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• database row/ record pointers

  - by David

  Hi I don't know the correct words for what I'm trying to find out about and as such having a hard time googling. I want to know whether its possible with databases (technology independent but would be interested to hear whether its possible with Oracle, MySQL and Postgres) to point to specific rows instead of executing my query again. So I might initially execute a query find some rows of interest and then wish to avoid searching for them again by having a list of pointers or some other metadata which indicates the location on a database which I can go to straight away the next time I want those results. I realise there is caching on databases, but I want to keep these "pointers" else where and as such caching doesn't ultimately solve this problem. Is this just an index and I store the index and look up by this? most of my current tables don't have indexes and I don't want the speed decrease that sometimes comes with indexes. So whats the magic term I've been trying to put into google? Cheers

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• How compiling circular dependencies works?

  - by Fabio F.

  I've made the example in Java but I think (not tested) that it works in other (all?) languages. You have 2 files M.java that says public class MType{ XType x; MType(){ x = null;} } and another file XType.java (in the same directory) public class XType{ MType m; public XType(MType m){ this.m=m;} } Ok it's BAD programming , but.. if you run javac XType it compiles: compiles even MTypes because XType needs it. But.. MType needs XType.. how it works? How does the compiler know what is happening? Probably is a stupid question, but I would like to know how the compiler (javac or other compilers if you know.) manages that situation, not how to avoid it. I'm asking because i'm writing a precompiler and I would like to manage that situation.. Thank you

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• Can using non primitive Integer/ Long datatypes too frequently in the application, hurt the performance??

  - by Marcos

  I am using Long/Integer data types very frequently in my application, to build Generic datatypes. I fear that using these wrapper objects instead of primitive data types may be harmful for performance since each time it needs to create objects which is an expensive operation. but also it seems that I have no other choice(when I have to use primtives with generics) rather than just using them. However, still it would be great if you can suggest if there is anything I could do to make it better. or any way if I could just avoid it ?? Also What may be the downsides of this ? Suggestions welcomed!

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• How to solve this Java type safety warning? (Struts2)

  - by Nicolas Raoul

  Map session = ActionContext.getContext().getSession(); session.put("user", user); This code generates a warning: Type safety: The method put(Object, Object) belongs to the raw type Map. References to generic type Map should be parameterized. Map<String, Serializable> session = (Map<String, Serializable>)ActionContext.getContext().getSession(); session.put("user", user); This code generates a warning: Type safety: Unchecked cast from Map to Map. The getSession method belongs to Struts2 so I can't modify it. I would like to avoid using @SuppressWarnings because other warnings can be useful. I guess all Struts2 users in the world faced the same problem... is there an elegant solution?

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• Status corresponding to Minimum value

  - by Lijo

  Hi Team, I am using SQL Server 2005. I have a table as given below. There can be multiple cancellations for each FundingID. I want to select the FundingCancellationReason corrersponding to minimum date for each funding. I wrote a query as follows. It is an SQL error 1) Could you please help me to avoid the SQL Error? 2) Is there any better logic to achieve the same? CREATE TABLE #FundingCancellation( [FundingCancellationID] INT IDENTITY(1,1) NOT NULL, [FundingID] INT , FundingCancellationDt SMALLDATETIME , FundingCancellationReason VARCHAR(50) ) SELECT FundingID, MIN(FundingCancellationDt), ( SELECT FundingCancellationReason FROM #FundingCancellation FC2 WHERE FC1.FundingID = FC2.FundingID AND FC2.FundingCancellationDt = MIN(FundingCancellationDt) ) [Reason Corresponding Minimum Date] FROM #FundingCancellation FC1 GROUP BY FundingID -- An aggregate may not appear in the WHERE clause unless it is in a subquery contained in a HAVING clause or a select list, and the column being aggregated is an outer reference. I have seen the similar approach working in a somewhat complex query. So I believe tehre will be a way to correct my query Thanks Lijo

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• Passing message over network

  - by Sylvestre Equy

  Hi, I'm currently trying to develop a message-oriented networking framework and I'm a bit stuck on the internal mechanism. Here are the problematic interfaces : public interface IMessage { } public class Connection { public void Subscribe<TMessage>(Action<TMessage> messageCallback); public void Send<TMessage>(TMessage message); } The Send method does not seem complicated, though the mechanism behind Subscribe seems a bit more painful. Obviously when receiving a message on one end of the connection, I'll have to invoke the appropriate delegate. Do you have any advice on how to read messages and easily detect their types ? By the way, I'd like to avoid to use MSMQ.

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• Javascript object encapsulation that tracks changes

  - by Raynos

  Is it possible to create an object container where changes can be tracked Said object is a complex nested object of data. (compliant with JSON). The wrapper allows you to get the object, and save changes, without specifically stating what the changes are Does there exist a design pattern for this kind of encapsulation Deep cloning is not an option since I'm trying to write a wrapper like this to avoid doing just that. The solution of serialization should only be considered if there are no other solutions. An example of use would be var foo = state.get(); // change state state.update(); // or state.save(); client.tell(state.recentChange()); A jsfiddle snippet might help : http://jsfiddle.net/Raynos/kzKEp/ It seems like implementing an internal hash to keep track of changes is the best option. [Edit] To clarify this is actaully done on node.js on the server. The only thing that changes is that the solution can be specific to the V8 implementation.

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• How can I configure a Hudson job to use a specific JDK?

  - by rewbs

  I have a number of projects running on a Hudson slave. I'd like one of them to run Ant under Java6, rather than the default (which is Java5 in my environment). In the project configuration view, I was hoping to find either: An explicit option allowing me to set a custom JDK location to use for this project. A way to set custom environment variables for this project, which would allow me to set JAVA_HOME to the JDK6 location. The would make Ant pick up and run on Java6 as desired. Is there a way to do either of the above? If one of those facilities is available, I can't see how to access it. I'm running on Hudson 1.285. I would rather avoid using an "execute shell" operation instead of the "invoke Ant" operation if possible: my slave is on z/OS and Hudson doesn't seem to create the temporary shell scripts properly on this platform (probably an encoding issue).

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• Return from parent sub in Perl

  - by JS Bangs

  I want to write a subroutine which causes the caller to return under certain conditions. This is meant to be used as a shortcut for validating input to a function. What I have so far is: sub needs($$) { my ($condition, $message) = @_; if (not $condition) { print "$message\n"; # would like to return from the *parent* here } return $condition; } sub run_find { my $arg = shift @_; needs $arg, "arg required" or return; needs exists $lang{$arg}, "No such language: $arg" or return; # etc. } The advantage of returning from the caller in needs would then be to avoid having to write the repetitive or return inside run_find and similar functions.

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• Is it possible to use RedirectToAction() inside a custom AuthorizeAttribute class?

  - by Lance McNearney

  Using ASP.Net MVC 2, is there any way to use the RedirectToAction() method of the Controller class inside a class that is based on the AuthorizeAttribute class? public class CustomAttribute : AuthorizeAttribute { protected override bool AuthorizeCore(HttpContextBase context) { // Custom authentication goes here return false; } public override void OnAuthorization(AuthorizationContext context) { base.OnAuthorization(context); // This would be my ideal result context.Result = RedirectToAction("Action", "Controller"); } } I'm looking for a way to re-direct the user to a specific controller / action when they fail the authentication instead of returning them to the login page. Is it possible to have the re-direct URL generated for that controller / action and then use RedirectResult()? I'm trying to avoid the temptation to just hard-code the URL.

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• Library for Dataflow in C

  - by msutherl

  How can I do dataflow (pipes and filters, stream processing, flow based) in C? And not with UNIX pipes. I recently came across stream.py. Streams are iterables with a pipelining mechanism to enable data-flow programming and easy parallelization. The idea is to take the output of a function that turns an iterable into another iterable and plug that as the input of another such function. While you can already do this using function composition, this package provides an elegant notation for it by overloading the operator. I would like to duplicate a simple version of this kind of functionality in C. I particularly like the overloading of the operator to avoid function composition mess. Wikipedia points to this hint from a Usenet post in 1990. Why C? Because I would like to be able to do this on microcontrollers and in C extensions for other high level languages (Max, Pd*, Python). * (ironic given that Max and Pd were written, in C, specifically for this purpose – I'm looking for something barebones)

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• Detect if an assembly is available

  - by jgaa

  I'm implementing an installer in Java, that is supposed to download and install an application for non-privileged users in Windows (from XP and up). The application is written in C++, and depend on the usual VC runtime-libraries (msvcm90.dll and friends). In order to save bandwidth, I want to avoid downloading the VC redistributables if they already are available for the user. I do however have a problem finding a reliable method to detect if an assembly is installed. If the assembly is missing, I will deploy it as described here: http://msdn.microsoft.com/en-us/library/ms235291%28VS.80%29.aspx So the question is simply how to detect if a (any) assembly is installed on the machine. It's no requirement that this can be done from Java. I can easily write a small probe in C++ and link it statically for the task. jgaa

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• Is there a way to cause a new C++ class instance to fail, if certain conditions in the contructor ar

  - by Jim Fell

  As I understand it, when a new class is instantiated in C++, a pointer to the new class is returned, or NULL, if there is insufficient memory. I am writing a class that initializes a linked list in the constructor. If there is an error while initializing the list, I would like the class instantiator to return NULL. For example: MyClass * pRags = new MyClass; If the linked list in the MyClass constructor fails to initialize properly, I would like pRags to equal NULL. I know that I can use flags and additional checks to do this, but I would like to avoid that, if possible. Does anyone know of a way to do this? Thanks.

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• Insert into ... Select *, how to ignore identity?

  - by Haoest

  I have a temp table with the exact structure of a concrete table T. It was created like this: select top 0 * into #tmp from T After processing and filling in content into #tmp, I want to copy the content back to T like this: insert into T select * from #tmp This is okay as long as T doesn't have identity column, but in my case it does. Is there anyways I can ignore the auto-increment identity column from #tmp when I copy to T? My motivation is to avoid having to spell out every column name in the Insert Into list. EDIT: toggling identity_insert wouldn't work because the pkeys in #tmp may collide with those in T if rows were inserted into T outside of my script, that's if #tmp has auto-incremented the pkey to sync with T's in the first place.

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• How can I force a subscriber to be synchronized from a local snapshot?

  - by Brian

  Hello, I have a SQL 2005 server replicating(merge\push) to SQL 2005 and SQL 2000 servers. I have multiple subscribers spread througout the United states. I have set , @snapshot_in_defaultfolder = N'false', @alt_snapshot_folder = N'c:\snapshots\Merge\' (sample location). I take the snapshot from the publisher that is in the same location, 'c:\snapshots\Merge\', and copy it to the subscribers. I wanted to avoid applying the snapshot over the WAN but from the performance I am getting the synchronization is going over the WAN. Does anybody have any ideas how to make sure that I am using the local copy of the snapshot and not the copy at the publisher? Thanks

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• Java Instance of: Supertypes and Subtypes seem to be equal? How to test exactly for Type?

  - by jens

  I need to test, if an instance is exactly of a given type. But it seems that instanceof returns true also if the subtype is tested for the supertype (case 3). I never knew this before and I am quite surprised. Am I doing something wrong here? How do I exactly test for a given type? //.. class DataSourceEmailAttachment extends EmailAttachment //... EmailAttachment emailAttachment = new EmailAttachment(); DataSourceEmailAttachment emailAttachmentDS = new DataSourceEmailAttachment(); if (emailAttachment instanceof EmailAttachment){ System.out.println(" 1"); } if (emailAttachment instanceof DataSourceEmailAttachment){ System.out.println(" 2"); } if (emailAttachmentDS instanceof EmailAttachment){ System.out.println(" 3 "); } if (emailAttachmentDS instanceof DataSourceEmailAttachment){ System.out.println(" 4"); } RESULT: 1 3 4 I want to avoid case 3, I only want "exact matches" (case 1 and 4) how do I test for them?

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• Accessing php $_SESSION from python (wsgi) - is it possible?

  - by Bill Zimmerman

  Hi, I've got a python/WSGI app which needs to check to see if a user has logged on to a PHP web app. The problem is that the PHP app checks if a user has logged on by comparing a value in the $_SESSION variable to a value in the cookie from the user's browser. I would prefer to avoid changing the behavior of the php app if at all possible. My questions: Is there anyway I can access the session variables from within python? Where should I start to look? Are there any obvious security/performance issues I should be aware of when taking this approach?

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• UITableView with contact image problems.

  - by prathumca

  As par my app requirement, I'm showing the contact images in a UITableView as shown below. ABRecordRef contact = [self getContact]; if(contact && ABPersonHasImageData(contact)) { UIImage *contactImage = [UIImage imageWithData:(NSData*)ABPersonCopyImageData(contact)]; callImage.image = contactImage; } I've two problems if I use the above code segment. Table Scrolling is too slow. If comment the above code, then UITable responds very fast. Memory Management. My app started using 25 - 30 MB of RAM. Is there any better way to avoid the above two problems?

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• Jquery Accordion and multiple slideshows

  - by Dipesh Parmar

  I've been using a lot of slideshows recently on my sites and one thing thats puzzled me is using more than one slideshow per page. I'm currently working on my own site, experimenting with Jquery Accordion. I've managed to adopt a very simple javascript slideshow, see below: http://dvpwebdesign.com/test/accordion/blank.html However i'm unable to either incorporate or use a different multiple slideshow plugin. I dont need slideshow navigation, so the The Cycle plugin works really well and i know you can use multiple slideshows. But if i either use Cycle alongside the current javascript slideshow, or only use the Cycle slideshow to avoid any possible conflict, the Accordion menu stops working. I just cant see what i am doing wrong, can anyone help?

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• Syncronizing indices of function pointer table to table contents

  - by Thomas Matthews

  In the embedded system I'm working on, we are using a table of function pointers to support proprietary Dynamic Libraries. We have a header file that uses named constants (#define) for the function pointer indices. These values are used in calculating the location in the table of the function's address. Example: *(export_table.c)* // Assume each function in the table has an associated declaration typedef void (*Function_Ptr)(void); Function_Ptr Export_Function_Table[] = { 0, Print, Read, Write, Process, }; Here is the header file: *export_table.h* #define ID_PRINT_FUNCTION 1 #define ID_READ_FUNCTION 2 #define ID_WRITE_FUNCTION 3 #define ID_PROCESS_FUNCTION 4 I'm looking for a scheme to define the named constants in terms of their location in the array so that when the order of the functions changes, the constants will also change. (Also, I would like the compiler or preprocessor to calculate the indices to avoid human mistakes like typeo's.)

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• How do you escape parentheses in a Binding indexer

  - by Chris S

  I have the following XAML: <Grid x:Name="LayoutRoot" Background="White" DataContext="{Binding Source={StaticResource MyDataKey}}"> <TextBox Name="_myId" Text="{Binding MyDictionary[(Textbox.Name)]" /> </Grid> But it thinks the key in my dictionary is called "(Textbox.Name)", instead of "_myId". The format below works, where I have a property in my class called "_myId": <TextBox Name="_myId" Text="{Binding (Textbox.Name)" /> I've tried using ^ and \ to escape the brackets. Is this syntax supported? I'm trying to avoid duplication of the name in two attributes.

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• Fatal error: Cannot use string offset as an array

  - by learner

  Array ( [0] = Array ( [auth_id] = 1 [auth_section] = Client Data Base [auth_parent_id] = 0 [auth_admin] = 1 [sub] = Array ( [0] = Array ( [auth_id] = 2 [auth_section] = Client Contact [auth_parent_id] = 1 [auth_admin] = 1 ) ) ) [1] => Array ( [auth_id] => 6 [auth_section] => All Back Grounds [auth_parent_id] => 0 [auth_admin] => ,4 [sub] => Array ( [0] => Array ( [auth_id] => 7 [auth_section] => Edit Custom [auth_parent_id] => 6 [auth_admin] => 1 ) ) ) [2] => Array ( [auth_id] => 20 [auth_section] => Order Mail [auth_parent_id] => 0 [auth_admin] => 1 [sub] => ) } When I process the sub inner array it shows this error how can I avoid that :)

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• c++ polymorphism and other function question

  - by aharont

  i have got this code: class father{ public: virtual void f() { cout<<1;} }; class son:public father{ public: void f() {cout<<2;} }; void test (father x){x.f();} int main(){ son s; test(s); } the question says: the output is '1', what is the rule about polymorphism that the programmer forgot and how can i fix it so the output would be '2'? there is another rule that the programmer forgot when he wrote the father class, and he need to add an empty function to avoid problems from other sons of the father class. what is the rule and what is the missing function? another question write the g function so the next code would run with no crashes int x=11; g(x)=22;

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• Jquery function calls more than one time.

  - by Harie

  I am having an aspx page in which I am calling a user control. The user control I am using a pop up to display it when a user clicks a asp:linkbutton. In that user control I am having a textbox and I am calling a Jquery Blur to do some validation. While doing so the function is calling [blur] is calling twice. I just called an alert() with the textbox value.So I can see the alert is coming twice .What I need to do to avoid the second time. I need to do it only whenever the user going out of the textbox and that also one time. $('#<%=txtCategory.ClientID %>').blur(function() { alert($(this).val()); }); This is called twice.Thanks for ur response.

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• Can I have fixed typed ArrayList in C#, just like C++?

  - by Kazoom

  I have an ArrayList which contains fixed type of objects. However everytime I need to extract an object a particular index, I need to typecast it to my user defined type from object type. Is there a way in C# to declare ArrayList of fixed types just like Java and C++, or is there a work around to avoid the typecasting everytime? Edit: I apologize I forgot mentioning that I require the datastructure to be thread-safe, which List is not. Otherwise I would have just used a normal Array. But I want to save myself from the effort of explicitly locking and unlocking while writing the array. So I thought of using ArrayList, synchronize it, but it requires typecasting every time.

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