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  • Exception design: Custom exceptions reading data from file?

    - by User
    I have a method that reads data from a comma separated text file and constructs a list of entity objects, let's say customers. So it reads for example, Name Age Weight Then I take these data objects and pass them to a business layer that saves them to a database. Now the data in this file might be invalid, so I'm trying to figure out the best error handling design. For example, the text file might have character data in the Age field. Now my question is, should I throw an exception such as InvalidAgeException from the method reading the file data? And suppose there is length restriction on the Name field, so if the length is greater than max characters do I throw a NameTooLongException or just an InvalidNameException, or do I just accept it and wait until the business layer gets a hold of it and throw exceptions from there? (If you can point me to a good resource that would be good too)

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  • Ideal way to cancel an executing AsyncTask

    - by Samuh
    I am running remote audio-file-fetching and audio file playback operations in a background thread using AsyncTask. A Cancellable progress bar is shown for the time the fetch operation runs. I want to cancel/abort the AsyncTask run when the user cancels (decides against) the operation. What is the ideal way to handle such a case?

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  • Is there a Standard or Best Practice for Perl Progams, as opposed to Perl Modules?

    - by swestrup
    I've written any number of perl modules in the past, and more than a few stand-alone perl programs, but I've never released a multi-file perl program into the wild before. I have a perl program that is almost at the beta stage and is going to be released open source. It requires a number of data files, as well as some external perl modules -- some I've written myself, and some from CPAN -- that I'll have to bundle with it so as to ensure that someone can just download my program and install it without worrying about hunting for obscure modules. So, it sounds to me like I need to write an installer to copy all the files to standard locations so that a user can easily install everything. The trouble is, I have no idea what the standard practice would be for this. I have found lots of tutorials on perl module standards, but none on perl program standards. Does anyone have any pointers to standard paths, installation proceedures, etc, for perl programs? This is going to be complicated by the fact that the program is multi-platform. I've been testing it in Linux, but its designed to work equally well in Windows.

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  • What is your strategy to avoid dynamic typing errors in Python (NoneType has not attribute x)?

    - by Koen Bok
    Python is one of my favorite languages, but I really have a love/hate relationship with it's dynamicness. Apart from the advantages, it often results in me forgetting to check a type, trying to call an attribute and getting the NoneType (or any other) has no attribute x error. A lot of them are pretty harmless but if not handled correctly they can bring down your entire app/process/etc. Over time I got better predicting where these could pop up and adding explicit type checking, but because I'm only human I miss one occasionally and then some end-user finds it. So I'm interested in your strategy to avoid these. Do you use type-checking decorators? Maybe special object wrappers? Please share...

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  • Java Date vs Calendar

    - by Marty Pitt
    Could someone please advise the current "best practice" around Date and Calendar types. When writing new code, is it best to always favour Calendar over Date, or are there circumstances where Date is the more appropriate datatype?

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  • Singleton class design in C#, are these two classes equivalent?

    - by Oskar
    I was reading up on singleton class design in C# on this great resource and decided to go with alternative 4: public sealed class Singleton1 { static readonly Singleton1 _instance = new Singleton1(); static Singleton1() { } Singleton1() { } public static Singleton1 Instance { get { return _instance; } } } Now I wonder if this can be rewritten using auto properties like this? public sealed class Singleton2 { static Singleton2() { Instance = new Singleton2(); } Singleton2() { } public static Singleton2 Instance { get; private set; } } If its only a matter of readability I definitely prefer the second version, but I want to get it right.

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  • VB Classes Best Practice - give all properties values?

    - by Becky Franklin
    Sorry if this is a bit random, but is it good practice to give all fields of a class a value when the class is instanciated? I'm just wondering if its better practice to have a constuctor that takes no parameters and gives all the fields default values, or whether fields that have values should be assigned and others left alone until required? I hope that makes sense, Becky

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  • Security implications of writing files using PHP

    - by susmits
    I'm currently trying to create a CMS using PHP, purely in the interest of education. I want the administrators to be able to create content, which will be parsed and saved on the server storage in pure HTML form to avoid the overhead that executing PHP script would incur. Unfortunately, I could only think of a few ways of doing so: Setting write permission on every directory where the CMS should want to write a file. This sounds like quite a bad idea. Setting write permissions on a single cached directory. A PHP script could then include or fopen/fread/echo the content from a file in the cached directory at request-time. This could perhaps be carried out in a Mediawiki-esque fashion: something like index.php?page=xyz could read and echo content from cached/xyz.html at runtime. However, I'll need to ensure the sanity of $_GET['page'] to prevent nasty variations like index.php?page=http://www.bad-site.org/malicious-script.js. I'm personally not too thrilled by the second idea, but the first one sounds very insecure. Could someone please suggest a good way of getting this done?

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  • Design suggestions for creating document management structure using hidden shares.

    - by focus.nz
    I need to add some document management functionality into my software. Documents will be grouped by company name and project name. The folders need to be accessed by the application using the id numbers of clients/projects, but also easily browsed by the end user using windows explorer. Clients and Projects will be stored in a database. I am thinking of having the software create the folders using the friendly name and then using a hidden share with the id number for the software to access the files. The folder structure would be something like this --Company 1 (Company-1234$) -- Project 101 (Project-101$) -- Project 102 (Project-102$) -- Project 103 (Project-103$) -- Company 2 (Company-5678$) -- Project 201 (Project-201$) -- Project 202 (Project-202$) -- Project 203 (Project-203$) So in the example above there would be a company called "Company 1" with a ID of "1234". When browsing the folders using windows explorer the user would see \\ServerName\Documents\Company1 and you could also access the same folder from \\ServerName\Documents\Company-1234$ By using the hidden share, if the company name changes or its renamed for some reason it doesn't break the link in the application because its using the hidden shared based on the ID that never changes. Will having hundreds (maybe thousands) or hidden shares on a server provide a huge performance hit? Does any one have any suggestions or alternatives to provide this feature?

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  • Separation of concerns and authentication

    - by Tom Gilder
    I'm trying to be a Good Developer and separate my concerns out. I've got an ASP.NET MVC project with all my web code, and a DAL project with all the model code. Sometimes code in the DAL needs to check if the current user is authorized to perform some actions, by checking something like CurrentUser.IsAdmin. For the web site, the current is derived from the Windows username (from HttpContext.Current.User.Identity), but this is clearly a web concern and shouldn't be coupled to the DAL. What's the best pattern to loosely couple the authentication? Should the DAL be asking the MVC code for a username, or the MVC be telling the DAL? Are there advantages or disadvantages to one or the other? Thank you!

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  • SVN best practice - checking out root folder

    - by Stephen Dolier
    Hi all, quick question about svn checkout best practice. Once the structure of a repository is set up, ie trunk, branches, tags, is it normal to have the root checked out to our local machines. Or should you only check out the trunk if that's what you are working on or a branch if we so choose to create one. The reason i ask is that every time someone creates a branch or tag we all get a copy when we do an update. btw, we're recently migrated from vss.

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  • To be effective on your home projects is it better using the same technologies used at work?

    - by systempuntoout
    To be more productive and effective, is it better to start developing an home project using the same technologies used at work? I'm not talking about a simple hello world web page but an home project with all bells and whistles that one day, maybe, you could sell on internet. This dilemma is often subject of flames between me and a friend. He thinks that if you want to make a great home-made project you need to use the same technologies used daily at work staying in the same scope too; for example, a c++ computer game programmer should develope an home-made c++ game. I'm pretty sure that developing using the same technologies used at work can be more productive at beginning, but surely less exciting and stimulating of working with other languages\ides\libraries out of your daily job. What's your opinion about that?

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  • Looking for a better design: A readonly in-memory cache mechanism

    - by Dylan Lin
    Hi all, I have a Category entity (class), which has zero or one parent Category and many child Categories -- it's a tree structure. The Category data is stored in a RDBMS, so for better performance, I want to load all categories and cache them in memory while launching the applicaiton. Our system can have plugins, and we allow the plugin authors to access the Category Tree, but they should not modify the cached items and the tree(I think a non-readonly design might cause some subtle bugs in this senario), only the system knows when and how to refresh the tree. Here are some demo codes: public interface ITreeNode<T> where T : ITreeNode<T> { // No setter T Parent { get; } IEnumerable<T> ChildNodes { get; } } // This class is generated by O/R Mapping tool (e.g. Entity Framework) public class Category : EntityObject { public string Name { get; set; } } // Because Category is not stateless, so I create a cleaner view class for Category. // And this class is the Node Type of the Category Tree public class CategoryView : ITreeNode<CategoryView> { public string Name { get; private set; } #region ITreeNode Memebers public CategoryView Parent { get; private set; } private List<CategoryView> _childNodes; public IEnumerable<CategoryView> ChildNodes { return _childNodes; } #endregion public static CategoryView CreateFrom(Category category) { // here I can set the CategoryView.Name property } } So far so good. However, I want to make ITreeNode interface reuseable, and for some other types, the tree should not be readonly. We are not able to do this with the above readonly ITreeNode, so I want the ITreeNode to be like this: public interface ITreeNode<T> { // has setter T Parent { get; set; } // use ICollection<T> instead of IEnumerable<T> ICollection<T> ChildNodes { get; } } But if we make the ITreeNode writable, then we cannot make the Category Tree readonly, it's not good. So I think if we can do like this: public interface ITreeNode<T> { T Parent { get; } IEnumerable<T> ChildNodes { get; } } public interface IWritableTreeNode<T> : ITreeNode<T> { new T Parent { get; set; } new ICollection<T> ChildNodes { get; } } Is this good or bad? Are there some better designs? Thanks a lot! :)

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  • Which Code Should Go Where in MVC Structure

    - by Oguz
    My problem is in somewhere between model and controller.Everything works perfect for me when I use MVC just for crud (create, read, update, delete).I have separate models for each database table .I access these models from controller , to crud them . For example , in contacts application,I have actions (create, read, update, delete) in controller(contact) to use model's (contact) methods (create, read, update, delete). The problem starts when I try to do something more complicated. There are some complex processes which I do not know where should I put them. For example , in registering user process. I can not just finish this process in user model because , I have to use other models too (sending mails , creating other records for user via other models) and do lots of complex validations via other models. For example , in some complex searching processes , I have to access lots of models (articles, videos, images etc.) Or, sometimes , I have to use apis to decide what I will do next or which database model I will use to record data So where is the place to do this complicated processes. I do not want to do them in controllers , Because sometimes I should use these processes in other controllers too. And I do not want to put these process in models because , I use models as database access layers .May be I am wrong,I want to know . Thank you for your answer .

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  • Best Design pattern for social media file transfer

    - by Onema
    Our system would like our clients to link their accounts with different social media sites like youtube, vimeo, facebook, myspace and so on. One of the benefits we would like to give to the user is to transfer, update and delete files they have uploaded to our sites and transfer them to the social media sites mentioned above. this files could be videos, images or audio. We started thinking about using a strategy pattern, as all of these sites share a common process ( authentication, connection, use the API to transfer/edit/delete the file ), but we soon realized that it may not work as me may want to use some of the extended functionality that is specific to each service (eg: associate a youtube video with a channel, or upload images to a specific album on facebook, and much, much more...) My question is, what would be the best Structural Design Patter to use for this scenario?

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  • Is jQuery always the answer?

    - by Kibbee
    I've come across a couple questions, such as this one, and I really have to wonder why "Use jQuery" seems to be the answer when somebody asks how to do something in JavaScript. I understand that jQuery can save you a lot of time, and can help you out a lot, especially when you are doing a lot of fancy JavaScript in your site. However, in instances like this, and in many other instances, it seems like it's just jumping around the problem instead of answering the question. I also feel like this builds too much dependency into libraries. I've seen way too many developers that simply rely too much on libraries, and if they encounter a situation where they didn't have the library, they would be completely unable to function. I feel like there are already enough developers who don't know JavaScript, without just telling everybody to not learn JavaScript, and use jQuery. So, just to reiterate the question. Do you think there's too much of a tendency to use jQuery, for small pieces of JavaScript, when most of the functionality of jQuery isn't being used. Should developers be fluent in the use of bare JavaScript so they don't get too dependent on using libraries? [Additional related conversation topic] Does the existence of jQuery give too much slack to web browser developers who write the JavaScript engines? If we just have workarounds to cover all the inconsistencies in JavaScript, what pressure is there on browser makers to ensure that their JavaScript library works as it should. I feel like this extrapolates the same problem discussed in SO Podcast #36 of "be conservative in what you send, liberal in what you accept". By being so liberal with bad JavaScript engines, and using a common library to work around the flaws, we are promoting their use, and extending the problem.

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  • Maintain List of Active Users for Web

    - by Bryan Marble
    Problem Statement - Would like to know if particular web app user is active (i.e. logged in and using site) and be able to query for list of active users or determine a user's activity status. Constraints - Doesn't need to be exact (i.e. if a user was active within a certain timeframe, that's ok to say that they're active even if they've closed their browser). I feel like there should be a design pattern for this type of problem but haven't been able to find anything here or elsewhere on the web. Approaches I'm considering: Maintain a table that is updated any time a user performs an action (or some subset of actions). Would then query for users that have performed an action within some threshold of time. Try to monitor session information and maintain a table that lists logged in users and times out after a certain period of time. Some other more standard way of doing this? How would you approach this problem (again, from a design pattern perspective)? Thanks!

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  • Only perform jquery effects/operations on certain pages

    - by Galen
    Up until now i've been dropping all my jquery code right inside the document.ready function. I'm thinking that for certain situations this isnt the best way to go. for example: If i want an animation to perform when a certain page loads what is the best way to go about that. $(document).ready(function() { $("#element_1").fadeIn(); $("#element_2").delay('100').fadeIn(); $("#element_3").delay('200').fadeIn(); }); If this is right inside of document.ready then every time ANY page loads it's going to check each line and look for that element. What is the best way to tell jquery to only perform a chunk of code on a certain page to avoid this issue.

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  • C# - Removing event handlers - FormClosing event or Dispose() method

    - by Andy
    Suppose I have a form opened via the .ShowDialog() method. At some point I attach some event handlers to some controls on the form. e.g. // Attach radio button event handlers. this.rbLevel1.Click += new EventHandler(this.RadioButton_CheckedChanged); this.rbLevel2.Click += new EventHandler(this.RadioButton_CheckedChanged); this.rbLevel3.Click += new EventHandler(this.RadioButton_CheckedChanged); When the form closes, I need to remove these handlers, right? At present, I am doing this when the FormClosing event is fired. e.g. private void Foo_FormClosing(object sender, FormClosingEventArgs e) { // Detach radio button event handlers. this.rbLevel1.Click -= new EventHandler(this.RadioButton_CheckedChanged); this.rbLevel2.Click -= new EventHandler(this.RadioButton_CheckedChanged); this.rbLevel3.Click -= new EventHandler(this.RadioButton_CheckedChanged); } However, I have seen some examples where handlers are removed in the Dispose() method. Is there a 'best-practice' way of doing this? (Using C#, Winforms, .NET 2.0) Thanks.

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  • Best approach for coding ?

    - by ahmed
    What should or how should I decide the best approach for coding as a smart programmer. I have just started programming last year in VB, and I keep on listening this statement. But I never could find by myself to choose the best approach for coding. When I search for a coding example on internet I find different types of approach to achieve the same target. So help me finding the best approach. (asp.net,vb.net)

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  • What are the Worst Software Project Failures Ever?

    - by Warren P
    Is there a good list of "worst software project failures ever" in the history of software development? For example in Canada a "gun registry" project spent around two billion dollars. (http://en.wikipedia.org/wiki/Gun_registry). This is of course, insane, even if the final product "sort of worked". I have heard of an FBI Case file system which there have been several attempts to rewrite, all of them so far, failures. There is a book on the subject (Software Runaways). There doesn't seem to be be a software "boondoggle" list or "fiasco" list on Wikipedia that I can see. (Update: Therac-25 would be the 'winner' of this question, except that I was internally thinking more of Software projects that had as their deliverable, mainly software, as opposed to firmware projects like Therac-25, where the hardware and firmware together are capable of killing people. In terms of pure software monetary debacles, which was my intended question, there are several contenders.)

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