ @OneToOne( mappedBy = "credentials" , fetch = FetchType.LAZY ) public Account activeAccount; /* Some more reverse relations here */ } (ModelBase is a class that simply declares a Long field named "id" as being automatically generated) The Account class, which is one for which constraints work, looks like this: @Entity( name = "users.Account" ) @Table( name = "accounts" , schema = "users" ) public class Account extends ModelBase { private static final long serialVersionUID = 1L; /** Credentials the account is linked to */ @OneToOne( optional = false ) @JoinColumn( name = "credentials_id" , referencedColumnName = "id" , nullable = false , updatable = false ) public Credentials credentials; /* Some more fields here */ } And here is the AdminCredentials class, for which the constraints are ignored. @Entity( name = "admin.Credentials" ) @Table( name = "admin_credentials" , schema = "admin" ) public class AdminCredentials extends ModelBase { private static final long serialVersionUID = 1L; /** Credentials linked with an administrative account */ @OneToOne( optional = false ) @JoinColumn( name = "credentials_id" , referencedColumnName = "id" , nullable = false , updatable = false ) public Credentials credentials; /* Some more fields here */ } The code that attempts to delete the Credentials instances is: try { if ( account.validationKey != null ) { this.hTemplate.delete( account.validationKey ); } this.hTemplate.delete( account.languageSetting ); this.hTemplate.delete( account ); } catch ( DataIntegrityViolationException e ) { return false; } Where hTemplate is a HibernateTemplate instance provided by Spring, its flush mode having been set to EAGER. In the conditions shown above, the deletion will fail if there is an Account instance that refers to the Credentials instance being deleted, which is the expected behaviour. However, an AdminCredentials instance will be ignored, the deletion will succeed, leaving an invalid AdminCredentials instance behind (trying to refresh that instance causes an error because the Credentials instance no longer exists). I have tried moving the AdminCredentials table from the admin DB schema to the users DB schema. Strangely enough, a deletion-related error is then triggered, but not in the deletion code - it is triggered at the next query involving the table, seemingly ignoring the flush mode setting. I've been trying to understand this for hours and I must admit I'm just as clueless now as I was then.

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  • Informed TDD &ndash; Kata &ldquo;To Roman Numerals&rdquo;

    - by Ralf Westphal
    Originally posted on: http://geekswithblogs.net/theArchitectsNapkin/archive/2014/05/28/informed-tdd-ndash-kata-ldquoto-roman-numeralsrdquo.aspxIn a comment on my article on what I call Informed TDD (ITDD) reader gustav asked how this approach would apply to the kata “To Roman Numerals”. And whether ITDD wasn´t a violation of TDD´s principle of leaving out “advanced topics like mocks”. I like to respond with this article to his questions. There´s more to say than fits into a commentary. Mocks and TDD I don´t see in how far TDD is avoiding or opposed to mocks. TDD and mocks are orthogonal. TDD is about pocess, mocks are about structure and costs. Maybe by moving forward in tiny red+green+refactor steps less need arises for mocks. But then… if the functionality you need to implement requires “expensive” resource access you can´t avoid using mocks. Because you don´t want to constantly run all your tests against the real resource. True, in ITDD mocks seem to be in almost inflationary use. That´s not what you usually see in TDD demonstrations. However, there´s a reason for that as I tried to explain. I don´t use mocks as proxies for “expensive” resource. Rather they are stand-ins for functionality not yet implemented. They allow me to get a test green on a high level of abstraction. That way I can move forward in a top-down fashion. But if you think of mocks as “advanced” or if you don´t want to use a tool like JustMock, then you don´t need to use mocks. You just need to stand the sight of red tests for a little longer ;-) Let me show you what I mean by that by doing a kata. ITDD for “To Roman Numerals” gustav asked for the kata “To Roman Numerals”. I won´t explain the requirements again. You can find descriptions and TDD demonstrations all over the internet, like this one from Corey Haines. Now here is, how I would do this kata differently. 1. Analyse A demonstration of TDD should never skip the analysis phase. It should be made explicit. The requirements should be formalized and acceptance test cases should be compiled. “Formalization” in this case to me means describing the API of the required functionality. “[D]esign a program to work with Roman numerals” like written in this “requirement document” is not enough to start software development. Coding should only begin, if the interface between the “system under development” and its context is clear. If this interface is not readily recognizable from the requirements, it has to be developed first. Exploration of interface alternatives might be in order. It might be necessary to show several interface mock-ups to the customer – even if that´s you fellow developer. Designing the interface is a task of it´s own. It should not be mixed with implementing the required functionality behind the interface. Unfortunately, though, this happens quite often in TDD demonstrations. TDD is used to explore the API and implement it at the same time. To me that´s a violation of the Single Responsibility Principle (SRP) which not only should hold for software functional units but also for tasks or activities. In the case of this kata the API fortunately is obvious. Just one function is needed: string ToRoman(int arabic). And it lives in a class ArabicRomanConversions. Now what about acceptance test cases? There are hardly any stated in the kata descriptions. Roman numerals are explained, but no specific test cases from the point of view of a customer. So I just “invent” some acceptance test cases by picking roman numerals from a wikipedia article. They are supposed to be just “typical examples” without special meaning. Given the acceptance test cases I then try to develop an understanding of the problem domain. I´ll spare you that. The domain is trivial and is explain in almost all kata descriptions. How roman numerals are built is not difficult to understand. What´s more difficult, though, might be to find an efficient solution to convert into them automatically. 2. Solve The usual TDD demonstration skips a solution finding phase. Like the interface exploration it´s mixed in with the implementation. But I don´t think this is how it should be done. I even think this is not how it really works for the people demonstrating TDD. They´re simplifying their true software development process because they want to show a streamlined TDD process. I doubt this is helping anybody. Before you code you better have a plan what to code. This does not mean you have to do “Big Design Up-Front”. It just means: Have a clear picture of the logical solution in your head before you start to build a physical solution (code). Evidently such a solution can only be as good as your understanding of the problem. If that´s limited your solution will be limited, too. Fortunately, in the case of this kata your understanding does not need to be limited. Thus the logical solution does not need to be limited or preliminary or tentative. That does not mean you need to know every line of code in advance. It just means you know the rough structure of your implementation beforehand. Because it should mirror the process described by the logical or conceptual solution. Here´s my solution approach: The arabic “encoding” of numbers represents them as an ordered set of powers of 10. Each digit is a factor to multiply a power of ten with. The “encoding” 123 is the short form for a set like this: {1*10^2, 2*10^1, 3*10^0}. And the number is the sum of the set members. The roman “encoding” is different. There is no base (like 10 for arabic numbers), there are just digits of different value, and they have to be written in descending order. The “encoding” XVI is short for [10, 5, 1]. And the number is still the sum of the members of this list. The roman “encoding” thus is simpler than the arabic. Each “digit” can be taken at face value. No multiplication with a base required. But what about IV which looks like a contradiction to the above rule? It is not – if you accept roman “digits” not to be limited to be single characters only. Usually I, V, X, L, C, D, M are viewed as “digits”, and IV, IX etc. are viewed as nuisances preventing a simple solution. All looks different, though, once IV, IX etc. are taken as “digits”. Then MCMLIV is just a sum: M+CM+L+IV which is 1000+900+50+4. Whereas before it would have been understood as M-C+M+L-I+V – which is more difficult because here some “digits” get subtracted. Here´s the list of roman “digits” with their values: {1, I}, {4, IV}, {5, V}, {9, IX}, {10, X}, {40, XL}, {50, L}, {90, XC}, {100, C}, {400, CD}, {500, D}, {900, CM}, {1000, M} Since I take IV, IX etc. as “digits” translating an arabic number becomes trivial. I just need to find the values of the roman “digits” making up the number, e.g. 1954 is made up of 1000, 900, 50, and 4. I call those “digits” factors. If I move from the highest factor (M=1000) to the lowest (I=1) then translation is a two phase process: Find all the factors Translate the factors found Compile the roman representation Translation is just a look-up. Finding, though, needs some calculation: Find the highest remaining factor fitting in the value Remember and subtract it from the value Repeat with remaining value and remaining factors Please note: This is just an algorithm. It´s not code, even though it might be close. Being so close to code in my solution approach is due to the triviality of the problem. In more realistic examples the conceptual solution would be on a higher level of abstraction. With this solution in hand I finally can do what TDD advocates: find and prioritize test cases. As I can see from the small process description above, there are two aspects to test: Test the translation Test the compilation Test finding the factors Testing the translation primarily means to check if the map of factors and digits is comprehensive. That´s simple, even though it might be tedious. Testing the compilation is trivial. Testing factor finding, though, is a tad more complicated. I can think of several steps: First check, if an arabic number equal to a factor is processed correctly (e.g. 1000=M). Then check if an arabic number consisting of two consecutive factors (e.g. 1900=[M,CM]) is processed correctly. Then check, if a number consisting of the same factor twice is processed correctly (e.g. 2000=[M,M]). Finally check, if an arabic number consisting of non-consecutive factors (e.g. 1400=[M,CD]) is processed correctly. I feel I can start an implementation now. If something becomes more complicated than expected I can slow down and repeat this process. 3. Implement First I write a test for the acceptance test cases. It´s red because there´s no implementation even of the API. That´s in conformance with “TDD lore”, I´d say: Next I implement the API: The acceptance test now is formally correct, but still red of course. This will not change even now that I zoom in. Because my goal is not to most quickly satisfy these tests, but to implement my solution in a stepwise manner. That I do by “faking” it: I just “assume” three functions to represent the transformation process of my solution: My hypothesis is that those three functions in conjunction produce correct results on the API-level. I just have to implement them correctly. That´s what I´m trying now – one by one. I start with a simple “detail function”: Translate(). And I start with all the test cases in the obvious equivalence partition: As you can see I dare to test a private method. Yes. That´s a white box test. But as you´ll see it won´t make my tests brittle. It serves a purpose right here and now: it lets me focus on getting one aspect of my solution right. Here´s the implementation to satisfy the test: It´s as simple as possible. Right how TDD wants me to do it: KISS. Now for the second equivalence partition: translating multiple factors. (It´a pattern: if you need to do something repeatedly separate the tests for doing it once and doing it multiple times.) In this partition I just need a single test case, I guess. Stepping up from a single translation to multiple translations is no rocket science: Usually I would have implemented the final code right away. Splitting it in two steps is just for “educational purposes” here. How small your implementation steps are is a matter of your programming competency. Some “see” the final code right away before their mental eye – others need to work their way towards it. Having two tests I find more important. Now for the next low hanging fruit: compilation. It´s even simpler than translation. A single test is enough, I guess. And normally I would not even have bothered to write that one, because the implementation is so simple. I don´t need to test .NET framework functionality. But again: if it serves the educational purpose… Finally the most complicated part of the solution: finding the factors. There are several equivalence partitions. But still I decide to write just a single test, since the structure of the test data is the same for all partitions: Again, I´m faking the implementation first: I focus on just the first test case. No looping yet. Faking lets me stay on a high level of abstraction. I can write down the implementation of the solution without bothering myself with details of how to actually accomplish the feat. That´s left for a drill down with a test of the fake function: There are two main equivalence partitions, I guess: either the first factor is appropriate or some next. The implementation seems easy. Both test cases are green. (Of course this only works on the premise that there´s always a matching factor. Which is the case since the smallest factor is 1.) And the first of the equivalence partitions on the higher level also is satisfied: Great, I can move on. Now for more than a single factor: Interestingly not just one test becomes green now, but all of them. Great! You might say, then I must have done not the simplest thing possible. And I would reply: I don´t care. I did the most obvious thing. But I also find this loop very simple. Even simpler than a recursion of which I had thought briefly during the problem solving phase. And by the way: Also the acceptance tests went green: Mission accomplished. At least functionality wise. Now I´ve to tidy up things a bit. TDD calls for refactoring. Not uch refactoring is needed, because I wrote the code in top-down fashion. I faked it until I made it. I endured red tests on higher levels while lower levels weren´t perfected yet. But this way I saved myself from refactoring tediousness. At the end, though, some refactoring is required. But maybe in a different way than you would expect. That´s why I rather call it “cleanup”. First I remove duplication. There are two places where factors are defined: in Translate() and in Find_factors(). So I factor the map out into a class constant. Which leads to a small conversion in Find_factors(): And now for the big cleanup: I remove all tests of private methods. They are scaffolding tests to me. They only have temporary value. They are brittle. Only acceptance tests need to remain. However, I carry over the single “digit” tests from Translate() to the acceptance test. I find them valuable to keep, since the other acceptance tests only exercise a subset of all roman “digits”. This then is my final test class: And this is the final production code: Test coverage as reported by NCrunch is 100%: Reflexion Is this the smallest possible code base for this kata? Sure not. You´ll find more concise solutions on the internet. But LOC are of relatively little concern – as long as I can understand the code quickly. So called “elegant” code, however, often is not easy to understand. The same goes for KISS code – especially if left unrefactored, as it is often the case. That´s why I progressed from requirements to final code the way I did. I first understood and solved the problem on a conceptual level. Then I implemented it top down according to my design. I also could have implemented it bottom-up, since I knew some bottom of the solution. That´s the leaves of the functional decomposition tree. Where things became fuzzy, since the design did not cover any more details as with Find_factors(), I repeated the process in the small, so to speak: fake some top level, endure red high level tests, while first solving a simpler problem. Using scaffolding tests (to be thrown away at the end) brought two advantages: Encapsulation of the implementation details was not compromised. Naturally private methods could stay private. I did not need to make them internal or public just to be able to test them. I was able to write focused tests for small aspects of the solution. No need to test everything through the solution root, the API. The bottom line thus for me is: Informed TDD produces cleaner code in a systematic way. It conforms to core principles of programming: Single Responsibility Principle and/or Separation of Concerns. Distinct roles in development – being a researcher, being an engineer, being a craftsman – are represented as different phases. First find what, what there is. Then devise a solution. Then code the solution, manifest the solution in code. Writing tests first is a good practice. But it should not be taken dogmatic. And above all it should not be overloaded with purposes. And finally: moving from top to bottom through a design produces refactored code right away. Clean code thus almost is inevitable – and not left to a refactoring step at the end which is skipped often for different reasons.   PS: Yes, I have done this kata several times. But that has only an impact on the time needed for phases 1 and 2. I won´t skip them because of that. And there are no shortcuts during implementation because of that.

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  • Ugly thing and advantage of anonymos method -C#

    - by nettguy
    I was asked to explain the ugly thing and advantages of anonymous method. I explained possibly Ugly thing anonymous methods turning quickly into spaghetti code. Advantages We can produce thread safe code using anonymous method :Example static List<string> Names = new List<string>( new string[] { "Jon Skeet", "Marc Gravell", "David", "Bill Gates" }); static List<string> FindNamesStartingWith(string startingText) { return Names.FindAll( delegate(string name) { return name.StartsWith(startingText); }); } But really i did not know whether it is thread safe or not.I was asked to justify it. Can any one help me to understand (1) advantages of anonymous methods (2) Is the above code thread safe or not?

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  • Generate Multiple Choice Questions [closed]

    - by Daniel
    I'm working on a quiz application that will have a number of multiple choice questions. I'm waiting on the content from the client, but I'm hoping to start testing with some placeholder data for the time being. In order for the tests to be worthwhile, I probably need at least 100 multiple choice questions. I wanted to see if anyone knows of a resource or tool that can generate questions/multiple choice answers or propose another creative way to fill my quiz application with placeholder content. Ultimately the data will be in a MySQL database, but I don't really care what format the sample data is in (Excel, Word, JSON, etc.).

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  • A question in java.lang.Integer internal code

    - by Daziplqa
    Hi folks, While looking in the code of the method: Integer.toHexString I found the following code : public static String toHexString(int i) { return toUnsignedString(i, 4); } private static String toUnsignedString(int i, int shift) { char[] buf = new char[32]; int charPos = 32; int radix = 1 << shift; int mask = radix - 1; do { buf[--charPos] = digits[i & mask]; i >>>= shift; } while (i != 0); return new String(buf, charPos, (32 - charPos)); } The question is, in toUnsignedString, why we create a char arr of 32 chars?

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  • Fusion Applications Outreach Continues: Europe

    - by mvaughan
    By Misha Vaughan, Applications User Experience The Oracle Applications User Experience team recently completed training in Europe for a select group of Oracle application solution consultants. The goal was to educate them about Oracle's investment in the Fusion User Experience. This group of newly trained Applications User Experience Sales Ambassadors (SAMBA), continues a program of educational outreach about Oracle's investment in usability across the suites. Katie Candland, Director, Applications User Experience, talks about the Fusion User Experience in Munich, Germany, recently. If you would like to hear more about the Fusion User Experience, Oracle's deep investment in this space, and how it extends to our existing product lines including JD Edwards, Siebel, E-Business Suite, and more, feel free to contact us. We can point you to a resource local to your area, including specially trained speakers 

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  • How do I install Zimbra Desktop in an Ubuntu-friendly way?

    - by d3vid
    I'd like to install Zimbra Desktop but I'm worried about picking logical installation locations and how it will integrate with the Unity desktop. If it doesn't appear in the Messaging Menu there isn't much I can do about that, but what about the launcher? There doesn't seem to be PPA or similar resource. These instructions for 10.10 seem complete: http://www.ubuntugeek.com/how-to-install-zimbra-desktop-on-ubuntu-10-10-maverick.html 6 If you would, accept the default directori where it install /opt/zimbra/zdesktop Is this the logical location for Ubuntu? 9 Now you’ll be asked about where to install files, for example: Home//.zdesktop Sounds right. Is it? 10 And then you’ll be asked about the path where to locate the icon where you’ll launch Zimbra, for example: /home//Desktop How about this?

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  • Django template not loading properly

    - by fmsf
    Hey, When this one runs everything goes fine: (r"^newobject$", "views.myobjects.newobject"), All the CSS + JS files are properly fetched from: static/css/... static/js/... When this one runs: (r"^mybjects/(([a-z]|[A-Z]|[0-9])+)$","views.myobjects.loadobject"), All the css and JS files that are being fetched, are run trough the urlpatterns and are returning my defailt page: (r"", 'views.main.index'), This makes all my CSS and JS code to actualy be HTML. My guess is that i'm giving some noob mistake. Is there any common reason why this should happen? And how to fix it?

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  • Best exception handling practices or recommendations?

    - by user828584
    I think the two main problems with my programs are my code structure/organization and my error handling. I'm reading Code Complete 2, but I need something to read for working with potential problems. For example, on a website, if something can only happen if the user tampers with data via javascript, do you write for that? Also, when do you not catch errors? When you write a class that expects a string and an int as input, and they aren't a string and int, do you check for that, or do you let it bubble up to the calling method that passed incorrect parameters? I know this is a broad topic that can't be answered in a single answer here, so what I'm looking for is a book or resource that's commonly accepted as teaching proper exception handling practice.

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  • How do I handle all the exceptions in a C# class where both ctor and finalizer throw exceptions?

    - by Frank
    How can I handle all exceptions for a class similar to the following under certain circumstances? class Test : IDisposable { public Test() { throw new Exception("Exception in ctor"); } public void Dispose() { throw new Exception("Exception in Dispose()"); } ~Test() { this.Dispose(); } } I tried this but it doesn't work: static void Main() { Test t = null; try { t = new Test(); } catch (Exception ex) { Console.Error.WriteLine(ex.Message); } // t is still null } I have also tried to use "using" but it does not handle the exception thrown from ~Test(); static void Main() { try { using (Test t = new Test()) { } } catch (Exception ex) { Console.Error.WriteLine(ex.Message); } } Any ideas how can I work around?

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  • [java] Efficiency of while(true) ServerSocket Listen

    - by Submerged
    I am wondering if a typical while(true) ServerSocket listen loop takes an entire core to wait and accept a client connection (Even when implementing runnable and using Thread .start()) I am implementing a type of distributed computing cluster and each computer needs every core it has for computation. A Master node needs to communicate with these computers (invoking static methods that modify the algorithm's functioning). The reason I need to use sockets is due to the cross platform / cross language capabilities. In some cases, PHP will be invoking these java static methods. I used a java profiler (YourKit) and I can see my running ServerSocket listen thread and it never sleeps and it's always running. Is there a better approach to do what I want? Or, will the performance hit be negligible? Please, feel free to offer any suggestion if you can think of a better way (I've tried RMI, but it isn't supported cross-language. Thanks everyone

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  • SQLAuthority News – Windows Azure Training Kit Updated October 2012

    - by pinaldave
    Microsoft has recently released the updated to Windows Azure Training Kit. Earlier this month they have updated the kit and included quite a lot of things. Now the training kit contains 47 hands-on labs, 24 demos and 38 presentations. The best part is that the kit is now available to download in two different formats 1) Full Package (324.5 MB) and 2) Web Installer (2.4 MB). The full package enables you to download all of the hands-on labs and presentations to your local machine. The Web Installer allows you to select and download just the specific hands-on labs and presentations that you need. This Windows Azure Training Kit contains Hands on Labs, Presentations and Videos and Demos. I encourage all of you to try this out as well. The Kit also contains details about Samples and Tools. The training kit is the most authoritative learning resource on Windows Azure. You can download the Windows Azure Training Kit from here. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Azure, SQL Download, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Are there any resources on how to identify problems that could best be solved with templates?

    - by sap
    I decided to improve my knowledge in template meta-programming. I know the syntax and rules and been playing with counteless examples from online resources. I understand how powerful templates can be and how much compile time optimization they can provide but I still cant "think in templates", I can't seem to know by myself if a certain problem could be best solved with templates and if it can, how to adapt that problem to templates. Is there some kind of online resource or book that teaches how to identify problems that could best be solved with templates and how to adapt that problem?

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  • C# Generic Arrays and math operations on it

    - by msedi
    Hello, I'm currently involved in a project where I have very large image volumes. This volumes have to processed very fast (adding, subtracting, thresholding, and so on). Additionally most of the volume are so large that they event don't fit into the memory of the system. For that reason I have created an abstract volume class (VoxelVolume) that host the volume and image data and overloads the operators so that it's possible to perform the regular mathematical operations on volumes. Thereby two more questions opened up which I will put into stackoverflow into two additional threads. Here is my first question. My volume is implemented in a way that it only can contain float array data, but most of the containing data is from an UInt16 image source. Only operations on the volume can create float array images. When I started implementing such a volume the class looked like following: public abstract class VoxelVolume<T> { ... } but then I realized that overloading the operators or return values would get more complicated. An example would be: public abstract class VoxelVolume<T> { ... public static VoxelVolume<T> Import<T>(param string[] files) { } } also adding two overloading operators would be more complicated: ... public static VoxelVolume<T> operator+(VoxelVolume<T> A, VoxelVolume<T> B) { ... } Let's assume I can overcome the problems described above, nevertheless I have different types of arrays that contain the image data. Since I have fixed my type in the volumes to float the is no problem and I can do an unsafe operation when adding the contents of two image volume arrays. I have read a few threads here and had a look around the web, but found no real good explanation of what to do when I want to add two arrays of different types in a fast way. Unfortunately every math operation on generics is not possible, since C# is not able to calculate the size of the underlying data type. Of course there might by a way around this problem by using C++/CLR, but currently everything I have done so far, runs in 32bit and 64bit without having to do a thing. Switching to C++/CLR seemed to me (pleased correct me if I'm wrong) that I'm bound to a certain platform (32bit) and I have to compile two assemblies when I let the application run on another platform (64bit). Is this true? So asked shortly: How is it possible to add two arrays of two different types in a fast way. Is it true that the developers of C# haven't thought about this. Switching to a different language (C# - C++) seems not to be an option. I realize that simply performing this operation float []A = new float[]{1,2,3}; byte []B = new byte[]{1,2,3}; float []C = A+B; is not possible and unnecessary although it would be nice if it would work. My solution I was trying was following: public static class ArrayExt { public static unsafe TResult[] Add<T1, T2, TResult>(T1 []A, T2 []B) { // Assume the length of both arrays is equal TResult[] result = new TResult[A.Length]; GCHandle h1 = GCHandle.Alloc (A, Pinned); GCHandle h2 = GCHandle.Alloc (B, Pinned); GCHandle hR = GCHandle.Alloc (C, Pinned); void *ptrA = h1.ToPointer(); void *ptrB = h2.ToPointer(); void *ptrR = hR.ToPointer(); for (int i=0; i<A.Length; i++) { *((TResult *)ptrR) = (TResult *)((T1)*ptrA + (T2)*ptrB)); } h1.Free(); h2.Free(); hR.Free(); return result; } } Please excuse if the code above is not quite correct, I wrote it without using an C# editor. Is such a solution a shown above thinkable? Please feel free to ask if I made a mistake or described some things incompletely. Thanks for your help Martin

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  • How do game programmers design their classes to reuse in AI, network and play and pass mode?

    - by Amogh Talpallikar
    For a two player game where, your opponent could be on the network, CPU itself or near you where you would play turn by turn on the same machine. How do people design classes for re-use ? I am in a similar situation and have no experience in making such complex games. But here is what I have thought, If I am a player object , I should only be interacting with the GameManager or GameEngine Singleton , from which I will get various notifications about the game status. I dont care where and who my opponent is, this GameManager depending upon the game mode, will interact with gameNetworkManager , or AI tell me what the opponent played. I am not sure about the scenario where we play and pass [turn by turn on same machine]. Hoping for a brief but clear explanation or at least a link to a similar resource.:)

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  • How can I limit access to a particular class to one caller at a time in an ASMX web service?

    - by MusiGenesis
    I have a web service method in which I create a particular type of object, use it for a few seconds, and then dispose it. Because of problems arising from multiple threads creating and using instances of this class at the same time, I need to restrict the method so that only one caller at a time ever has one of these objects. To do this, I am creating a private static object: private static object _lock = new object(); ... and then inside the web service method I do this around the critical code: lock (_lock) { using (DangerousObject do = new DangerousObject()) { do.MakeABigMess(); do.CleanItUp(); } } I'm not sure this is working, though. Do I have this right? Will this code ensure that only one instance of DangerousObject is instantiated and in use at a time? Or does each caller get their own copy of _lock, rendering my code here laughable?

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  • Help Understanding Function

    - by Fred F.
    What does the following function perform? public static double CleanAngle(double angle) { while (angle < 0) angle += 2 * System.Math.PI; while (angle > 2 * System.Math.PI) angle -= 2 * System.Math.PI; return angle; } This is how it is used with ATan2. I believe the actually values passed to ATan2 are always positive. static void Main(string[] args) { int q = 1; //'x- and y-coordinates will always be positive values //'therefore, do i need to "clean"? foreach (Point oPoint in new Point[] { new Point(8,20), new Point(-8,20), new Point(8,-20), new Point(-8,-20)}) { Debug.WriteLine(Math.Atan2(oPoint.Y, oPoint.X), "unclean " + q.ToString()); Debug.WriteLine(CleanAngle(Math.Atan2(oPoint.Y, oPoint.X)), "cleaned " + q.ToString()); q++; } //'output //'unclean 1: 1.19028994968253 //'cleaned 1: 1.19028994968253 //'unclean 2: 1.95130270390726 //'cleaned 2: 1.95130270390726 //'unclean 3: -1.19028994968253 //'cleaned 3: 5.09289535749705 //'unclean 4: -1.95130270390726 //'cleaned 4: 4.33188260327232 }

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  • Enclosing service execution in try-catch: bad practice?

    - by Sorin Comanescu
    Hi, Below is the usual Program.cs content for a windows service program: static class Program { /// <summary> /// The main entry point for the application. /// </summary> static void Main() { ServiceBase[] ServicesToRun; ServicesToRun = new ServiceBase[] { new MyService() }; ServiceBase.Run(ServicesToRun); } } Is it a bad practice to enclose the ServiceBase.Run(...) in a try-catch block? Thanks.

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  • Use MD5 to validate the exchanged files between Oracle and Customer

    - by Jie Chen
    Oracle Supports may ask customers to upload some data files (Database Dump, Trace Log, etc) for research. We often see the scenario that the uploaded huge files are corrupted and have to ask to re-upload. Then we may waste much time during this period. To avoid this, customers can tell Support the MD5 checksum of the upload files, requesting support to validate same if they have gotten the correct file in good format. MD5 on Linux We can use "md5sum" command directly. For example we calculate the file PrintManager.class MD5 checksum value. [jijichen@jclinux temp]$ md5sum PrintManager.class e0bf8c7623240ccd15ee17c0478427a1 PrintManager.class MD5 on Windows There are many freeware to calculate MD5 on internet. For example we can use WinMD5Free tool. You can download it from here. http://www.winmd5.com https://blogs.oracle.com/jiechen/resource/2013/winmd5free.zip

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  • Abstract Factory Using Generics: Is Explicitly Converting a Specified Type to Generic a Bad Practice

    - by Merritt
    The question's title says it all. I like how it fits into the rest of my code, but does it smell? public interface IFoo<T> { T Bar { get; set; } } public class StringFoo : IFoo<string> { public string Bar { get; set; } } public static class FooFactory { public static IFoo<T> CreateFoo<T>() { if (typeof(T) == typeof(string)) { return new StringFoo() as IFoo<T>; } throw new NotImplementedException(); } } UPDATE: this is sort of a duplicate of Is the StaticFactory in codecampserver a well known pattern?

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  • Saving a reference to a int.

    - by Scott Chamberlain
    Here is a much simplified version of what I am trying to do static void Main(string[] args) { int test = 0; int test2 = 0; Test A = new Test(ref test); Test B = new Test(ref test); Test C = new Test(ref test2); A.write(); //Writes 1 should write 1 B.write(); //Writes 1 should write 2 C.write(); //Writes 1 should write 1 Console.ReadLine(); } class Test { int _a; public Test(ref int a) { _a = a; //I loose the reference here } public void write() { var b = System.Threading.Interlocked.Increment(ref _a); Console.WriteLine(b); } } In my real code I have a int that will be incremented by many threads however where the threads a called it will not be easy to pass it the parameter that points it at the int(In the real code this is happening inside a IEnumerator). So a requirement is the reference must be made in the constructor. Also not all threads will be pointing at the same single base int so I can not use a global static int either. I know I can just box the int inside a class and pass the class around but I wanted to know if that is the correct way of doing something like this? What I think could be the correct way: static void Main(string[] args) { Holder holder = new Holder(0); Holder holder2 = new Holder(0); Test A = new Test(holder); Test B = new Test(holder); Test C = new Test(holder2); A.write(); //Writes 1 should write 1 B.write(); //Writes 2 should write 2 C.write(); //Writes 1 should write 1 Console.ReadLine(); } class Holder { public Holder(int i) { num = i; } public int num; } class Test { Holder _holder; public Test(Holder holder) { _holder = holder; } public void write() { var b = System.Threading.Interlocked.Increment(ref _holder.num); Console.WriteLine(b); } } Is there a better way than this?

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  • Recording Available: March 2010 Quarterly Customer Update Webcast

    - by michelle.huff
    Missed the last Quarterly Customer Update Webcast? We discussed several product updates on the March quarterly customer Webcast, including the first phase of the Oracle Content Management 11g release. Some of the highlights include Information Rights Management (IRM) 11g and Imaging and Process Management (I/PM) 11g Overviews. Additionally, we covered I/PM 11g new features, implementation and migration topics that existing customers would like to know. You can find quick links to all the resources I mentioned on the call, as well as links to the presentation and recording details in My Oracle Support from the March 2010 Webcast Resource Links page on OTN.

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