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  • How do I ensure my abstract class's function can only operate on extenders of the same type as the c

    - by incrediman
    For example, let's say this is my abstract class: abstract class A{ int x; int y; void foo(A fooMe); } ...and B and C are two classes which extend A. What I want is for B to only be able to call foo() on other Bs, and for C to only be able to call foo() on other Cs. But I want this to be out of the hands of the programmer who's extending my A class - that is, I want a way to ensure this functionality within As code alone. What can I do? (If possible) I'd like to avoid any hack or generics solution that's too messy - I still want foo to be able to be called like this, for example: B b=new B(); B bb=new B(); bb.foo(b);

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  • The Scala way to use one actor per socket connection

    - by Stefan
    I am wondering how it is possible to avoid one socket connection pr. thread in Scala. I have thought a lot about it, but I always end up with some code which is listening for incoming data for each client connection. The problem is that I want to develop an application which should simultanously handle perhaps a couple of thousand connections. However I will of course not want to create a thread for each connection because of the lack of scalability and context switching. What would be the "right" way to do this. In my world it should be possible to have one actor for each connection without the need to block one thread per actor.

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  • returning values from function or method multiple times by only calling the class once

    - by Sokhrat Sikar
    I have a members.php file that shows my websites members. I echo members name by using foreach method. A method of Members class returns an array, then I use foreach loop in the members.php file to echo the members. I am trying to aovid writing php code in my members.php file. Is there a way to avoid using foreach inside members.php file? For example, is it possible to return value from a method couple of times? (by only calling the object once). Just like how we normally call the functions? This question doesn't make sense, but I am just trying to see if there is a away around this issue?

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  • How can I lock the cursor to the inside of a window on Linux?

    - by ZorbaTHut
    I'm trying to put together a game for Linux which involves a lot of fast action and flinging around of the mouse cursor. If the user wants to play in windowed mode, I'd quite like to lock the cursor to the inside of the window to avoid accidentally changing programs in the heat of battle (obviously this will cancel itself if the user changes programs or hits escape for the pause menu.) On Windows, this can be accomplished easily with ClipCursor(). I can't find an equivalent on Linux. Is there one? I plan to do this in pure X code, but obviously if anyone knows of a way to do this in any Linux windowing library then I can just read the source code and figure out how to duplicate it in X.

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  • Log4Perl - how to set exit code if any WARN, ERROR, or FATAL messages?

    - by pdxrlk
    Hi - I've been using Log4Perl extensively in a number of scripts. I'd like to augment those scripts to set an error code if any WARN or ERROR messages have been logged. I couldn't find any obvious way to do this based on existing documentation. I'd like to avoid a brute-force rewrite of my existing scripts to add a check on every WARN or ERROR log message; I'd prefer to handle it prior to script exit if possible like this pseudocode: if $log->has_warnings_or_errors then exit 1 else exit 0 Is there any easy way to call Log4Perl to determine if the current logger has issues messages of certain levels? Thanks.

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  • is vim able to detect in which language a file is written, and then load the correct dictionnary ?

    - by Niels
    I am using several languages, and by now I am obliged to indicate vim with which of these the spell check must be done. Is there a way to set up vim so that he automatically detects the correct one ? I remember vaguely that in a previous version of vim, when the spell check was not integrated, this was possible, using the vimspell script. It would be even better if this could apply not only to a file but also to a portion of a file, since I frequently mix several languages in a single file. Of course, I would like to avoid to load several dictionaries simultaneously.

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  • Mysterious different conversion to string[] of seemingly same input data

    - by Roman Kuzmin
    During investigation of some problem I found that the reason was unexpected different conversion to string[] of seemingly same input data. Namely, in the code below two commands both return the same two items File1.txt and File2.txt. But conversion to string[] gives different results, see the comments. Any ideas why is it? This might be a bug. If anybody also thinks so, I’ll submit it. But it would nice to understand what’s going on and avoid traps like that. # *** WARNING # *** Make sure you do not have anything in C:\TEMP\Test # *** The code creates C:\TEMP\Test with File1.txt, File2.txt # Make C:\TEMP\Test and two test files $null = mkdir C:\TEMP\Test -Force 1 | Set-Content C:\TEMP\Test\File1.txt 1 | Set-Content C:\TEMP\Test\File2.txt # This gets just file names [string[]](Get-ChildItem C:\TEMP\Test) # This gets full file paths [string[]](Get-ChildItem C:\TEMP\Test -Include *) # Output: # File1.txt # File2.txt # C:\TEMP\Test\File1.txt # C:\TEMP\Test\File2.txt

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  • overriding callbacks avoiding attribute pollution

    - by pygabriel
    I've a class that has some callbacks and its own interface, something like: class Service: def __init__(self): connect("service_resolved", self.service_resolved) def service_resolved(self, a,b c): ''' This function is called when it's triggered service resolved signal and has a lot of parameters''' the connect function is for example the gtkwidget.connect, but I want that this connection is something more general, so I've decided to use a "twisted like" approach: class MyService(Service): def my_on_service_resolved(self, little_param): ''' it's a decorated version of srvice_resolved ''' def service_resolved(self,a,b,c): super(MyService,self).service_resolved(a,b,c) little_param = "something that's obtained from a,b,c" self.my_on_service_resolved(little_param) So I can use MyService by overriding my_on_service_resolved. The problem is the "attributes" pollution. In the real implementation, Service has some attributes that can accidentally be overriden in MyService and those who subclass MyService. How can I avoid attribute pollution? What I've thought is a "wrapper" like approach but I don't know if it's a good solution: class WrapperService(): def __init__(self): self._service = service_resolved # how to override self._service.service_resolved callback? def my_on_service_resolved(self,param): ''' '''

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  • Replace html tag with a certain class

    - by fire
    I am looking for suitable replacement code that allows me replace the content inside of any HTML tag that has a certain class e.g. $class = "blah"; $content = "new content"; $html = '<div class="blah">hello world</div>'; // code to replace, $html now looks like: // <div class="blah">new content</div> Bare in mind that: It wont necessarily be a div, it could be <h2 class="blah"> The class can have more than one class and still needs to be replaced e.g. <div class="foo blah green">hello world</div> I am thinking regular expressions should be able to do this, if not I am open to other suggestions such as using the DOM class (although I would rather avoid this if possible because it has to be PHP4 compatible).

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  • html5 offline storage for Windows Mobile 6.1 or an alternative?

    - by SimonNet
    I understand that there are no browsers currently which support offline storage for mobile 6.1. I am trying to find a web form based solution avoiding the loss of data when my device has no connectivity. Have ruled out Gears and would like to avoid a win forms application as the forms change so often. Are there any other approaches that I should look at which are viable in C#? Are there any estimated dates for when we might see a browser for mobile 6.1 which can offer offline storage? Thanks

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  • 16 millisecond quantization when sending/receivingtcp packets

    - by MKZ
    Hi, I have a C++ application running on windows xp 32 system sending and receiving short tcp/ip packets. Measuring (accurately) the arrival time I see a quantization of the arrival time to 16 millisecond time units. (Meaning all packets arriving are at (16 )xN milliseconds separated from each other) To avoid packet aggregation I tried to disable the NAGLE algorithm by setting the IPPROTO_TCP option to TCP_NODELAY in the socket variables but it did not help I suspect that the problem is related to the windows schedular which also have a 16 millisecond clock.. Any idea of a solution to this problem ? Thanks

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  • Proper use of of typedef in C++

    - by dicroce
    I have coworkers who occasionally use typedef to avoid typing. For example: typedef std::list<Foobar> FoobarList; ... FoobarList GetFoobars(); Personally, I always hate coming across code like this, largely because it forces me to go lookup the typedef so I can tell how to use it. I also feel like this sort of thing is a potential slippery slope... If you do this, why aren't you doing it more? (pretty soon, your code is totally obfuscated). I found this SO question regarding this issue: when should I use typedef in C I have two questions: 1) am I truly alone in disliking this? 2) If the vast majority of people think this sort of typedef use is OK, what criteria do you use to determine whether to typedef a type?

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  • PHP 5.3 Namespaces should i use every PHP function with backslash?

    - by lhwparis
    Hi, im now using namespaces in PHP 5.3 now there is a fallback mechanism for functions which dont exist in the namespace. so php every time checks if the function exists in namespace and then tries to load it from global space. So what about all php internal functions? strstr for example? Should i now use every php internal function with a \ ? to avoid php first checking the namespace? is this fallback a huge performance drop? what do you think?

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  • Why do I have to give an identifier?

    - by Knowing me knowing you
    In code: try { System.out.print(fromClient.readLine()); } catch(IOException )//LINE 1 { System.err.println("Error while trying to read from Client"); } In code line marked as LINE 1 compiler forces me to give an identifier even though I'm not using it. Why this unnatural constrain? And then if I type an identifier I'm getting warning that identifier isn't used. It just doesn't make sense to me, forcing a programmer to do something unnecesarry and surplus. And after me someone will revise this code and will be wondering if I didn't use this variable on purpouse or I just forgot. So in order to avoid that I have to write additional comment explaining why I do not use variable which is unnecessary in my code. Thanks

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  • Help getting PHP sessions to persist after being taken off-site

    - by Rob
    Hi, we're working on a payment gateway system with PHP. We use sessions to store the shopping cart data. The system takes you off-site to the payment processor's site, and then return you to your site. On most hosts, we have no issues when we arrive back at our site and having the session data still be there. On those with an issue, turning off the PHP session referer_check has worked in the past. We don't really want to have to include the PHPSESSID as a GET variable, and hope to avoid that. What I'm looking for is what other server configurations would cause the session to be killed, and any other workarounds there might be. Thanks for your help.

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  • SWIG interface file questions

    - by morpheous
    I am writing a C/C++ extension module for other languages and I am using SWIG to generate the bindings. I have two questions Can I include more than 1 header file in the declaration part of the interface file e.g.: /* Declarations exposed to wrapper: */ > %{ > #define SWIG_FILE_WITH_INIT > #include "a.h" > #include "b.h" > #include "c.h" %} In all of the examples I have seen so far, after the header include declaration (as shown above), the functions declared in the header are then declared again in the interface file. Is this really necessary, as it means there are two copies of the function declarations that need to be maintained. Note: I can appreciate that some functions/methods declaration may need to be 'decorated' with the 'newobject' declaration so these obviously need to be in the interface file, to avoid memory leaks - however, I would have though that it would be sufficient to include the headers and then ONLY the declarations of the functions/methods that need to be declared with 'newobject' - is this recommended way of doing things?

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  • delete all records except the id I have in a python list

    - by jay_t
    Hi all, I want to delete all records in a mysql db except the record id's I have in a list. The length of that list can vary and could easily contain 2000+ id's, ... Currently I convert my list to a string so it fits in something like this: cursor.execute("""delete from table where id not in (%s)""",(list)) Which doesn't feel right and I have no idea how long list is allowed to be, .... What's the most efficient way of doing this from python? Altering the structure of table with an extra field to mark/unmark records for deletion would be great but not an option. Having a dedicated table storing the id's would indeed be helpful then this can just be done through a sql query... but I would really like to avoid these options if possible. Thanks,

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  • How to add a web service reference in a DLL

    - by dan
    I'm creating a DLL with a reference to web services (I don't have the choice to do so) but I have to add web service references to the project that uses the DLL for it to work. Example, I have the DLL called API.DLL that calls a web service called WebService.svc that I want to use in a project called WinForm. First, I have to add a "Service Reference" to WebService.svc in API.DLL. Then, I add a reference API.DLL to WinForm but it doesn't work unless I also add a service reference to WebService.svc in WinForm. What can I do to avoid that last step?

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  • Why can't I enforce derived classes to have parameterless constructors?

    - by FrisbeeBen
    I am trying to do the following: public class foo<T> where T : bar, new() { public foo() { _t = new T(); } private T _t; } public abstract class bar { public abstract void someMethod(); // Some implementation } public class baz : bar { public overide someMethod(){//Implementation} } And I am attempting to use it as follows: foo<baz> fooObject = new foo<baz>(); And I get an error explaining that 'T' must be a non-abstract type with a public parameterless constructor in order to use it as parameter 'T' in the generic type or method. I fully understand why this must be, and also understand that I could pass a pre-initialized object of type 'T' in as a constructor argument to avoid having to 'new' it, but is there any way around this? any way to enforce classes that derive from 'bar' to supply parameterless constructors?

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  • Override decimal ToString() method

    - by Jimbo
    I have a decimal datatype with a precision of (18, 8) in my database and even if its value is simply 14.765 it will still get displayed as 14.76500000 when I use Response.Write to return its value into a webpage. Is it possible to override its default ToString method to return the number in the format #,###,##0.######## so that it only displays relevant decimal places? UPDATE I'm assuming that when one outputs number on a page like <%= item.price %> (where item.price is a number) that the number's ToString method is being called? I'm trying to avoid having to change every instance where the value is displayed by defaulting the ToString() format somehow.

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  • Split query result by half in TSQL (obtain 2 resultsets/tables)

    - by rubdottocom
    I have a query that returns a large number of heavy rows. When I transform this rows in a list of CustomObject I have a big memory peak, and this transformation is made by a custom dotnet framework that I can't modify. I need to retrieve a less number of rows to do "the transform" in two passes and then avoid the momery peak. How can I split the result of a query by half? I need to do it in DB layer. I thing to do a "Top count(*)/2" but how to get the other half? Thank you!

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  • WPF Logical Tree - bottom up vs. top down

    - by Dor Rotman
    Hello, I've read the MSDN article about the layouts pass, that states: When a node is added or removed from the logical tree, property invalidations are raised on the node's parent and all its children. As a result, a top-down construction pattern should always be followed to avoid the cost of unnecessary invalidations on nodes that have already been validated. Now lets assume I do this. Won't the users see the control tree populate itself and the layout change several times during the control creation process? I want the whole control tree to just appear completely full. Thanks!

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  • Scheduling a visual studio load test using powershell giving me BSOD

    - by user952342
    I have a visual studio load test which I want to run every hour so that I can start to collect some data. To do this, I thought it would be best to make a little powershell script and put a command like this inside: Invoke-Expression -command "& '$env:VS100COMNTOOLS..\IDE\mstest.exe' /testcontainer:"C:\Users\benb\Documents\Visual Studio 2010\Projects\BBPerformanceTest\bin\Debug\HomePageOnly.loadtest"" That command works fine, but sometimes when its run I get a blue screen of death. However, when I run my load test through the visual studio GUI, I never get a BSOD. two questions: is it possible to avoid this BSOD? Is there another way I can schedule my load test? Thanks

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  • Remove margin between rows of overflowing inline elements

    - by Ian
    I'm creating a tile-based game and am using block rendering to update a large list of tiles. I'm attempting to do this in the most simple manner, so I've been trying to work with HTML's default layouts. Right now I'm creating 'inline-blocks', omitting whitespace between the elements to avoid horizontal spaces in between them but when the blocks overflow and create a new line there is some vertical margining in which I do not know how to remove. Example to make this a bit clearer: http://jsfiddle.net/mLa93/13/ (Pretty much I just need to remove the spacing between the block rows while retaining the simple markup.)

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  • How Do I Execute A Stored Procedure From A BizTalk SendPort?

    - by kgarske
    Hello, I would like to call a stored procedure from a SendPort. I want to avoid an orchestration and instead, create a subscription to the message box based on the receive port and message type. I also need to use attributes from the received message xml as parameters for my stored procedure. My assumption is that I should use WCF-SQL adapter. However, the only examples I have found require a 20 step process and some magic/luck... oh yeah, and an orchestration. Am I crazy for thinking this should be way simpler than it seems? Can anyone provide me with resources or advice?

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