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  • how to handle exceptions/errors in php?

    - by fayer
    when using 3rd part libraries they tend to throw exceptions to the browser and hence kill the script. eg. if im using doctrine and insert a duplicate record to the database it will throw an exception. i wonder, what is best practice for handling these exceptions. should i always do a try...catch? but doesn't that mean that i will have try...catch all over the script and for every single function/class i use? Or is it just for debugging? i don't quite get the picture. Cause if a record already exists in a database, i want to tell the user "Record already exists". And if i code a library or a function, should i always use "throw new Expcetion($message, $code)" when i want to create an error? Please shed a light on how one should create/handle exceptions/errors. Thanks

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  • Measuring time spent in application / thread

    - by Adamski
    I am writing a simulation in Java whereby objects act under Newtonian physics. An object may have a force applied to it and the resulting velocity causes it to move across the screen. The nature of the simulation means that objects move in discrete steps depending on the time ellapsed between the current and previous iteration of the animation loop; e.g public void animationLoop() { long prev = System.currentTimeMillis(); long now; while(true) { long now = System.currentTimeMillis(); long deltaMillis = now - prev; prev = now; if (deltaMillis > 0) { // Some time has passed for (Mass m : masses) { m.updatePosition(deltaMillis); } // Do all repaints. } } } A problem arises if the animation thread is delayed in some way causing a large amount of time to ellapse (the classic case being under Windows whereby clicking and holding on minimise / maximise prevents a repaint), which causes objects to move at an alarming rate. My question: Is there a way to determine the time spent in the animation thread rather than the wallclock time, or can anyone suggest a workaround to avoid this problem? My only thought so far is to contstrain deltaMillis by some upper bound.

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  • Saving an IP adddress to DB

    - by Mark
    I want to save a user's IP address to my database just in case any legal issues come up and we need to track down who performed what action. Since I highly doubt I will ever actually need to use this data (well, maybe for counting unique hits or something) do you think I can just dump the REMOTE_ADDR into a field? If so, what should the length of that field be? 39 chars should fit an IPv6 address, no? I don't know if I'll ever get any of those, but just in case...

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  • Error: Too Many Arguments Specified when Inserting Values from ASP.NET to SQL Server

    - by SidC
    Good Afternoon All, I have a wizard control that contains 20 textboxes for part numbers and another 20 for quantities. I want the part numbers and quantities loaded into the following table: USE [Diel_inventory] GO /****** Object: Table [dbo].[QUOTEDETAILPARTS] Script Date: 05/09/2010 16:26:54 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[QUOTEDETAILPARTS]( [QuoteDetailPartID] [int] IDENTITY(1,1) NOT NULL, [QuoteDetailID] [int] NOT NULL, [PartNumber] [float] NULL, [Quantity] [int] NULL, CONSTRAINT [pkQuoteDetailPartID] PRIMARY KEY CLUSTERED ( [QuoteDetailPartID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO ALTER TABLE [dbo].[QUOTEDETAILPARTS] WITH CHECK ADD CONSTRAINT [fkQuoteDetailID] FOREIGN KEY([QuoteDetailID]) REFERENCES [dbo].[QUOTEDETAIL] ([ID]) ON UPDATE CASCADE ON DELETE CASCADE GO Here's the snippet from my sproc for this insert: set @ID=scope_identity() Insert into dbo.QuoteDetailParts (QuoteDetailPartID, QuoteDetailID, PartNumber, Quantity) values (@ID, @QuoteDetailPartID, @PartNumber, @Quantity) When I run the ASPX page, I receive an error that there are too many arguments specified for my stored procedure. I understand why I'm getting the error, given the above table layout. However, I need help in structuring my insert syntax to look for values in all 20 PartNumber and Quantity field pairs. Thanks, Sid

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  • How would you code an efficient Circular Buffer in Java or C#

    - by Cheeso
    I want a simple class that implements a fixed-size circular buffer. It should be efficient, easy on the eyes, generically typed. EDIT: It need not be MT-capable, for now. I can always add a lock later, it won't be high-concurrency in any case. Methods should be: .Add and I guess .List, where I retrieve all the entries. On second thought, Retrieval I think should be done via an indexer. At any moment I will want to be able to retrieve any element in the buffer by index. But keep in mind that from one moment to the next Element[n] may be different, as the Circular buffer fills up and rolls over. This isn't a stack, it's a circular buffer. Regarding "overflow": I would expect internally there would be an array holding the items, and over time the head and tail of the buffer will rotate around that fixed array. But that should be invisible from the user. There should be no externally-detectable "overflow" event or behavior. This is not a school assignment - it is most commonly going to be used for a MRU cache or a fixed-size transaction or event log.

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  • What technologies/tools do people use to implement live websites ?

    - by MadSeb
    Hi, I have the following situation: -I have a server A hooked up to a piece of hardware that sends values and information out of every second. Programs on the server machine can read these values. This server A is in a very remote location so Internet connection is very slow and not reliable but the connection does exist. Let's say it's a weather station in the Arctic. -Users from the home location want to monitorize the weather values somehow. Well, the users can use a remote desktop connection the server A but that would be too too slow. My idea is somehow to have a website on a web server (let's call the webserver - B and B is in a home location ) and make the server A connect to the server B and somehow send values and the web application reads the values and displays them....... but how to do such a system ?? I know I can use MySQL and have the server A connect to a SQL server on server B and send INSERT queries and have the web application running on server B constantly read from the SQL server but I think that would be way way too slow and I think there has to be a better solution. Any ideas ? BTW. The users should be able to send information to the weather station from the website as well ( so an ADMIN user should be allowed to shut down the weather station from the website or whatever) Best regards, MadSeb

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  • C++ game designing & polymorphism question

    - by Kotti
    Hi! I'm trying to implement some sort of 'just-for-me' game engine and the problem's plot goes the following way: Suppose I have some abstract interface for a renderable entity, e.g. IRenderable. And it's declared the following way: interface IRenderable { // (...) // Suppose that Backend is some abstract backend used // for rendering, and it's implementation is not important virtual void Render(Backend& backend) = 0; }; What I'm doing right now is something like declaring different classes like class Ball : public IRenderable { virtual void Render(Backend& backend) { // Rendering implementation, that is specific for // the Ball object // (...) } }; And then everything looks fine. I can easily do something like std::vector<IRenderable*> items, push some items like new Ball() in this vector and then make a call similiar to foreach (IRenderable* in items) { item->Render(backend); } Ok, I guess it is the 'polymorphic' way, but what if I want to have different types of objects in my game and an ability to manipulate their state, where every object can be manipulated via it's own interface? I could do something like struct GameState { Ball ball; Bonus bonus; // (...) }; and then easily change objects state via their own methods, like ball.Move(...) or bonus.Activate(...), where Move(...) is specific for only Ball and Activate(...) - for only Bonus instances. But in this case I lose the opportunity to write foreach IRenderable* simply because I store these balls and bonuses as instances of their derived, not base classes. And in this case the rendering procedure turns into a mess like ball.Render(backend); bonus.Render(backend); // (...) and it is bad because we actually lose our polymorphism this way (no actual need for making Render function virtual, etc. The other approach means invoking downcasting via dynamic_cast or something with typeid to determine the type of object you want to manipulate and this looks even worse to me and this also breaks this 'polymorphic' idea. So, my question is - is there some kind of (probably) alternative approach to what I want to do or can my current pattern be somehow modified so that I would actually store IRenderable* for my game objects (so that I can invoke virtual Render method on each of them) while preserving the ability to easily change the state of these objects? Maybe I'm doing something absolutely wrong from the beginning, if so, please point it out :) Thanks in advance!

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  • Is incrementing in a loop exponential time?

    - by user356106
    I've a simple but confusing doubt about whether the program below runs in exponential time. The question is : given a +ve integer as input, print it out. The catch is that you deliberately do this in a loop, like this: int input,output=0; cininput; while(input--) ++output; // Takes time proportional to the value of input cout<< output; I'm claiming that this problem runs in exponential time. Because, the moment you increase the # of bits in input by 1, the program takes double the amount of time to execute. Put another way, to print out log2(input) bits, it takes O(input) time. Is this reasoning right?

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  • What information do you capture when your software crashes in the field?

    - by Russ
    I am working on rewriting my unexpected error handling process, and I would like to ask the community: What information do you capture both automatic, and manually, when software you have written crashes? Right now, I capture a few items, some of which are: Automatic: Name of app that crashed Version of app that crashed Stack trace Operating System version RAM used by the application Number of processors Screen shot: (Only on non-public applications) User name and contact information (from Active Directory) Manual: What context is the user in (i.e.: what company, tech support call number, RA number, etc...) When did the user expect to happen? (Typical response: "Not to crash”) Steps to reproduce. What other bits of information do you capture that helps you discover the true cause of an applications problem, especially given that most users simply mash the keyboard when asked to tell you what happened. For the record I’m using C#, WPF and .NET version 4, but I don’t necessarily want to limit myself to those. Related: http://stackoverflow.com/questions/1226671/what-to-collect-information-when-software-crashes Related: http://stackoverflow.com/questions/701596/what-should-be-included-in-the-state-of-the-art-error-and-exception-handling-stra

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  • Need some clarification on the ANSI/SPARC 3-tier database architecture.

    - by Moonshield
    Hi there, I'm currently revising for a databases exam and looking over some past papers, but there's one question that I'm slightly unsure about and was wondering if someone could offer some assistance. "Describe EACH of the THREE levels of the ANSI SPARC 3 level architecture. Your answer should include the purpose of EACH of the schemas, the level of abstraction they provide and the software tools that would be used to access and support them." As I understand it (although please correct me if I'm wrong): the internal schema specifies the physical storage of the data; the conceptual schema specifies the structure of the database and the domains; and the external schemas are how the database is viewed by "users" (applications, etc.). As for the abstraction, I understand that the conceptual layer means that the physical data storage can be altered without the end user being affected, likewise the The bit that I'm not sure about is what tools are used to access and support each layer. Would the internal schema be handled by the DBMS, the conceptual schema handled by some sort of DDL interpreter and the external schema handled by a DML interpreter (or have I misunderstood what each level does)? Any assistance would be greatly appreciated. Thanks, Moonshield

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  • Best approch to dynamically filter .net objects

    - by maxba
    The project i´m working currently on has a way to define a filter to filter objects from a database. This filter is a pretty straitforward class containing filtercriteria that will be combined to a sql where-clause. The goal now is to use this filter class to filter .net objects as well. So the filter for example defines, that the title property of the object that it is applied to must contain some userdefined string etc. What are ways to approch this problem? What should the filter return instead of the sql where-clause and how can it be applied to the object? I´m thinking about this for hours and don´t yet have even a slight idea how to solve this. Been thinking about reflection, dynamic code execution, building expressions but still haven´t found an acutal starting point.

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  • Brilliant features of C++

    - by John
    (Following Features to remove from C++ and Desired features for C++, I thought why not complete the trio...) What C++ features would you not change? What features are elegantly and brilliantly implemented and still look better than other popular languages?

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  • designing an ASP.NET MVC partial view - showing user choices within a large set of choices

    - by p.campbell
    Consider a partial view whose job is to render markup for a pizza order. The desire is to reuse this partial view in the Create, Details, and Update views. It will always be passed an IEnumerable<Topping>, and output a multitude of checkboxes. There are lots... maybe 40 in all (yes, that might smell). A-OK so far. Problem The question is around how to include the user's choices on the Details and Update views. From the datastore, we've got a List<ChosenTopping>. The goal is to have each checkbox set to true for each chosen topping. What's the easiest to read, or most maintainable way to achieve this? Potential Solutions Create a ViewModel with the List and List. Write out the checkboxes as per normal. While writing each, check whether the ToppingID exists in the list of ChosenTopping. Create a new ViewModel that's a hybrid of both. Perhaps call it DisplayTopping or similar. It would have property ID, Name and IsUserChosen. The respective controller methods for Create, Update, and Details would have to create this new collection with respect to the user's choices as they see fit. The Create controller method would basically set all to false so that it appears to be a blank slate. The real application isn't pizza, and the organization is a bit different from the fakeshot, but the concept is the same. Is it wise to reuse the control for the 3 different scenarios? How better can you display the list of options + the user's current choices? Would you use jQuery instead to show the user selections? Any other thoughts on the potential smell of splashing up a whole bunch of checkboxes?

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  • What's a good icon to represent a legend or a key for a diagram?

    - by Bears will eat you
    I'm implementing a small web app widget that shows a legend/key for a diagram (or chart/map/graph/whatever), but only during mouseover of the widget. It's basically just going to be a div with a background image. What would be a good icon that communicates "I show the legend" or "I am the legend" to the unfamiliar users? I'm looking for something in the 10x10 to 20x20 pixel range. Assuming that a legend is the same thing as a key (is it?) then I could use a small icon of a key (like you'd unlock a door with) but that seems cheesy or unclear at worst. I'm not sure that's really the clearest way to do it. Is there an icon that should instantly remind users of a legend?

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  • Getting the final value to this MySQL query...

    - by Jack W-H
    I've got my database set up with three tables - code, tags, and code_tags for tagging posts. This will be the SQL query processed when a post is submitted. Each tag is sliced up by PHP and individually inserted using these queries. INSERT IGNORE INTO tags (tag) VALUES ('$tags[1]'); SELECT tags.id FROM tags WHERE tag = '$tags[1]' ORDER BY id DESC LIMIT 1; INSERT INTO code_tags (code_id, tag_id) VALUES ($codeid, WHAT_GOES_HERE?) The WHAT_GOES_HERE? value at the end is what I need to know. It needs to be the ID of the tag that the second query fetched. How can I put that ID into the third query? I hope I explained that correctly. I'll rephrase if necessary.

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  • Managing libraries and imports in a programming language

    - by sub
    I've created an interpreter for a stupid programming language in C++ and the whole core structure is finished (Tokenizer, Parser, Interpreter including Symbol tables, core functions, etc.). Now I have a problem with creating and managing the function libraries for this interpreter (I'll explain what I mean with that later) So currently my core function handler is horrible: // Simplified version myLangResult SystemFunction( name, argc, argv ) { if ( name == "print" ) { if( argc < 1 ) { Error('blah'); } cout << argv[ 0 ]; } else if ( name == "input" ) { if( argc < 1 ) { Error('blah'); } string res; getline( cin, res ); SetVariable( argv[ 0 ], res ); } else if ( name == "exit ) { exit( 0 ); } And now think of each else if being 10 times more complicated and there being 25 more system functions. Unmaintainable, feels horrible, is horrible. So I thought: How to create some sort of libraries that contain all the functions and if they are imported initialize themselves and add their functions to the symbol table of the running interpreter. However this is the point where I don't really know how to go on. What I wanted to achieve is that there is e.g.: an (extern?) string library for my language, e.g.: string, and it is imported from within a program in that language, example: import string myString = "abcde" print string.at( myString, 2 ) # output: c My problems: How to separate the function libs from the core interpreter and load them? How to get all their functions into a list and add it to the symbol table when needed? What I was thinking to do: At the start of the interpreter, as all libraries are compiled with it, every single function calls something like RegisterFunction( string namespace, myLangResult (*functionPtr) ); which adds itself to a list. When import X is then called from within the language, the list built with RegisterFunction is then added to the symbol table. Disadvantages that spring to mind: All libraries are directly in the interpreter core, size grows and it will definitely slow it down.

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  • Can I change class types in a setter with an object-oriented language?

    - by user214626
    Hello, Here is the problem statement : Calling a setter on the object should result in the object to change to an object of a different class, which language can support this ? Ex. I have a class called "Man" (Parent Class), and two children namely "Toddler" and "Old Man", they are its children because they override a behaviour in Man called as walk.( i.e Toddler sometimes walks using both his hands and legs kneeled down and the Old man uses a stick to support himself). The Man class has a attribute called age, I have a setter on Man,say it is called setAge(int ageValue). I have 3 objects, 2 toddlers, 1 old-Man. (The system is up and running,i guess when we say objects it is obvious) .I will make this call, toddler.setAge(80), I expect the toddler to change to an object of type Old Man. Is this possible.Please suggest. Thanks,

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  • What are the differences between enterprise software/architecture patterns and open source software?

    - by Jeffrey
    I am mainly a business app developer and I hear terms like CQRS, ServiceBus, SOA, DDD, BDD, AOP a lot. My question is that do these patterns/practices exist only in the "enterprise" world? In contract to the enterprise world is the open source community. Highly trafficked sites like Digg, LiveJournal whenever there is an article mentioning about how they built/scaled their sites all I am hearing is what open source software (Memcached, NoSQL) they used in order to scale/simplify the way they tackle software problems and they rarely mention those above terms. Is it because they are not as sophisticated as those of enterprise level software (I doubt it)? Or are people just making up those terms/practices/patterns in order to keep them jobs? Or am I confusing myself with differences between software development and internet website scaling?

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  • C# Linq: Can you merge DataContexts?

    - by Andreas Grech
    Say I have one database, and this database has a set of tables that are general to all Clients and some tables that are specific to certain clients. Now what I have in mind is creating a primary DataContext that includes only the tables that are general to all the clients, and then create separate DataContexts that contain only the tables that are specific to the client. Is there a way to kind of "merge" DataContexts so that it becomes one context? So for Client A, I need one DataContext that includes both the general tables and also the tables for that specific client (retrieved from two different DataContexts) ? [Update] What I think I can do is, from the Partial Class of the DataContext instead of letting my DataContext inherit from DataContext I make it inherit from MyDataContext; that way, the tables from MyDataContext and the other DataContext will be available in one DataContext class. What do you think about this approach? Of course with something like this you can only merge two datacontexts at once though...

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  • What do you find wrong or strange in this Perl code to simulate objects without bless?

    - by user350571
    I'm new to Perl and its blessing stuff to imitate class like functionality made me feel strange I even had to go to the bathroom. Now, please tell me: what do you don't like, find wrong or strange with this code: sub Person { my $age = shift || 15; return { printAge => sub { print "Age -> $age\n"; }, changeAge => sub { $age = shift } } } my $p = Person(); my $p2 = Person(27); $p->{printAge}->(); $p->{changeAge}->(30); $p->{printAge}->(); $p2->{printAge}->();

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  • Problem with IE 6 page loading.

    - by Puneet Dudeja
    I have a website which works fine in all browsers except in IE6. The pages content is inside a div loaded with a background image. The page layout gets very nasty and image does not load when the page is opened for first time, but when the same page is opened for the second time and any subsequent times, then it loads perfectly. This scenario is with every page in the site. Please help.

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  • wpf command pattern

    - by evan
    I have a wpf gui which displays a list of information in separate window and in a separate thread from the main application. As the user performs actions in the main window the side window is updated. (For example if you clicked page down in the main window a listbox in the side window would page down). Right now the architecture for this application feels very messy and I'm sure there is a cleaner way to do it. It looks like this: Main Window contains a singleton SideWindowControl which communicates with an instance of the SideWindowDisplay using events - so, for example, the pagedown button would work like: 1) the event handler of the button on the main window calls SideWindowControl.PageDown() 2) in the PageDown() function a event is created and thrown. 3) finally the gui, ShowSideWindowDisplay is subscribing to the SideWindowControl.Actions event handles the event and actually scrolls the listbox down - note because it is in a different thread it has to do that by running the command via Dispatcher.Invoke() This just seems like a very messy way to this and there must be a clearer way (The only part that can't change is that the main window and the side window must be on different threads). Perhaps using WPF commands? I'd really appreciate any suggestions!! Thanks

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