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  • C# Different class objects in one list

    - by jeah_wicer
    I have looked around some now to find a solution to this problem. I found several ways that could solve it but to be honest I didn't realize which of the ways that would be considered the "right" C# or OOP way of solving it. My goal is not only to solve the problems but also to develop a good set of code standards and I'm fairly sure there's a standard way to handle this problem. Let's say I have 2 types of printer hardwares with their respective classes and ways of communicating: PrinterType1, PrinterType2. I would also like to be able to later on add another type if neccessary. One step up in abstraction those have much in common. It should be possible to send a string to each one of them as an example. They both have variables in common and variables unique to each class. (One for instance communicates via COM-port and has such an object, while the other one communicates via TCP and has such an object). I would however like to just implement a List of all those printers and be able to go through the list and perform things as "Send(string message)" on all Printers regardless of type. I would also like to access variables like "PrinterList[0].Name" that are the same for both objects, however I would also at some places like to access data that is specific to the object itself (For instance in the settings window of the application where the COM-port name is set for one object and the IP/port number for another). So, in short something like: In common: Name Send() Specific to PrinterType1: Port Specific to PrinterType2: IP And I wish to, for instance, do Send() on all objects regardless of type and the number of objects present. I've read about polymorphism, Generics, interfaces and such, but I would like to know how this, in my eyes basic, problem typically would be dealt with in C# (and/or OOP in general). I actually did try to make a base class, but it didn't quite seem right to me. For instance I have no use of a "string Send(string Message)" function in the base class itself. So why would I define one there that needs to be overridden in the derived classes when I would never use the function in the base class ever in the first place? I'm really thankful for any answers. People around here seem very knowledgeable and this place has provided me with many solutions earlier. Now I finally have an account to answer and vote with too. EDIT: To additionally explain, I would also like to be able to access the objects of the actual printertype. For instance the Port variable in PrinterType1 which is a SerialPort object. I would like to access it like: PrinterList[0].Port.Open() and have access to the full range of functionality of the underlaying port. At the same time I would like to call generic functions that work in the same way for the different objects (but with different implementations): foreach (printer in Printers) printer.Send(message)

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  • Correct usage of "<T extends SuperClass>"

    - by yusaku
    I am not familiar with "Generics". Is it a correct use of "<T extends SuperClass>" ? And do you agree that the codes after using generics are better? Before using Generics ================================================= public abstract class SuperSample { public void getSomething(boolean isProcessA) { doProcessX(); if(isProcessA){ doProcessY(new SubASample()); }else{ doProcessY(new SubBSample()); } } protected abstract void doProcessX(); protected void doProcessY(SubASample subASample) { // Nothing to do } protected void doProcessY(SubBSample subBSample) { // Nothing to do } } public class SubASample extends SuperSample { @Override protected void doProcessX() { System.out.println("doProcessX in SubASample"); } @Override protected void doProcessY(SubASample subASample) { System.out.println("doProcessY in SubASample"); } } public class Sample { public static void main(String[] args) { SubASample subASample = new SubASample(); subASample.getSomething(true); } } After using Generics ================================================= public abstract class SuperSample { public void getSomething(boolean isProcessA) { doProcessX(); if(isProcessA){ doProcessY(new SubASample()); }else{ doProcessY(new SubBSample()); } } protected abstract void doProcessX(); protected abstract <T extends SuperSample> void doProcessY(T subSample); } public class SubASample extends SuperSample { @Override protected void doProcessX() { System.out.println("doProcessX in SubASample"); } @Override protected <T extends SuperSample> void doProcessY(T subSample) { System.out.println("doProcessY in SubASample"); } } public class Sample { public static void main(String[] args) { SubASample subASample = new SubASample(); subASample.getSomething(true); } }

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  • Professional way to write project documentation

    - by EugeneP
    What tools and standards do you use to describe your project, database, modules, classes, their interaction for programmers, let's say after the project is finished. Do you use UML? Are there enterprise standards for Java developers, how to write such a documentation let's say from SUN? Are there specific tools that simplify this documentation process & compilation of neccessary docs. If there are good books on project documenting process, please give me links to Amazon.

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  • How can I add imports to an "eval"ed piece of clojure code?

    - by Zubair
    I would like to evaluate some clojure code entered by users interactively, and I would like to "use" certain namespaces and "import" certain Java classes as well. I end up running the code using: (defn execute-command [string-command] let [ code-with-context (add-code-context string-command) result (eval(read-string code-with-context)) ] result ) My question is how can I program "add-code-context" to add the required context to the code in "string-command"?

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  • Why doesn't String's hashCode() cache 0?

    - by polygenelubricants
    I noticed in the Java 6 source code for String that hashCode only caches values other than 0. The difference in performance is exhibited by the following snippet: public class Main{ static void test(String s) { long start = System.currentTimeMillis(); for (int i = 0; i < 10000000; i++) { s.hashCode(); } System.out.format("Took %d ms.%n", System.currentTimeMillis() - start); } public static void main(String[] args) { String z = "Allocator redistricts; strict allocator redistricts strictly."; test(z); test(z.toUpperCase()); } } Running this in ideone.com gives the following output: Took 1470 ms. Took 58 ms. So my questions are: Why doesn't String's hashCode() cache 0? What is the probability that a Java string hashes to 0? What's the best way to avoid the performance penalty of recomputing the hash value every time for strings that hash to 0? Is this the best-practice way of caching values? (i.e. cache all except one?) For your amusement, each line here is a string that hash to 0: pollinating sandboxes amusement & hemophilias schoolworks = perversive electrolysissweeteners.net constitutionalunstableness.net grinnerslaphappier.org BLEACHINGFEMININELY.NET WWW.BUMRACEGOERS.ORG WWW.RACCOONPRUDENTIALS.NET Microcomputers: the unredeemed lollipop... Incentively, my dear, I don't tessellate a derangement. A person who never yodelled an apology, never preened vocalizing transsexuals.

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  • Restrict the class of an association in a Hibernate Criteria query

    - by D Lawson
    I have an object, 'Response' that has a property called 'submitter'. Submitters can be one of several different classes including Student, Teacher, etc... I would like to be able to execute a criteria query where I select only responses submitted by teachers - so this means putting a class restriction on an associated entity. Any ideas on this? I'd like to stay away from direct SQL or HQL.

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  • Make instance of class in java at runtime

    - by Milan
    In my program I generate classes dynamically but when I try: Class service = Class.forName("com.MyClass"); I recieve java.lang.ClassNotFoundException If I run one more time the program (in Eclipse), then it is working. Does anybody see the problem

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  • Named Range Breaks Code

    - by Daniel
    I have one workbook with several sheets. I populate the listboxes (pulling static data from cells) on the 2nd sheet, click a button and it runs fine. When I populate the listboxes with a named range, the listbox populates the way I want, but I get an error because the code thinks that I didn't select anything in the listbox, even though I did. So it passes through "" instead of "title". Is this a common issue? The named range isn't a problem because it passes through the data to the listbox and I know it's selecting data because as soon as the listbox loses focus, it spits out the contents of the cell into cell A1. What's even stranger is that I have the contents of the listbox set to Msg1. So A1 gets populated with Msg1 (what I actually selected in the listbox). But when I try and use Msg1 in the code, it tells me that Msg1 is "". Again, this only happens when I use the dynamic named range, not with static data in cells K1:K9. Private Function strEndSQL1 As String Dim strSQL As String strSQL = "" 'Create SQL statement strSQL = "FROM (SELECT * FROM dbo.Filter WHERE ID = " & TextBox1.Text & " And Source IN (" & Msg1 & ")) a FULL OUTER JOIN " strSQL = strSQL & "(SELECT * FROM dbo.Filters WHERE ID = " & TextBox2.Text & " And Source IN (" & Msg1 & ")) b " strSQL = strSQL & "ON a.Group = b.Group strEndSQL = strSQL End Function

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  • PayPal recurring payments in .net

    - by jiwan
    Hi Every One, I'm thinking about making a subscription system. The samples on the website I found to be difficult to follow because they are separated classes for very specific issues. From what I understand (if I'm not wrong) the PayPal Recurring is the best choice for subscription system. However I hope that you can help me to find a complete sample about PayPal Recurring using .NET.

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  • Global name not defined error in Django/Python trying to set foreignkey

    - by Mark
    Summary: I define a method createPage within a file called PageTree.py that takes a Source model object and a string. The method tries to generate a Page model object. It tries to set the Page model object's foreignkey to refer to the Source model object which was passed in. This throws a NameError exception! I'm trying to represent a website which is structured like a tree. I define the Django models Page and Source, Page representing a node on the tree and Source representing the contents of the page. (You can probably skip over these, this is a basic tree implementation using doubly linked nodes). class Page(models.Model): name = models.CharField(max_length=50) parent = models.ForeignKey("self", related_name="children", null=True); firstChild = models.ForeignKey("self", related_name="origin", null=True); nextSibling = models.ForeignKey("self", related_name="prevSibling", null=True); previousSibling = models.ForeignKey("self", related_name="nxtSibling", null=True); source = models.ForeignKey("Source"); class Source(models.Model): #A source that is non dynamic will be refered to as a static source #Dynamic sources contain locations that are names of functions #Static sources contain locations that are places on disk name = models.CharField(primary_key=True, max_length=50) isDynamic = models.BooleanField() location = models.CharField(max_length=100); I've coded a python program called PageTree.py which allows me to request nodes from the database and manipulate the structure of the tree. Here is the trouble making method: def createPage(pageSource, pageName): page = Page() page.source = pageSource page.name = pageName page.save() return page I'm running this program in a shell through manage.py in Windows 7 manage.py shell from mysite.PageManager.models import Page, Source from mysite.PageManager.PageTree import * ... create someSource = Source(), populate the fields, and save it ... createPage(someSource, "test") ... NameError: global name 'source' is not defined When I type in the function definition for createPage into the shell by hand, the call works without error. This is driving me bonkers and help is appreciated.

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  • Purpose of singletons in programming

    - by thecoshman
    This is admittedly a rather loose question. My current understanding of singletons is that they are a class that you set up in such a way that only one instance is ever created. This sounds a lot like a static class to me. The main differnce being that with a static class you don't / can't instance it, you just use it such as Math.pi(). With a singletong class, you would still need to do something like singleton mySingleton = new singleton(); mysingleton.set_name("foo"); singleton otherSingleton = new singleton(); // correct me if i am wrong, but mysingleton == othersingleton right now, yes? // this the following should happen? otherSingleston.set_name("bar"); mysingleton.report_name(); // will output "bar" won't it? Please note, I am asking this language independently, more about the concept. So I am not so worried about actually how to coed such a class, but more why you would wan't to and what thing you would need to consider.

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  • Why aren't my threads start at the same time? Java

    - by Ada
    Hi, I have variable number of threads which are used for parallel downloading. I used this, for(int i = 0; i< sth; i++){ thrList.add(new myThread (parameters)); thrList.get(i).start(); thrList.get(i).join(); } I don't know why but they wait for each other to complete. When using threads, I am supposed get mixed print outs, since right then there are several threads running that code. However, when I print them out, they are always in order and one thread waits for the previous one to finish first. I only want them to join the main thread, not wait for each other. I noticed that when I measured time while downloading in parallel. How can I fix this? Why are they doing it in order? In my .java, there is MyThread class with run and there is Downloader class with static methods and variables. Would they be the cause of this? The static methods and variables? How can I fix this problem?

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  • auto-document exceptions on methods in C#/.NET

    - by Sarah Vessels
    I would like some tool, preferably one that plugs into VS 2008/2010, that will go through my methods and add XML comments about the possible exceptions they can throw. I don't want the <summary> or other XML tags to be generated for me because I'll fill those out myself, but it would be nice if even on private/protected methods I could see which exceptions could be thrown. Otherwise I find myself going through the methods and hovering on all the method calls within them to see the list of exceptions, then updating that method's <exception list to include those. Maybe a VS macro could do this? From this: private static string getConfigFilePath() { return Path.Combine(Environment.CurrentDirectory, CONFIG_FILE); } To this: /// <exception cref="System.ArgumentException"/> /// <exception cref="System.ArgumentNullException"/> /// <exception cref="System.IO.IOException"/> /// <exception cref="System.IO.DirectoryNotFoundException"/> /// <exception cref="System.Security.SecurityException"/> private static string getConfigFilePath() { return Path.Combine(Environment.CurrentDirectory, CONFIG_FILE); } Update: it seems like the tool would have to go through the methods recursively, e.g., method1 calls method2 which calls method3 which is documented as throwing NullReferenceException, so both method2 and method1 are documented by the tool as also throwing NullReferenceException. The tool would also need to eliminate duplicates, like if two calls within a method are documented as throwing DirectoryNotFoundException, the method would only list <exception cref="System.IO.DirectoryNotFoundException"/> once.

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  • How can I serve up color-coded Java code using PHP?

    - by Eric
    I'd like to embed code from my SVN repository into my website, using PHP. The SVN has public anonymous access, so the PHP code should be fine reading it. The code on said SVN is java, and so far I've had no luck finding a syntax-highlighter to make the code more readable. Ideally I'd like one that uses CSS classes so that I can change the colors to match the look of the website. Could someone point me to a PHP library that highlights Java code?

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  • Can Django be used for web services?

    - by alex
    My friend said, "Pylons is so much better for web services." My other friend said, "You can modify Django in a way to do exactly whatever you like." In Django, what is necessary to be modified (urls.py? models classes? settings?) in order to do "web services" with APIs and REST and versioning, etc etc.?

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  • C++ - Is it possible to implement memory leak testing in a unit test?

    - by sevaxx
    I'm trying to implement unit testing for my code and I'm having a hard time doing it. Ideally I would like to test some classes not only for good functionality but also for proper memory allocation/deallocation. I wonder if this check can be done using a unit testing framework. I am using Visual Assert btw. I would love to see some sample code , if possible !

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  • organizing unit test

    - by soulmerge
    I have found several conventions to housekeeping unit tests in a project and I'm not sure which approach would be suitable for our next PHP project. I am trying to find the best convention to encourage easy development and accessibility of the tests when reviewing the source code. I would be very interested in your experience/opinion regarding each: One folder for productive code, another for unit tests: This separates unit tests from the logic files of the project. This separation of concerns is as much a nuisance as it is an advantage: Someone looking into the source code of the project will - so I suppose - either browse the implementation or the unit tests (or more commonly: the implementation only). The advantage of unit tests being another viewpoint to your classes is lost - those two viewpoints are just too far apart IMO. Annotated test methods: Any modern unit testing framework I know allows developers to create dedicated test methods, annotating them (@test) and embedding them in the project code. The big drawback I see here is that the project files get cluttered. Even if these methods are separated using a comment header (like UNIT TESTS below this line) it just bloats the class unnecessarily. Test files within the same folders as the implementation files: Our file naming convention dictates that PHP files containing classes (one class per file) should end with .class.php. I could imagine that putting unit tests regarding a class file into another one ending on .test.php would render the tests much more present to other developers without tainting the class. Although it bloats the project folders, instead of the implementation files, this is my favorite so far, but I have my doubts: I would think others have come up with this already, and discarded this option for some reason (i.e. I have not seen a java project with the files Foo.java and FooTest.java within the same folder.) Maybe it's because java developers make heavier use of IDEs that allow them easier access to the tests, whereas in PHP no big editors have emerged (like eclipse for java) - many devs I know use vim/emacs or similar editors with little support for PHP development per se. What is your experience with any of these unit test placements? Do you have another convention I haven't listed here? Or am I just overrating unit test accessibility to reviewing developers?

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  • how to use cpp source for 2 projects

    - by joels
    I'm not sure if I am going about this the right way. I am making some c++ classes to use in 2 apps. I am going to have to compile them to be used in a Cocoa app and later be compiled for use with fastcgi. Should I create a dynamic library?

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  • C# some sort of plugin system

    - by nLL
    Hi, I am a mobile web developer and trying to monetize my traffic with mobile ad services and i have a problem. First of all to get most of out of your ads you usually need to do server side request to advert company's servers and there are quite few ad services. Problem starts when you want to use them in one site. All have different approaches to server side calls and trying to maintain and implement those ad codes becomes pain after a while. So I decided to write a class system where i can simply create methods for every company and upload it to my site. So far i have public Advert class public AdPublisher class with GetAd method that returns an Advert public Adservice class that has Service names as enum I also have converted server request codes of all ad services i use to classes. It works ok but I want to be able to create an ad service class upload it so that asp.net app can import/recognize it automatically like a plugin system. As I am new to .net I have no idea where to start or how to do it. To make thing clear here are my classes namespace Mobile.Publisher { public class AdPublisher { public AdPublisher() { IsTest = false; } public bool IsTest { get; set; } public HttpRequest CurrentVisitorRequestInfo { get; set; } public Advert GetAd(AdService service) { Advert returnAd = new Advert(); returnAd.Success = true; if (this.CurrentVisitorRequestInfo == null) { throw new Exception("CurrentVisitorRequestInfo for AdPublisher not set!"); } if (service == null) { throw new Exception("AdService not set!"); } if (service.ServiceName == AdServices.Admob) { returnAd.ReturnedAd = AdmobAds("000000"); } return returnAd; } } public enum AdServices { Admob, ServiceB, ServiceC } public class Advert { public bool Success { get; set; } public string ReturnedAd { get; set; } } public partial class AdService { public AdServices ServiceName { get; set; } public string PublisherOrSiteId { get; set; } public string ZoneOrChannelId { get; set; } } private string AdmobAds(string publisherid) { //snip return "test" } } Basically i want to be able to add another ad service and code like private string AdmobAds(string publisherid){ } So that it can be imported and recognised as ad service. I hope i was clear enough

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