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Articles indexed Monday May 17 2010

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  • PDOException “could not find driver”

    - by Mike
    I have just installed Debian Lenny with Apache, MySQL, and PHP and I am receiving a PDOException could not find driver. This is the specific line of code it is referring to: $dbh = new PDO('mysql:host=' . DB_HOST . ';dbname=' . DB_NAME, DB_USER, DB_PASS) DB_HOST, DB_NAME, DB_USER, and DB_PASS are constants that I have defined. It works fine on the production server (and on my previous Ubuntu Server setup). Is this something to do with my PHP installation? Searching the internet has not helped, all I get is experts-exchange and examples, but no solutions.

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  • propositional theorems

    - by gcc
    wang's theorem to prove theorems in propositonal calculus Label Sequent Comment S1: P ? Q, Q ? R, ¬R ? ¬P Initial sequent. S2: ¬P ? Q, ¬Q ? R, ¬R ? ¬P Two applications of R5. S3: ¬P ? Q, ¬Q ? R ? ¬P, R Rl. S4: ¬P, ¬Q ? R ? ¬P, R S4 and S5 are obtained from S3 with R3. Note that S4 is an axiom since P appears on both sides of the sequent ar- row at the top level. S5: Q, ¬Q ? R ? ¬P, R The other sequent generated by the ap- plication of R3. S6: Q, ¬Q ? ¬P, R S6 and S7 are obtained from S5 using R3. S7: Q, R ? ¬P, R This is an axiom. S8: Q ? ¬P, R, Q Obtained from S6 using R1. S8 is an axiom. The original sequent is now proved, since it has successfully been transformed into a set of three axioms with no unproved sequents left over. //R1,R2,R3,R4,R5 is transformation myhomework is so complicate as you can see and i must finish homework in 4 days i just want help ,can you show me how i should construct the algorithm or how i should take and store the input

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  • Free service that allows storing game data online?

    - by StackedCrooked
    I have created a small game in Java and I would like to add the ability for a player to publish his highscores online. I'm willing to write the server software myself (it's easy these days with Ruby Mongrel, or even C++). All I just need to have some sort hosting. One solution that immediately comes to mind is Amazon EC2. But that's kind of expensive for my needs. Since the requirements are very minimal (I don't even need a website, just a web service) I think there may be a cheaper solution out there. Does anyone know of a free or cheap provider for this kind of thing?

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  • Webfaction: How do I run a Static/Perl app and Django app under the same website

    - by swisstony
    I have an existing Perl app that I'm moving to a Webfaction website. I will be adding Django apps to this Webfaction website too. I would like the Django app to get first call and so would want its URL path to be / This would allow me to add any new URLs to the urls.py I wish as my app grows. If the URL doesn't match anything in the urls.py I would like it to get passed to the static Perl app. For example /app1 - Django /app2 - Django Everything else not picked up by urls.py I would want going to my Perl app For example: /index.html - Static/Perl app /about.html - Static/Perl app /contact.html - Static/Perl app /apps/perlapp1.cgi - Static/Perl app etc How do I go about achieving this in Webfaction?

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  • Dont Throw Duplicate Exceptions

    In your code, youll sometimes have write code that validates input using a variety of checks.  Assuming you havent embraced AOP and done everything with attributes, its likely that your defensive coding is going to look something like this: public void Foo(SomeClass someArgument) { if(someArgument == null) { throw new InvalidArgumentException("someArgument"); } if(!someArgument.IsValid()) { throw new InvalidArgumentException("someArgument"); }   // Do Real Work } Do you see a problem here?  Heres the deal Exceptions should be meaningful.  They have value at a number of levels: In the code, throwing an exception lets the develop know that there is an unsupported condition here In calling code, different types of exceptions may be handled differently At runtime, logging of exceptions provides a valuable diagnostic tool Its this last reason I want to focus on.  If you find yourself literally throwing the exact exception in more than one location within a given method, stop.  The stack trace for such an exception is likely going to be identical regardless of which path of execution led to the exception being thrown.  When that happens, you or whomever is debugging the problem will have to guess which exception was thrown.  Guessing is a great way to introduce additional problems and/or greatly increase the amount of time require to properly diagnose and correct any bugs related to this behavior. Dont Guess Be Specific When throwing an exception from multiple code paths within the code, be specific.  Virtually ever exception allows a custom message use it and ensure each case is unique.  If the exception might be handled differently by the caller, than consider implementing a new custom exception type.  Also, dont automatically think that you can improve the code by collapsing the if-then logic into a single call with short-circuiting (e.g. if(x == null || !x.IsValid()) ) that will guarantee that you cant easily throw different information into the message as easily as constructing the exception separately in each case. The code above might be refactored like so:   public void Foo(SomeClass someArgument) { if(someArgument == null) { throw new ArgumentNullException("someArgument"); } if(!someArgument.IsValid()) { throw new InvalidArgumentException("someArgument"); }   // Do Real Work } In this case its taking advantage of the fact that there is already an ArgumentNullException in the framework, but if you didnt have an IsValid() method and were doing validation on your own, it might look like this: public void Foo(SomeClass someArgument) { if(someArgument.Quantity < 0) { throw new InvalidArgumentException("someArgument", "Quantity cannot be less than 0. Quantity: " + someArgument.Quantity); } if(someArgument.Quantity > 100) { throw new InvalidArgumentException("someArgument", "SomeArgument.Quantity cannot exceed 100. Quantity: " + someArgument.Quantity); }   // Do Real Work }   Note that in this last example, Im throwing the same exception type in each case, but with different Message values.  Im also making sure to include the value that resulted in the exception, as this can be extremely useful for debugging.  (How many times have you wished NullReferenceException would tell you the name of the variable it was trying to reference?) Dont add work to those who will follow after you to maintain your application (especially since its likely to be you).  Be specific with your exception messages follow DRY when throwing exceptions within a given method by throwing unique exceptions for each interesting case of invalid state. Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Silverlight 4 Tools, WCF RIA Services and Themes Released

    This morning we published the final release of the Silverlight 4 Tools for Visual Studio and WCF RIA Services. In April, when Silverlight 4 was released, the tools were still in RC status. Today, they are no longer and are officially released. There is no new update to Silverlight itself, but these tools are the final bits of this version. Get the Tools If you have a clean machine you can get everything you need using the Web Platform Installer by clicking on the link at the Silverlight community...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Windows HPC Server 08 suitability for Matlabs

    - by blade
    I want to setup another Hyper-V VM for installing Matlabs/doing some compute-intensive programming using C. I keep thinking that Windows Server HPC 2008 is designed for this sort of work. Would I be on the right track to setup a single VM with this OS and install this software? Or is HPC more for grid/distributed computing? Thanks

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  • VSS Information: Where do I find it?

    - by MJ
    I'm currently taking care of backups for about 100 clients, and I'm really getting hammered with VSS issues. I've tried many different things, re-regsitering the VSS Dlls, reboots, patches, etc. What I want to know: Where can I find some detailed, technical information about VSS.

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  • Relay WCF Service

    - by Matt Ruwe
    This is more of an architectural and security question than anything else. I'm trying to determine if a suggested architecture is necessary. Let me explain my configuration. We have a standard DMZ established that essentially has two firewalls. One that's external facing and the other that connects to the internal LAN. The following describes where each application tier is currently running. Outside the firewall: Silverlight Application In the DMZ: WCF Service (Business Logic & Data Access Layer) Inside the LAN: Database I'm receiving input that the architecture is not correct. Specifically, it has been suggested that because "a web server is easily hacked" that we should place a relay server inside the DMZ that communicates with another WCF service inside the LAN which will then communicate with the database. The external firewall is currently configured to only allow port 443 (https) to the WCF service. The internal firewall is configured to allow SQL connections from the WCF service in the DMZ. Ignoring the obvious performance implications, I don't see the security benefit either. I'm going to reserve my judgement of this suggestion to avoid polluting the answers with my bias. Any input is appreciated. Thanks, Matt

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  • Short intruduction to OOP basics

    - by woo
    Hi. Can somebody point me to good intruductions into OOP main paradigms, like inheritance, polymorphism, incapsulation? I am looking for short article, about 2-3 pages, for very quick reading. Thank you very much.

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  • C# - Ensuring an assembly is called via a specified assembly

    - by Adam Driscoll
    Is there any built in functionality to determine if an assembly is being called from a particular assembly? I have assembly A which references assembly B. Assembly A exposes PowerShell cmdlets and outputs types that are found within B. Certain methods and properties with in types of exposed by B are of interest to types in assembly A but not of interest to consumers of PowerShell or anyone attempting to load types in B directly and call methods within it. I have looked into InternalsVisibleToAttribute but it would require extensive rework because of the use of interfaces. I was devising a shared key system that would later be obfuscated but that seemed clunky. Is there any way to ensure B is called only by A?

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  • MVC + Repository Pattern - Still depends on Data Model?

    - by Jack
    I've started a project for school in which I am using ASP.NET MVC 2 + LINQ2SQL, and a business layer so my UI doesnt interact with the DB directly. My question is this: In my MVC project, when bringing up views and passing around data, I still have to include my Data project for access to the classes in my Linq2Sql project. Is this correct? Example: Controller: ClassesRepository cr = new ClassesRepository(); // this is from my Business project Class classToEdit = cr.GetByClassId(id); // "Class" is from my data project I still have to reference the Class class in my linq2sql data project - shouldn't my UI be completely independent of my data layer? Or maybe I'm going about this all wrong.

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  • Method For Making Methods: Easy Ruby Metaprogramming

    - by yar
    I have a bunch of methods like this in view helper def background "#e9eaec" end def footer_link_color "#836448" end I'd like these methods exposed to the view, but I'd prefer the helper to be a bit more concise. What's the best way to turn a hash, say, into methods (or something else)?

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  • how can i download a set of variable images in flex/as3 and display them?

    - by james
    hi guys.... suppose i have 10 image variables like this var image1:String = http://somewhere.com/image1.jpg var image2:string = .....image2.jpg var image3:string = .....image3.jpg and so forth......... i have a timer that displays each variable as an image one a time .... how do i "buffer" the image and display them instead of going out each time the timer runs? im asking because sometimes the server could slow or some other reason. so what i want to do is to download all those images and then display them from the clients computer. some sort like @Embed ??? complete newbie.. so please go slow on me ... :p

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  • Match over multiple lines perl regular expression

    - by John
    Hi, I have a file like this: 01 00 01 14 c0 00 01 10 01 00 00 16 00 00 00 64 00 00 00 65 00 00 01 07 40 00 00 22 68 61 6c 2e 6f 70 65 6e 65 74 2e 63 6f 6d 3b 30 30 30 30 30 30 30 30 32 3b 30 00 00 00 00 01 08 40 00 00 1e 68 61 6c 2e 6f 70 65 6e 65 74 2d 74 65 6c 65 63 6f 6d 2e 6c 61 6e 00 00 00 00 01 28 40 00 00 21 72 65 61 6c 6d 31 2e 6f 70 65 6e 65 74 2d 74 65 6c 65 63 6f 6d 2e 6c 61 6e 00 00 00 00 00 01 25 40 00 00 1e 68 61 6c 2e 6f 70 65 6e 65 74 2d 74 65 6c 65 63 6f 6d 2e 6c 61 6e 00 00 00 00 01 1b 40 00 00 20 72 65 61 6c 6d 2e 6f 70 65 6e 65 74 2d 74 65 6c 65 63 6f 6d 2e 6c 61 6e 00 00 01 02 40 00 00 0c 01 00 00 16 00 00 01 a0 40 00 00 0c 00 00 00 01 00 00 01 9f 40 00 00 0c 00 00 00 00 00 00 01 16 40 00 00 0c 00 00 00 00 00 00 01 bb 40 00 00 28 00 00 01 c2 40 00 00 0c 00 00 00 00 00 00 01 bc 40 00 00 13 31 39 37 37 31 31 31 32 32 33 31 00 I am reading the file and then finding certain octets and replacing them with tags: while(<FH>){ $line =~ s/(00 00 00 64)/<incr4> /g; $line =~ s/(00 00 00 65)/<incr4> /g; $line =~ s/(30 30 30 30 30 32)/<incr6ascii:999999:0>/g; $line =~ s/(31 31 32 32 33 31)/<incr6ascii:999999:0>/g; print OUTPUT $line; # } So for example, 00 00 00 64 would be replaced by the tag. This was working fine, but it doesn't seem to able to match over multiple lines any more. For example the pattern 31 31 32 32 33 31 runs over multiple lines, and the regular expression doesn't seem to catch it. I tried using /m /s pattern modifiers to ignore new lines but they didn't match it either. The only way around it I can come up with, is to read the whole file into a string using: undef $/; my $whole_file = <FH>; my $line = $whole_file; $line =~ s/(00 00 00 64)/<incr4> /g; $line =~ s/(00 00 00 65)/<incr4> /g; $line =~ s/(30 30 30 30 30 32)/<incr6ascii:999999:0>/g; $line =~ s/(31 31 32 32 33 31)/<incr6ascii:999999:0>/g; print OUTPUT $line; This works, the tags get inserted correctly, but the structure of the file is radically altered. It is all dumped out on a single line. I would like to retain the structure of the file as it appears here. Any ideas as to how I might do this? /john

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  • Prevent SQL injection from form-generated SQL.

    - by Markos Fragkakis
    Hi all, I have a search table where user will be able to filter results with a filter of the type: Field [Name], Value [John], Remove Rule Field [Surname], Value [Blake], Remove Rule Field [Has Children], Value [Yes], Remove Rule Add Rule So the user will be able to set an arbitrary set of filters, which will result essentially in a completely dynamic WHERE clause. In the future I will also have to implement more complicated logical expressions, like Where (name=John OR name=Nick) AND (surname=Blake OR surname=Bourne), Of all 10 fields the user may or may not filter by, I don't know how many and which filters the user will set. So, I cannot use a prepared statement (which assumes that at least we know the fields in the WHERE clause). This is why prepared statements are unfortunately out of the question, I have to do it with plain old, generated SQL. What measures can I take to protect the application from SQL Injection (REGEX-wise or any other way)?

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  • Small utilities useful while programming [closed]

    - by subSeven
    What small and cool applications that can be helpful for programmer do you know ? I think about programs that not very famous. I know three: http://advsys.net/ken/download.htm EvalDraw - for protoyping games http://www.drpetter.se/project_sfxr.html sfxr - for makeing sound http://www.kloonigames.com/blog/general/timelog timelog - for mangament time of project

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  • Efficiency of while(true) ServerSocket Listen

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

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  • sql inner join problem

    - by Luke
    The following SQL query isn't working. I think the error is on the first line. SELECT SUBSTRING(tbl_news.comment, 1, 250) as tbl_news.comment, tbl_news.id, tbl_news.date, tbl_news.subject, tbl_users.username FROM tbl_news INNER JOIN tbl_users ON tbl_news.creator = tbl_users.id ORDER BY date DESC

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