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  • What software design pattern is best for the following scenario (C#)

    - by askjdh
    I have a gps device that records data e.g. datetime, latitude, longitude I have an sdk that reads the data from the device. The way the data is read: A command packet (basically a combination of int values in a struct) is sent to the device. The device responds with the data in fixed size chunks e.g. 64bytes Depending on the command issued I will get back differect data structs e.g. sending command 1 to the device returns a struct like struct x { id int, name char[20] } command 2 returns a collection of the following structs (basically it boils down to an array of the structs - y[12]) struct y { date datetime, lat decimal, lon decimal } I would then want to convert the struct to a class and save the data to a database. What would be the best way to encapsulate the entire process, preferably using some established design pattern? Many thanks M

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  • Where to store 3rd party libraries?

    - by zerkms
    I have asp.net mvc 2 application. Now I'm reimplementing it for working with Ninject. All is fine except one thing: where should I store Ninject.dll?? I've created lib directory inside my appdir and made reference to lib/Ninject.dll. But may be there are some general conventions on how to act in such cases?

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  • Single Responsibility Principle usage how can i call sub method correctly?

    - by Phsika
    i try to learn SOLID prencibles. i writed two type of code style. which one is : 1)Single Responsibility Principle_2.cs : if you look main program all instance generated from interface 1)Single Responsibility Principle_3.cs : if you look main program all instance genareted from normal class My question: which one is correct usage? which one can i prefer? namespace Single_Responsibility_Principle_2 { class Program { static void Main(string[] args) { IReportManager raporcu = new ReportManager(); IReport wordraporu = new WordRaporu(); raporcu.RaporHazirla(wordraporu, "data"); Console.ReadKey(); } } interface IReportManager { void RaporHazirla(IReport rapor, string bilgi); } class ReportManager : IReportManager { public void RaporHazirla(IReport rapor, string bilgi) { rapor.RaporYarat(bilgi); } } interface IReport { void RaporYarat(string bilgi); } class WordRaporu : IReport { public void RaporYarat(string bilgi) { Console.WriteLine("Word Raporu yaratildi:{0}",bilgi); } } class ExcellRaporu : IReport { public void RaporYarat(string bilgi) { Console.WriteLine("Excell raporu yaratildi:{0}",bilgi); } } class PdfRaporu : IReport { public void RaporYarat(string bilgi) { Console.WriteLine("pdf raporu yaratildi:{0}",bilgi); } } } Second 0ne all instance genareted from normal class namespace Single_Responsibility_Principle_3 { class Program { static void Main(string[] args) { WordRaporu word = new WordRaporu(); ReportManager manager = new ReportManager(); manager.RaporHazirla(word,"test"); } } interface IReportManager { void RaporHazirla(IReport rapor, string bilgi); } class ReportManager : IReportManager { public void RaporHazirla(IReport rapor, string bilgi) { rapor.RaporYarat(bilgi); } } interface IReport { void RaporYarat(string bilgi); } class WordRaporu : IReport { public void RaporYarat(string bilgi) { Console.WriteLine("Word Raporu yaratildi:{0}",bilgi); } } class ExcellRaporu : IReport { public void RaporYarat(string bilgi) { Console.WriteLine("Excell raporu yaratildi:{0}",bilgi); } } class PdfRaporu : IReport { public void RaporYarat(string bilgi) { Console.WriteLine("pdf raporu yaratildi:{0}",bilgi); } } }

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  • Procedures before checking in to source control?

    - by Mongus Pong
    I am starting to get a reputation at work as the "guy who breaks the builds". The problem is not that I am writing dodgy code, but when it comes to checking my fixes back into source control, it all goes wrong. I am regularly doing stupid things like : forgetting to add new files accidentally checking in code for a half fixed bug along with another bug fix forgetting to save the files in VS before checking them in I need to develop some habits / tools to stop this. What do you regularly do to ensure the code you check in is correct and is what needs to go in? Edit I forgot to mention that things can get pretty chaotic in this place. I quite often have two or three things that Im working on in the same code base at any one time. When I check in I will only really want to check in one of those things.

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  • Going from small to medium sized websites.

    - by Landitus
    I've been coding websites for a couple of years now, mostly in php and xhtml. I come from the design world, but I'm proud of doing standart compliant websites and great interfaces. Also used Wordpress and loved it. Most of the time there were really simple commercial websites, with no database included, where everything is done from scratch. Every page is parsed through an index?page=xxx and But I have a few prospects that are larger websites (let's call them 'medium sized websites') where I feel I'm lacking the following: How to dispach or render the pages (MVC controller instead of index?page=???) Proper page hierarchy and easy breadcrumbs implementation Auto generation of navigation menu, or an easy way to maintain them? Clean URLs Form validation Easy database support I really don't know if I should be looking into php scripts, and refine my skills or get into a CMS (like drupal) or a PHP framework. I found Wordpress very assuring and didn't feel trapped into crazy conventions, but I feel is not the right tool for this. I hate the CMS Page with the big textbox as I am used to code every page by hand my pages are not a title and a textbox. Got the feeling? My php skills are sort of medium/low still, but I would like to hear some thoughts of what I should learn to take the next step!

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  • Managing of shared resources between classes?

    - by Axarydax
    Imagine that I have a several Viewer component that are used for displaying text and they have few modes that user can switch (different font presets for viewing text/binary/hex). What would be the best approach for managing shared objects - for example fonts, find dialog, etc? I figured that static class with lazily initialized objects would be OK, but this might be the wrong idea. static class ViewerStatic { private static Font monospaceFont; public static Font MonospaceFont { get { if (monospaceFont == null) //TODO read font settings from configuration monospaceFont = new Font(FontFamily.GenericMonospace, 9, FontStyle.Bold); return monospaceFont; } } private static Font sansFont; public static Font SansFont { get { if (sansFont == null) //TODO read font settings from configuration sansFont = new Font(FontFamily.GenericSansSerif, 9, FontStyle.Bold); return sansFont; } } }

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  • How does a WCF server inform a WCF client about changes? (Better solution then simple polling, e.g.

    - by Ian Ringrose
    see also "WCF push to client through firewall" I need to have a WCF client that connect to a WCF server, then when some of the data changes on the server the clients need to update its display. As there is likely to be a firewall between the clients and the server. All communications must be over HTTP The server can not make an (physical) outgoing call to the client. As I am writing both the client and the server I do not need to limit the solution to only using soap etc. I am looking for built in surport for "long polling" / "Comet" etc Thanks for the most informative answer from Drew Marsh on how to implement long polling in WCF. However I thought the main “selling point” of WCF was that you could do this sort of thing just by configuring the channels to be used in the config file. E.g I want a channel that logically two way but physically incoming only.

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  • Showing response time in a rails app.

    - by anshul
    I want to display a This page took x seconds widget at the bottom of every page in my rails application. I would like x to reflect the approximate amount of time the request spent on my server. What is the usual way this is done in Rails?

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  • Good input validation loop using cin - C++

    - by Alex
    Hi there, I'm in my second OOP class, and my first class was taught in C#, so I'm new to C++ and currently I am practicing input validation using cin. So here's my question: Is this loop I constructed a pretty good way of validating input? Or is there a more common/accepted way of doing it? Thanks! Code: int taxableIncome; int error; // input validation loop do { error = 0; cout << "Please enter in your taxable income: "; cin >> taxableIncome; if (cin.fail()) { cout << "Please enter a valid integer" << endl; error = 1; cin.clear(); cin.ignore(80, '\n'); } }while(error == 1);

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  • Coding styles for html

    - by Hulk
    Hi, Please the coding standard followed for HTML .Please suggest links that the has the coding styles for html.(like Camel case or .....) <table> <tr> <td> Data </td> </tr> </table> Thanks..

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  • Should I throw my own ArgumentOutOfRangeException or let one bubble up from below?

    - by Neil N
    I have a class that wraps List< I have GetValue by index method: public RenderedImageInfo GetValue(int index) { list[index].LastRetrieved = DateTime.Now; return list[index]; } If the user requests an index that is out of range, this will throw an ArgumentOutOfRangeException . Should I just let this happen or check for it and throw my own? i.e. public RenderedImageInfo GetValue(int index) { if (index >= list.Count) { throw new ArgumentOutOfRangeException("index"); } list[index].LastRetrieved = DateTime.Now; return list[index]; } In the first scenario, the user would have an exception from the internal list, which breaks mt OOP goal of the user not needing to know about the underlying objects. But in the second scenario, I feel as though I am adding redundant code. Edit: And now that I think of it, what about a 3rd scenario, where I catch the internal exception, modify it, and rethrow it?

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  • Managing string resources in a Java application - singleton?

    - by Joe Attardi
    I seek a solution to the age-old problem of managing string resources. My current implementation seems to work well, but it depends on using singletons, and I know how often singletons can be maligned. The resource manager class has a singleton instance that handles lookups in the ResourceBundle, and you use it like so: MessageResources mr = MessageResources.getMessageResources(); // returns singleton instance ... JLabel helloLabel = new JLabel(mr.getString("label.hello")); Is this an appropriate use of a singleton? Is there some better, more universally used approach that I'm not aware of? I understand that this is probably a bit subjective, but any feedback I can get would be appreciated. I'd rather find out early on that I'm doing it wrong than later on in the process. Thanks!

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  • MVC Localization of Default Model Binder

    - by Dai Bok
    Hi, I am currently trying to figure out how to localize the error messages generated by MVC. Let me use the default model binder as an example, so I can explain the problem. Assuming I have a form, where a user enters thier age. The user then enters "ten" in to the form, but instead of getting the expected error of "Age must be beween 18 and 25." the message "The value 'ten' is not valid for Age." is displayed. The entity's age property is defined below: [Range(18, 25, ErrorMessageResourceType = typeof (Errors), ErrorMessageResourceName = "Age", ErrorMessage = "Range_ErrorMessage")] public int Age { get; set; } After some digging, I notice that this error text comes from the System.Web.Mvc.Resources.DefaultModelBinder_ValueInvalid in the MvcResources.resx file. Now, how can create localized versions of this file? As A solution, for example, should I download MVC source and add MvcResources.en_GB.resx, MvcResources.fr_FR.resx, MvcResources.es_ES.resx and MvcResources.de_DE.resx, and then compile my own version of MVC.dll? But I don't like this idea. Any one else know a better way?

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  • Best practice for installing python modules from an arbitrary VCS repository

    - by fmark
    I'm newish to the python ecosystem, and have a question about module editing. I use a bunch of third-party modules, distributed on PyPi. Coming from a C and Java background, I love the ease of easy_install <whatever>. This is a new, wonderful world, but the model breaks down when I want to edit the newly installed module for two reasons: The egg files may be stored in a folder or archive somewhere crazy on the file system. Using an egg seems to preclude using the version control system of the originating project, just as using a debian package precludes development from an originating VCS repository. What is the best practice for installing modules from an arbitrary VCS repository? I want to be able to continue to import foomodule in other scripts.

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  • Java: Is clone() really ever used? What about defensive copying in getters/setters?

    - by GreenieMeanie
    Do people practically ever use defensive getters/setters? To me, 99% of the time you intend for the object you set in another object to be a copy of the same object reference, and you intend for changes you make to it to also be made in the object it was set in. If you setDate(Date dt) and modify dt later, who cares? Unless I want some basic immutable data bean that just has primitives and maybe something simple like a Date, I never use it. As far as clone, there are issues as to how deep or shallow the copy is, so it seems kind of "dangerous" to know what is going to come out when you clone an Object. I think I have only used clone() once or twice, and that was to copy the current state of the object because another thread (ie another HTTP request accessing the same object in Session) could be modifying it. Edit - A comment I made below is more the question: But then again, you DID change the Date, so it's kind of your own fault, hence whole discussion of term "defensive". If it is all application code under your own control among a small to medium group of developers, will just documenting your classes suffice as an alternative to making object copies? Or is this not necessary, since you should always assume something ISN'T copied when calling a setter/getter?

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  • What's the most unsound program you've had to maintain?

    - by Robert Rossney
    I periodically am called upon to do maintenance work on a system that was built by a real rocket surgeon. There's so much wrong with it that it's hard to know where to start. No, wait, I'll start at the beginning: in the early days of the project, the designer was told that the system would need to scale, and he'd read that a source of scalability problems was traffic between the application and database servers, so he made sure to minimize this traffic. How? By putting all of the application logic in SQL Server stored procedures. Seriously. The great bulk of the application functions by the HTML front end formulating XML messages. When the middle tier receives an XML message, it uses the document element's tag name as the name of the stored procedure it should call, and calls the SP, passing it the entire XML message as a parameter. It takes the XML message that the SP returns and returns it directly back to the front end. There is no other logic in the application tier. (There was some code in the middle tier to validate the incoming XML messages against a library of schemas. But I removed it, after ascertaining that 1) only a small handful of messages had corresponding schemas, 2) the messages didn't actually conform to these schemas, and 3) after validating the messages, if any errors were encountered, the method discarded them. "This fuse box is a real time-saver - it comes from the factory with pennies pre-installed!") I've seen software that does the wrong thing before. Lots of it. I've written quite a bit. But I've never seen anything like the steely-eyed determination to do the wrong thing, at every possible turn, that's embodied in the design and programming of this system. Well, at least he went with what he knew, right? Um. Apparently, what he knew was Access. And he didn't really understand Access. Or databases. Here's a common pattern in this code: SELECT @TestCodeID FROM TestCode WHERE TestCode = @TestCode SELECT @CountryID FROM Country WHERE CountryAbbr = @CountryAbbr SELECT Invoice.*, TestCode.*, Country.* FROM Invoice JOIN TestCode ON Invoice.TestCodeID = TestCode.ID JOIN Country ON Invoice.CountryID = Country.ID WHERE Invoice.TestCodeID = @TestCodeID AND Invoice.CountryID = @CountryID Okay, fine. You don't trust the query optimizer either. But how about this? (Originally, I was going to post this in What's the best comment in source code you have ever encountered? but I realized that there was so much more to write about than just this one comment, and things just got out of hand.) At the end of many of the utility stored procedures, you'll see code that looks like the following: -- Fix NULLs SET @TargetValue = ISNULL(@TargetValue, -9999) Yes, that code is doing exactly what you can't allow yourself to believe it's doing lest you be driven mad. If the variable contains a NULL, he's alerting the caller by changing its value to -9999. Here's how this number is commonly used: -- Get target value EXEC ap_GetTargetValue @Param1, @Param2, OUTPUT @TargetValue -- Check target value for NULL value IF @TargetValue = -9999 ... Really. For another dimension of this system, see the article on thedailywtf.com entitled I Think I'll Call Them "Transactions". I'm not making any of this up. I swear. I'm often reminded, when I work on this system, of Wolfgang Pauli's famous response to a student: "That isn't right. It isn't even wrong." This can't really be the very worst program ever. It's definitely the worst one I've worked

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  • Is it good practice to call module functions directly in VB.NET?

    - by froadie
    I have a Util module in my VB.NET program that has project-wide methods such as logging and property parsing. The general practice where I work seems to be to call these methods directly without prefixing them with Util. When I was new to VB, it took me a while to figure out where these methods/functions were coming from. As I use my own Util methods now, I can't help thinking that it's a lot clearer and more understandable to add Util. before each method call (you know immediately that it's user-defined but not within the current class, and where to find it), and is hardly even longer. What's the general practice when calling procedures/functions of VB modules? Should we prefix them with the module name or not?

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  • Design Question on when to save

    - by Ben
    Hi, I was just after peoples opinion on when the best time to save an object (or collection of objects) is. I appreciate that it can be completely dependent on the situation that you are in but here is my situation. I have a collection of objects "MyCollection" in a grid. You can open each object "MyObject" in an editor dialogue by double clicking on the grid. Selecting "Cancel" on the dialogue will back out any changes you have made, but should selecting "ok" commit those changes back to the database, or should they commit the changes on that object back to the collection and have a save method that iterates through the collection and saves all changed objects? If i have an object "MyParentObject", that contains a collection of childen "MyChildObjectCollection", none of the changes made to each "MyChildObject" would be commited to the database until the "MyParentObject" was saved - this makes sense. However in my current situation, none of the objects in the collection are linked, therefore should the "Ok" on the dialogue commit the changes to the database? Appreciate any opinions on this. Thanks

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  • Design question what pattern to use

    - by rahul
    Problem Description: We have a requirement of storing the snapshot of an entity temporarily in the database untill a certain period of time untill all the processes to approve the data are completed. Once all approvals are completed the data shall be permanantly persisted into the actual table. Example: 1) Consider an entity called "User". One way to create the user is through the "Create Account Process". 2) The "Create Account Process" shall capture all the information of the User and store it in a temporary table in the database. 3) The data shall be used by the "Account Approval Process" to run its verification process. 4. After all the verification is completed successfully, the User data shall be persisted to the actual table. Question: Where to store the user data entered during "Create Account Process". Additionally, User data should be editable till the verification process is complete.

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  • Best Practice - Removing item from generic collection in C#

    - by Matt Davis
    I'm using C# in Visual Studio 2008 with .NET 3.5. I have a generic dictionary that maps types of events to a generic list of subscribers. A subscriber can be subscribed to more than one event. private static Dictionary<EventType, List<ISubscriber>> _subscriptions; To remove a subscriber from the subscription list, I can use either of these two options. Option 1: ISubscriber subscriber; // defined elsewhere foreach (EventType event in _subscriptions.Keys) { if (_subscriptions[event].Contains(subscriber)) { _subscriptions[event].Remove(subscriber); } } Option 2: ISubscriber subscriber; // defined elsewhere foreach (EventType event in _subscriptions.Keys) { _subscriptions[event].Remove(subscriber); } I have two questions. First, notice that Option 1 checks for existence before removing the item, while Option 2 uses a brute force removal since Remove() does not throw an exception. Of these two, which is the preferred, "best-practice" way to do this? Second, is there another, "cleaner," more elegant way to do this, perhaps with a lambda expression or using a LINQ extension? I'm still getting acclimated to these two features. Thanks. EDIT Just to clarify, I realize that the choice between Options 1 and 2 is a choice of speed (Option 2) versus maintainability (Option 1). In this particular case, I'm not necessarily trying to optimize the code, although that is certainly a worthy consideration. What I'm trying to understand is if there is a generally well-established practice for doing this. If not, which option would you use in your own code?

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  • Design pattern for cost calculator app?

    - by Anders Svensson
    Hi, I have a problem that I’ve tried to get help for before, but I wasn’t able to solve it then, so I’m trying to simplify the problem now to see if I can get some more concrete help with this because it is driving me crazy… Basically, I have a working (more complex) version of this application, which is a project cost calculator. But because I am at the same time trying to learn to design my applications better, I would like some input on how I could improve this design. Basically the main thing I want is input on the conditionals that (here) appear repeated in two places. The suggestions I got before was to use the strategy pattern or factory pattern. I also know about the Martin Fowler book with the suggestion to Refactor conditional with polymorphism. I understand that principle in his simpler example. But how can I do either of these things here (if any would be suitable)? The way I see it, the calculation is dependent on a couple of conditions: 1. What kind of service is it, writing or analysis? 2. Is the project small, medium or large? (Please note that there may be other parameters as well, equally different, such as “are the products new or previously existing?” So such parameters should be possible to add, but I tried to keep the example simple with only two parameters to be able to get concrete help) So refactoring with polymorphism would imply creating a number of subclasses, which I already have for the first condition (type of service), and should I really create more subclasses for the second condition as well (size)? What would that become, AnalysisSmall, AnalysisMedium, AnalysisLarge, WritingSmall, etc…??? No, I know that’s not good, I just don’t see how to work with that pattern anyway else? I see the same problem basically for the suggestions of using the strategy pattern (and the factory pattern as I see it would just be a helper to achieve the polymorphism above). So please, if anyone has concrete suggestions as to how to design these classes the best way I would be really grateful! Please also consider whether I have chosen the objects correctly too, or if they need to be redesigned. (Responses like "you should consider the factory pattern" will obviously not be helpful... I've already been down that road and I'm stumped at precisely how in this case) Regards, Anders The code (very simplified, don’t mind the fact that I’m using strings instead of enums, not using a config file for data etc, that will be done as necessary in the real application once I get the hang of these design problems): public abstract class Service { protected Dictionary<string, int> _hours; protected const int SMALL = 2; protected const int MEDIUM = 8; public int NumberOfProducts { get; set; } public abstract int GetHours(); } public class Writing : Service { public Writing(int numberOfProducts) { NumberOfProducts = numberOfProducts; _hours = new Dictionary<string, int> { { "small", 125 }, { "medium", 100 }, { "large", 60 } }; } public override int GetHours() { if (NumberOfProducts <= SMALL) return _hours["small"] * NumberOfProducts; if (NumberOfProducts <= MEDIUM) return (_hours["small"] * SMALL) + (_hours["medium"] * (NumberOfProducts - SMALL)); return (_hours["small"] * SMALL) + (_hours["medium"] * (MEDIUM - SMALL)) + (_hours["large"] * (NumberOfProducts - MEDIUM)); } } public class Analysis : Service { public Analysis(int numberOfProducts) { NumberOfProducts = numberOfProducts; _hours = new Dictionary<string, int> { { "small", 56 }, { "medium", 104 }, { "large", 200 } }; } public override int GetHours() { if (NumberOfProducts <= SMALL) return _hours["small"]; if (NumberOfProducts <= MEDIUM) return _hours["medium"]; return _hours["large"]; } } public partial class Form1 : Form { public Form1() { InitializeComponent(); List<int> quantities = new List<int>(); for (int i = 0; i < 100; i++) { quantities.Add(i); } comboBoxNumberOfProducts.DataSource = quantities; } private void comboBoxNumberOfProducts_SelectedIndexChanged(object sender, EventArgs e) { Service writing = new Writing((int) comboBoxNumberOfProducts.SelectedItem); Service analysis = new Analysis((int) comboBoxNumberOfProducts.SelectedItem); labelWriterHours.Text = writing.GetHours().ToString(); labelAnalysisHours.Text = analysis.GetHours().ToString(); } }

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  • When should you use intermediate variables for expressions?

    - by froadie
    There are times that one writes code such as this: callSomeMethod(someClass.someClassMethod()); And other times when one would write the same code like this: int result = someClass.someClassMethod(); callSomeMethod(result); This is just a basic example to illustrate the point. My question isn't if you should use an intermediate variable or not, as that depends on the code and can sometimes be a good design decision and sometimes a terrible one. The question is - when would you choose one method over the other? What factors would you consider when deciding whether to use an intermediate step? (I'd assume length and understandability of the fully inlined code would have something to do with it...)

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