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  • Can the Perl compiler tell me if I have an unchecked exception in my code?

    - by Konerak
    Is there a way in Perl to declare that a method can throw an error (or die)? EDIT: What interests me the most is a way to get the compiler or IDE to tell me I have an unchecked exception somewhere in my code. I always loved how in Java, a method could handle an Exception and/or throw it. The method signature allows to put "throws MyException", so a good IDE/compiler would know that if you use said method somewhere in your code, you'd have to check for the Exception or declare your function to "throws" the Exception further. I'm unable to find something alike in Perl. A collegue of mine wrote a method which "dies" on incorrect input, but I forget to eval-if($@) it... offcourse the error was only discovered while a user was running the application. (offcourse I doubt if there is any existing IDE that could find these kind of things for Perl, but atleast perl -cw should be able to, no?)

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  • Like Html.RenderAction() but without reinstantiating the controller object

    - by Jørn Schou-Rode
    I like to use the RenderAction extension method on the HtmlHelper object to render sidebars and the like in pages, as it allows me to keep the data access code for each such part in separate methods on the controller. Using an abstract controller base, I can define a default "sidebar strategy", which can then be refined by overriding the method in a concrete controller, when needed. The only "problem" I have with this approach, is that the RenderAction is built in a way where it always creates a news instance of the controller class, even when rendering actions from the controller already in action. Some of my controllers does some data lookup in their Initialize method, and using the RenderAction method in the view causes this to occur several times in the same request. Is there some alternative to RenderAction which will reuse the controller object if the action method to be invoked is on the same controller class as the "parent" action?

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  • Another ArrayIndexOutOfBoundsException in ListView

    - by synic
    This one is different than the other one I posted. Any ideas? java.lang.IndexOutOfBoundsException: Invalid location 14, size is 1 at java.util.ArrayList.get(ArrayList.java:341) at android.widget.HeaderViewListAdapter.getView(HeaderViewListAdapter.java:188) at android.widget.AbsListView.obtainView(AbsListView.java:1256) at android.widget.ListView.makeAndAddView(ListView.java:1668) at android.widget.ListView.fillUp(ListView.java:667) at android.widget.ListView.fillGap(ListView.java:613) at android.widget.AbsListView.trackMotionScroll(AbsListView.java:2531) at android.widget.AbsListView$FlingRunnable.run(AbsListView.java:2353) at android.os.Handler.handleCallback(Handler.java:587) at android.os.Handler.dispatchMessage(Handler.java:92) at android.os.Looper.loop(Looper.java:123) at android.app.ActivityThread.main(ActivityThread.java:4595) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:521) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) at dalvik.system.NativeStart.main(Native Method)

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  • How to get a handle/reference to the current controller object inside a rails functional test?

    - by Dave Paroulek
    I must be missing something very simple, but can't find the answer to this. I have a method named foo inside bar_controller. I simply want to call that method from inside a functional test. Here's my controller: class BarsController < ApplicationController def foo # does stuff end end Here's my functional test: class BarsControllerTest << ActionController::TestCase def "test foo" do # run foo foo # assert stuff end end When I run the test I get: NameError: undefined local variable or method `foo' for #<BarsControllerTest:0x102f2eab0> All the documentation on functional tests describe how to simulate a http get request to the bar_controller which then runs the method. But I'd just like to run the method without hitting it with an http get or post request. Is that possible? There must be a reference to the controller object inside the functional test, but I'm still learning ruby and rails so need some help.

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  • Using Delegates in C# (Part 1)

    - by rajbk
    This post provides a very basic introduction of delegates in C#. Part 2 of this post can be read here. A delegate is a class that is derived from System.Delegate.  It contains a list of one or more methods called an invocation list. When a delegate instance is “invoked” with the arguments as defined in the signature of the delegate, each of the methods in the invocation list gets invoked with the arguments. The code below shows example with static and instance methods respectively: Static Methods 1: using System; 2: using System.Linq; 3: using System.Collections.Generic; 4: 5: public delegate void SayName(string name); 6: 7: public class Program 8: { 9: [STAThread] 10: static void Main(string[] args) 11: { 12: SayName englishDelegate = new SayName(SayNameInEnglish); 13: SayName frenchDelegate = new SayName(SayNameInFrench); 14: SayName combinedDelegate =(SayName)Delegate.Combine(englishDelegate, frenchDelegate); 15: 16: combinedDelegate.Invoke("Tom"); 17: Console.ReadLine(); 18: } 19: 20: static void SayNameInFrench(string name) { 21: Console.WriteLine("J'ai m'appelle " + name); 22: } 23: 24: static void SayNameInEnglish(string name) { 25: Console.WriteLine("My name is " + name); 26: } 27: } We have declared a delegate of type SayName with return type of void and taking an input parameter of name of type string. On line 12, we create a new instance of this delegate which refers to a static method - SayNameInEnglish.  SayNameInEnglish has the same return type and parameter list as the delegate declaration.  Once a delegate is instantiated, the instance will always refer to the same target. Delegates are immutable. On line 13, we create a new instance of the delegate but point to a different static method. As you may recall, a delegate instance encapsulates an invocation list. You create an invocation list by combining delegates using the Delegate.Combine method (there is an easier syntax as you will see later). When two non null delegate instances are combined, their invocation lists get combined to form a new invocation list. This is done in line 14.  On line 16, we invoke the delegate with the Invoke method and pass in the required string parameter. Since the delegate has an invocation list with two entries, each of the method in the invocation list is invoked. If an unhandled exception occurs during the invocation of one of these methods, the exception gets bubbled up to the line where the invocation was made (line 16). If a delegate is null and you try to invoke it, you will get a System.NullReferenceException. We see the following output when the method is run: My name is TomJ'ai m'apelle Tom Instance Methods The code below outputs the same results as before. The only difference here is we are creating delegates that point to a target object (an instance of Translator) and instance methods which have the same signature as the delegate type. The target object can never be null. We also use the short cut syntax += to combine the delegates instead of Delegate.Combine. 1: public delegate void SayName(string name); 2: 3: public class Program 4: { 5: [STAThread] 6: static void Main(string[] args) 7: { 8: Translator translator = new Translator(); 9: SayName combinedDelegate = new SayName(translator.SayNameInEnglish); 10: combinedDelegate += new SayName(translator.SayNameInFrench); 11:  12: combinedDelegate.Invoke("Tom"); 13: Console.ReadLine(); 14: } 15: } 16: 17: public class Translator { 18: public void SayNameInFrench(string name) { 19: Console.WriteLine("J'ai m'appelle " + name); 20: } 21: 22: public void SayNameInEnglish(string name) { 23: Console.WriteLine("My name is " + name); 24: } 25: } A delegate can be removed from a combination of delegates by using the –= operator. Removing a delegate from an empty list or removing a delegate that does not exist in a non empty list will not result in an exception. Delegates are invoked synchronously using the Invoke method. We can also invoke them asynchronously using the BeginInvoke and EndInvoke methods which are compiler generated.

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  • Lazy loading of child throwing session error

    - by Thomas Buckley
    I'm the following error when calling purchaseService.updatePurchase(purchase) inside my TagController: SEVERE: Servlet.service() for servlet [PurchaseAPIServer] in context with path [/PurchaseAPIServer] threw exception [Request processing failed; nested exception is org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.app.model.Purchase.tags, no session or session was closed] with root cause org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.app.model.Purchase.tags, no session or session was closed at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:383) at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:375) at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:368) at org.hibernate.collection.PersistentSet.add(PersistentSet.java:212) at com.app.model.Purchase.addTags(Purchase.java:207) at com.app.controller.TagController.createAll(TagController.java:79) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:212) at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:126) at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:96) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:617) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:578) at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:900) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:827) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882) at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:789) at javax.servlet.http.HttpServlet.service(HttpServlet.java:641) at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:999) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:565) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:309) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:662) TagController: @RequestMapping(value = "purchases/{purchaseId}/tags", method = RequestMethod.POST, params = "manyTags") @ResponseStatus(HttpStatus.CREATED) public void createAll(@PathVariable("purchaseId") final Long purchaseId, @RequestBody final Tag[] entities) { Purchase purchase = purchaseService.getById(purchaseId); Set<Tag> tags = new HashSet<Tag>(Arrays.asList(entities)); purchase.addTags(tags); purchaseService.updatePurchase(purchase); } Purchase: @Entity @XmlRootElement public class Purchase implements Serializable { /** * */ private static final long serialVersionUID = 6603477834338392140L; @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; @OneToMany(mappedBy = "purchase", fetch = FetchType.LAZY, cascade={CascadeType.ALL}) private Set<Tag> tags; @JsonIgnore public Set<Tag> getTags() { if (tags == null) { tags = new LinkedHashSet<Tag>(); } return tags; } public void setTags(Set<Tag> tags) { this.tags = tags; } ... } Tag: @Entity @XmlRootElement public class Tag implements Serializable { /** * */ private static final long serialVersionUID = 5165922776051697002L; @Id @GeneratedValue(strategy = GenerationType.AUTO) private Long id; @ManyToOne(fetch = FetchType.LAZY) @JoinColumns({@JoinColumn(name = "PURCHASEID", referencedColumnName = "ID")}) private Purchase purchase; @JsonIgnore public Purchase getPurchase() { return purchase; } public void setPurchase(Purchase purchase) { this.purchase = purchase; } } PurchaseService: @Service public class PurchaseService implements IPurchaseService { @Autowired private IPurchaseDAO purchaseDAO; public PurchaseService() { } @Transactional public List<Purchase> getAll() { return purchaseDAO.findAll(); } @Transactional public Purchase getById(Long id) { return purchaseDAO.findOne(id); } @Transactional public void addPurchase(Purchase purchase) { purchaseDAO.save(purchase); } @Transactional public void updatePurchase(Purchase purchase) { purchaseDAO.update(purchase); } } TagService: @Service public class TagService implements ITagService { @Autowired private ITagDAO tagDAO; public TagService() { } @Transactional public List<Tag> getAll() { return tagDAO.findAll(); } @Transactional public Tag getById(Long id) { return tagDAO.findOne(id); } @Transactional public void addTag(Tag tag) { tagDAO.save(tag); } @Transactional public void updateTag(Tag tag) { tagDAO.update(tag); } } Any ideas on how I can fix this? (I want to avoid using EAGER loading). Do I need to setup some form of session management for transactions? Thanks

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  • Calling Facebook API without authenticating user/"connecting"

    - by Andy
    Hi, I am working with facebook's API and I want to call the links.prevew method. http://wiki.developers.facebook.com/index.php/Links.preview Is it possible to call this method without having my user authenticate or "connect"? For example, not all of my users have hooked up their facebook accounts to my website, but I still want to use this API method. I am getting the following error: Fatal error: Uncaught Exception: 453: A session key is required for calling this method thrown in /public_html/libs/facebook.php on line 413 But on the wiki it says that the method does not require a session key? If it is not possible to make API calls without such a key, is there anyway I can make calls on behalf of my account or my applications account (rather then a users account)? Any help is appreciated, thanks!

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  • Explicitly instantiating a generic member function of a generic structure

    - by Dennis Zickefoose
    I have a structure with a template parameter, Stream. Within that structure, there is a function with its own template parameter, Type. If I try to force a specific instance of the function to be generated and called, it works fine, if I am in a context where the exact type of the structure is known. If not, I get a compile error. This feels like a situation where I'm missing a typename, but there are no nested types. I suspect I'm missing something fundamental, but I've been staring at this code for so long all I see are redheads, and frankly writing code that uses templates has never been my forte. The following is the simplest example I could come up with that illustrates the issue. #include <iostream> template<typename Stream> struct Printer { Stream& str; Printer(Stream& str_) : str(str_) { } template<typename Type> Stream& Exec(const Type& t) { return str << t << std::endl; } }; template<typename Stream, typename Type> void Test1(Stream& str, const Type& t) { Printer<Stream> out = Printer<Stream>(str); /****** vvv This is the line the compiler doesn't like vvv ******/ out.Exec<bool>(t); /****** ^^^ That is the line the compiler doesn't like ^^^ ******/ } template<typename Type> void Test2(const Type& t) { Printer<std::ostream> out = Printer<std::ostream>(std::cout); out.Exec<bool>(t); } template<typename Stream, typename Type> void Test3(Stream& str, const Type& t) { Printer<Stream> out = Printer<Stream>(str); out.Exec(t); } int main() { Test2(5); Test3(std::cout, 5); return 0; } As it is written, gcc-4.4 gives the following: test.cpp: In function 'void Test1(Stream&, const Type&)': test.cpp:22: error: expected primary-expression before 'bool' test.cpp:22: error: expected ';' before 'bool' Test2 and Test3 both compile cleanly, and if I comment out Test1 the program executes, and I get "1 5" as I expect. So it looks like there's nothing wrong with the idea of what I want to do, but I've botched something in the implementation. If anybody could shed some light on what I'm overlooking, it would be greatly appreciated.

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  • Checking who is connected to your server, with PowerShell.

    - by Fatherjack
    There are many occasions when, as a DBA, you want to see who is connected to your SQL Server, along with how they are connecting and what sort of activities they are carrying out. I’m going to look at a couple of ways of getting this information and compare the effort required and the results achieved of each. SQL Server comes with a couple of stored procedures to help with this sort of task – sp_who and its undocumented counterpart sp_who2. There is also the pumped up version of these called sp_whoisactive, written by Adam Machanic which does way more than these procedures. I wholly recommend you try it out if you don’t already know how it works. When it comes to serious interrogation of your SQL Server activity then it is absolutely indispensable. Anyway, back to the point of this blog, we are going to look at getting the information from sp_who2 for a remote server. I wrote this Powershell script a week or so ago and was quietly happy with it for a while. I’m relatively new to Powershell so forgive both my rather low threshold for entertainment and the fact that something so simple is a moderate achievement for me. $Server = 'SERVERNAME' $SMOServer = New-Object Microsoft.SQLServer.Management.SMO.Server $Server # connection and query stuff         $ConnectionStr = "Server=$Server;Database=Master;Integrated Security=True" $Query = "EXEC sp_who2" $Connection = new-object system.Data.SQLClient.SQLConnection $Table = new-object "System.Data.DataTable" $Connection.connectionstring = $ConnectionStr try{ $Connection.open() $Command = $Connection.CreateCommand() $Command.commandtext = $Query $result = $Command.ExecuteReader() $Table.Load($result) } catch{ # Show error $error[0] | format-list -Force } $Title = "Data access processes (" + $Table.Rows.Count + ")" $Table | Out-GridView -Title $Title $Connection.close() So this is pretty straightforward, create an SMO object that represents our chosen server, define a connection to the database and a table object for the results when we get them, execute our query over the connection, load the results into our table object and then, if everything is error free display these results to the PowerShell grid viewer. The query simply gets the results of ‘EXEC sp_who2′ for us. Depending on how many connections there are will influence how long the query runs. The grid viewer lets me sort and search the results so it can be a pretty handy way to locate troublesome connections. Like I say, I was quite pleased with this, it seems a pretty simple script and was working well for me, I have added a few parameters to control the output and give me more specific details but then I see a script that uses the $SMOServer object itself to provide the process information and saves having to define the connection object and query specifications. $Server = 'SERVERNAME' $SMOServer = New-Object Microsoft.SQLServer.Management.SMO.Server $Server $Processes = $SMOServer.EnumProcesses() $Title = "SMO processes (" + $Processes.Rows.Count + ")" $Processes | Out-GridView -Title $Title Create the SMO object of our server and then call the EnumProcesses method to get all the process information from the server. Staggeringly simple! The results are a little different though. Some columns are the same and we can see the same basic information so my first thought was to which runs faster – so that I can get my results more quickly and also so that I place less stress on my server(s). PowerShell comes with a great way of testing this – the Measure-Command function. All you have to do is wrap your piece of code in Measure-Command {[your code here]} and it will spit out the time taken to execute the code. So, I placed both of the above methods of getting SQL Server process connections in two Measure-Command wrappers and pressed F5! The Powershell console goes blank for a while as the code is executed internally when Measure-Command is used but the grid viewer windows appear and the console shows this. You can take the output from Measure-Command and format it for easier reading but in a simple comparison like this we can simply cross refer the TotalMilliseconds values from the two result sets to see how the two methods performed. The query execution method (running EXEC sp_who2 ) is the first set of timings and the SMO EnumProcesses is the second. I have run these on a variety of servers and while the results vary from execution to execution I have never seen the SMO version slower than the other. The difference has varied and the time for both has ranged from sub-second as we see above to almost 5 seconds on other systems. This difference, I would suggest is partly due to the cost overhead of having to construct the data connection and so on where as the SMO EnumProcesses method has the connection to the server already in place and just needs to call back the process information. There is also the difference in the data sets to consider. Let’s take a look at what we get and where the two methods differ Query execution method (sp_who2) SMO EnumProcesses Description - Urn What looks like an XML or JSON representation of the server name and the process ID SPID Spid The process ID Status Status The status of the process Login Login The login name of the user executing the command HostName Host The name of the computer where the  process originated BlkBy BlockingSpid The SPID of a process that is blocking this one DBName Database The database that this process is connected to Command Command The type of command that is executing CPUTime Cpu The CPU activity related to this process DiskIO - The Disk IO activity related to this process LastBatch - The time the last batch was executed from this process. ProgramName Program The application that is facilitating the process connection to the SQL Server. SPID1 - In my experience this is always the same value as SPID. REQUESTID - In my experience this is always 0 - Name In my experience this is always the same value as SPID and so could be seen as analogous to SPID1 from sp_who2 - MemUsage An indication of the memory used by this process but I don’t know what it is measured in (bytes, Kb, Mb…) - IsSystem True or False depending on whether the process is internal to the SQL Server instance or has been created by an external connection requesting data. - ExecutionContextID In my experience this is always 0 so could be analogous to REQUESTID from sp_who2. Please note, these are my own very brief descriptions of these columns, detail can be found from MSDN for columns in the sp_who results here http://msdn.microsoft.com/en-GB/library/ms174313.aspx. Where the columns are common then I would use that description, in other cases then the information returned is purely for interpretation by the reader. Rather annoyingly both result sets have useful information that the other doesn’t. sp_who2 returns Disk IO and LastBatch information which is really useful but the SMO processes method give you IsSystem and MemUsage which have their place in fault diagnosis methods too. So which is better? On reflection I think I prefer to use the sp_who2 method primarily but knowing that the SMO Enumprocesses method is there when I need it is really useful and I’m sure I’ll use it regularly. I’m OK with the fact that it is the slower method because Measure-Command has shown me how close it is to the other option and that it really isn’t a large enough margin to matter.

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  • Multi-Threading in .NET

    - by AIC
    Hi all.. I wrote this program, that is supposed to read about 5000 email address and send an pre-defined html mail. I am using the background worker component. The problem is this: I have wired up the method who is supposed to send the mail. But I am calling another method that is supposed to append the body html to the salutation, like public string GiveMeFullHtml(string personname) ... "Dear Mr. John Doe" + HTML ... It seems that when it hits this method call, operation completes. IUt only sends the first mail and completes. I think because the HTML string method is on another thread or sth like that. Can you give me a little insight. Do I have to get everything done in the very same method when using multi-threading? Thanks in advance

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  • Best way to access database from android

    - by Brandon Delany
    I am working on a Android app and I have a dilemma. I have a list of Objects. I have to update each of these objects with a database. I have 2 methods: Method 1: I can loop through the Objects. For each object I can connect to the server, update it, and then move on to the next Object, and so forth. Method 2: I can store the Objects in a list, send the whole list to the server, update it on the server side, then return a list of updated objects. My questions are: Which method is faster? Which method is easier on the phone's battery? By the way, Method 1 is easier for me to code :). Thank you.

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  • Why does GetClusterShape return null when the cluster specification was retrieved through the GetClu

    - by Markus Olsson
    Suppose I have a virtual earth shape layer called shapeLayer1 (my creative energy is apparently at an alltime low). When i call the GetClusteredShapes method I get an array of VEClusterSpecification objects that represent each and every one of my currently visible clusters; no problem there. But when I call the GetClusterShape() method it returns null... null! Why on earth would it do that? I used firebug to confirm that the private variable of the VEClusterSpecification that's supposed to hold a reference to the shape is indeed null so it's not the method that's causing the problem. Some have suggested that this is actually documented behavior Returns null if a VEClusterSpecification object was returned from the VEShapeLayer.GetClusteredShapes Method But looking at the current MSDN documentation for the VEShape class it says: Returns if a VEClusterSpecification object was returned from the VEShapeLayer.GetClusteredShapes Method Is this a bug or a feature? Is there any known workarounds or (if it is a bug) some plan on when they are going to fix it?

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  • Strange thing about .NET 4.0 filesystem enumeration functionality

    - by codymanix
    I just read a page of "Whats new .NET Framework 4.0". I have trouble understanding the last paragraph: To remove open handles on enumerated directories or files Create a custom method (or function in Visual Basic) to contain your enumeration code. Apply the MethodImplAttribute attribute with the NoInlining option to the new method. For example: [MethodImplAttribute(MethodImplOptions.NoInlining)] Private void Enumerate() Include the following method calls, to run after your enumeration code: * The GC.Collect() method (no parameters). * The GC.WaitForPendingFinalizers() method. Why the attribute NoInlining? What harm would inlining do here? Why call the garbage collector manually, why not making the enumerator implement IDisposable in the first place? I suspect they use FindFirstFile()/FindNextFile() API calls for the imlementation, so FindClose() has to be called in any case if the enumeration is done.

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  • Creating ADF Faces Comamnd Button at Runtime

    - by Frank Nimphius
    Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} In ADF Faces, the command button is an instance of RichCommandButton and can be created at runtime. While creating the button is not difficult at all, adding behavior to it requires knowing about how to dynamically create and add an action listener reference. The example code below shows two methods: The first method, handleButtonPress is a public method exposed on a managed bean. public void handleButtonPress(ActionEvent event){   System.out.println("Event handled");   //optional: partially refresh changed components if command   //issued as a partial submit } The second method is called in response to a user interaction or on page load and dynamically creates and adds a command button. When the button is pressed, the managed bean method – the action handler – defined above is called. The action handler is referenced using EL in the created MethodExpression instance. If the managed bean is in viewScope, backingBeanScope or pageFlowsScope, then you need to add these scopes as a prefix to the EL (as you would when configuring the managed bean reference at design time) //Create command button and add it as a child to the parent component that is passed as an //argument to this method private void reateCommandButton(UIComponent parent){   RichCommandButton edit = new RichCommandButton();   //make the request partial   edit.setPartialSubmit(true);   edit.setText("Edit");                             //compose the method expression to invoke the event handler   FacesContext fctx = FacesContext.getCurrentInstance();   Application application = fctx.getApplication();   ExpressionFactory elFactory = application.getExpressionFactory();   ELContext elContext = facesCtx.getELContext();   MethodExpression methodExpressio = null;   //Make sure the EL expression references a valid managed bean method. Ensure   //the bean scope is properly addressed    methodExpression =  elFactory.createMethodExpression(                              elContext,"#{myRequestScopeBean.handleButtonPress}",                             Object.class,new Class[] {ActionEvent.class});   //Create the command buttonaction listener reference   MethodExpressionActionListener al = null;          al= new MethodExpressionActionListener(methodExpression);    edit.addActionListener(al);     //add new command button to parent component and PPR the component for     //the button to show    parent.getChildren().add(edit);    AdfFacesContext adfFacesContext = AdfFacesContext.getCurrentInstance();     adfFacesContext.addPartialTarget(parent);  }

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  • What's the most efficient way to find barycentric coordinates?

    - by bobobobo
    In my profiler, finding barycentric coordinates is apparently somewhat of a bottleneck. I am looking to make it more efficient. It follows the method in shirley, where you compute the area of the triangles formed by embedding the point P inside the triangle. Code: Vector Triangle::getBarycentricCoordinatesAt( const Vector & P ) const { Vector bary ; // The area of a triangle is real areaABC = DOT( normal, CROSS( (b - a), (c - a) ) ) ; real areaPBC = DOT( normal, CROSS( (b - P), (c - P) ) ) ; real areaPCA = DOT( normal, CROSS( (c - P), (a - P) ) ) ; bary.x = areaPBC / areaABC ; // alpha bary.y = areaPCA / areaABC ; // beta bary.z = 1.0f - bary.x - bary.y ; // gamma return bary ; } This method works, but I'm looking for a more efficient one!

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  • taglib link errors

    - by Vihaan Verma
    I m using taglib for one of my projects . The Debug/Release library is build using MSVC 10. On compiling the code with the library in taglib/taglib/Release some linker error are thrown . id3.cpp.1.o : error LNK2019: unresolved external symbol "__declspec(dllimport) public: class TagLib::AudioPropertie s * __cdecl TagLib::FileRef::audioProperties(void)const " (__imp_?audioProperties@FileRef@TagLib@@QEBAPEAVAudioProp erties@2@XZ) referenced in function "struct MetaData __cdecl ID3::getMetaDataOfFile(class std::basic_string<char,st ruct std::char_traits<char>,class std::allocator<char> >)" (?getMetaDataOfFile@ID3@@YA?AUMetaData@@V?$basic_string@ DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z) id3.cpp.1.o : error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual __cdecl TagLib::Stri ng::~String(void)" (__imp_??1String@TagLib@@UEAA@XZ) referenced in function "struct MetaData __cdecl ID3::getMetaDa taOfFile(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (?getMetaDataOfF ile@ID3@@YA?AUMetaData@@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z) id3.cpp.1.o : error LNK2019: unresolved external symbol "__declspec(dllimport) public: class std::basic_string<char ,struct std::char_traits<char>,class std::allocator<char> > __cdecl TagLib::String::to8Bit(bool)const " (__imp_?to8 Bit@String@TagLib@@QEBA?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@_N@Z) referenced in function "struct MetaData __cdecl ID3::getMetaDataOfFile(class std::basic_string<char,struct std::char_traits<char>,class s td::allocator<char> >)" (?getMetaDataOfFile@ID3@@YA?AUMetaData@@V?$basic_string@DU?$char_traits@D@std@@V?$allocator @D@2@@std@@@Z) id3.cpp.1.o : error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual __cdecl TagLib::File Ref::~FileRef(void)" (__imp_??1FileRef@TagLib@@UEAA@XZ) referenced in function "struct MetaData __cdecl ID3::getMet aDataOfFile(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (?getMetaData OfFile@ID3@@YA?AUMetaData@@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z) id3.cpp.1.o : error LNK2019: unresolved external symbol "__declspec(dllimport) public: class TagLib::Tag * __cdecl TagLib::FileRef::tag(void)const " (__imp_?tag@FileRef@TagLib@@QEBAPEAVTag@2@XZ) referenced in function "struct Meta Data __cdecl ID3::getMetaDataOfFile(class std::basic_string<char,struct std::char_traits<char>,class std::allocator <char> >)" (?getMetaDataOfFile@ID3@@YA?AUMetaData@@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z ) id3.cpp.1.o : error LNK2019: unresolved external symbol "__declspec(dllimport) public: bool __cdecl TagLib::FileRef ::isNull(void)const " (__imp_?isNull@FileRef@TagLib@@QEBA_NXZ) referenced in function "struct MetaData __cdecl ID3: :getMetaDataOfFile(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (?getM etaDataOfFile@ID3@@YA?AUMetaData@@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z) id3.cpp.1.o : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __cdecl TagLib::FileRef::Fil eRef(class TagLib::FileName,bool,enum TagLib::AudioProperties::ReadStyle)" (__imp_??0FileRef@TagLib@@QEAA@VFileName @1@_NW4ReadStyle@AudioProperties@1@@Z) referenced in function "struct MetaData __cdecl ID3::getMetaDataOfFile(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (?getMetaDataOfFile@ID3@@YA?AU MetaData@@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z) id3.cpp.1.o : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __cdecl TagLib::FileName::Fi leName(char const *)" (__imp_??0FileName@TagLib@@QEAA@PEBD@Z) referenced in function "struct MetaData __cdecl ID3:: getMetaDataOfFile(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (?getMe taDataOfFile@ID3@@YA?AUMetaData@@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z) I m only including tag.lib from taglib/taglib/Release folder . Is there some other library I m missing out?

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  • Spring/Hibernate: InvocationTargetException when deleting entity

    - by niklassaers
    I'm sorry if this question is a bit vague, but I'm quite confused. I've got a controller that calls a service to delete an entity and then create an entity in its place. In the service, I've got my DAO, and my entity, and I want to delete my entity, so I call DAO.delete(entity); Then, seemingly out of nowhere, I get an InvocationTargetException. The parameters here are: method: public org.springframework.web.servlet.ModelAndView tld.myproject.view.web.controller.MyController.replaceEntity(org.springframework.web.multipart.MultipartFile,javax.servlet.http.HttpServletRequest) target: tld.myproject.view.web.controller.MyController@185918e args: [org.springframework.web.multipart.commons.CommonsMultipartFile@14812a6, org.springframework.web.multipart.support.DefaultMultipartHttpServletRequest@c08a64] ex: java.lang.reflect.InvocationTargetException private Object doInvokeMethod(Method method, Object target, Object[] args) throws Exception { ReflectionUtils.makeAccessible(method); try { return method.invoke(target, args); } catch (InvocationTargetException ex) { ReflectionUtils.rethrowException(ex.getTargetException()); } throw new IllegalStateException("Should never get here"); } Does anyone have a suggestion to what's going on? Anything I can use in my debugging? Cheers Nik

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  • Should a Unit-test replicate functionality or Test output?

    - by Daniel Beardsley
    I've run into this dilemma several times. Should my unit-tests duplicate the functionality of the method they are testing to verify it's integrity? OR Should unit tests strive to test the method with numerous manually created instances of inputs and expected outputs? I'm mainly asking the question for situations where the method you are testing is reasonably simple and it's proper operation can be verified by glancing at the code for a minute. Simplified example (in ruby): def concat_strings(str1, str2) return str1 + " AND " + str2 end Simplified functionality-replicating test for the above method: def test_concat_strings 10.times do str1 = random_string_generator str2 = random_string_generator assert_equal (str1 + " AND " + str2), concat_strings(str1, str2) end end I understand that most times the method you are testing won't be simple enough to justify doing it this way. But my question remains; is this a valid methodology in some circumstances (why or why not)?

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  • Keypress detection wont work after seemingly unrelated code change

    - by LukeZaz
    I'm trying to have the Enter key cause a new 'map' to generate for my game, but for whatever reason after implementing full-screen in it the input check won't work anymore. I tried removing the new code and only pressing one key at a time, but it still won't work. Here's the check code and the method it uses, along with the newMap method: public class Game1 : Microsoft.Xna.Framework.Game { // ... protected override void Update(GameTime gameTime) { // ... // Check if Enter was pressed - if so, generate a new map if (CheckInput(Keys.Enter, 1)) { blocks = newMap(map, blocks, console); } // ... } // Method: Checks if a key is/was pressed public bool CheckInput(Keys key, int checkType) { // Get current keyboard state KeyboardState newState = Keyboard.GetState(); bool retType = false; // Return type if (checkType == 0) { // Check Type: Is key currently down? if (newState.IsKeyDown(key)) { retType = true; } else { retType = false; } } else if (checkType == 1) { // Check Type: Was the key pressed? if (newState.IsKeyDown(key)) { if (!oldState.IsKeyDown(key)) { // Key was just pressed retType = true; } else { // Key was already pressed, return false retType = false; } } } // Save keyboard state oldState = newState; // Return result if (retType == true) { return true; } else { return false; } } // Method: Generate a new map public List<Block> newMap(Map map, List<Block> blockList, Console console) { // Create new map block coordinates List<Vector2> positions = new List<Vector2>(); positions = map.generateMap(console); // Clear list and reallocate memory previously used up by it blockList.Clear(); blockList.TrimExcess(); // Add new blocks to the list using positions created by generateMap() foreach (Vector2 pos in positions) { blockList.Add(new Block() { Position = pos, Texture = dirtTex }); } // Return modified list return blockList; } // ... } and the generateMap code: // Generate a list of Vector2 positions for blocks public List<Vector2> generateMap(Console console, int method = 0) { ScreenTileWidth = gDevice.Viewport.Width / 16; ScreenTileHeight = gDevice.Viewport.Height / 16; maxHeight = gDevice.Viewport.Height; List<Vector2> blockLocations = new List<Vector2>(); if (useScreenSize == true) { Width = ScreenTileWidth; Height = ScreenTileHeight; } else { maxHeight = Height; } int startHeight = -500; // For debugging purposes, the startHeight is set to an // hopefully-unreachable value - if it returns this, something is wrong // Methods of land generation /// <summary> /// Third version land generation /// Generates a base land height as the second version does /// but also generates a 'max change' value which determines how much /// the land can raise or lower by which it now does by a random amount /// during generation /// </summary> if (method == 0) { // Get the land height startHeight = rnd.Next(1, maxHeight); int maxChange = rnd.Next(1, 5); // Amount ground will raise/lower by int curHeight = startHeight; for (int w = 0; w < Width; w++) { // Run a chance to lower/raise ground level int changeBy = rnd.Next(1, maxChange); int doChange = rnd.Next(0, 3); if (doChange == 1 && !(curHeight <= (1 + maxChange))) { curHeight = curHeight - changeBy; } else if (doChange == 2 && !(curHeight >= (29 - maxChange))) { curHeight = curHeight + changeBy; } for (int h = curHeight; h < Height; h++) { // Location variables float x = w * 16; float y = h * 16; blockLocations.Add(new Vector2(x, y)); } } console.newMsg("[INFO] Cur, height change maximum: " + maxChange.ToString()); } /// <summary> /// Second version land generator /// Generates a solid mass of land starting at a random height /// derived from either screen height or provided height value /// </summary> else if (method == 1) { // Get the land height startHeight = rnd.Next(0, 30); for (int w = 0; w < Width; w++) { for (int h = startHeight; h < ScreenTileHeight; h++) { // Location variables float x = w * 16; float y = h * 16; // Add a tile at set location blockLocations.Add(new Vector2(x, y)); } } } /// <summary> /// First version land generator /// Generates land completely randomly either across screen or /// in a box set by Width and Height values /// </summary> else { // For each tile in the map... for (int w = 0; w < Width; w++) { for (int h = 0; h < Height; h++) { // Location variables float x = w * 16; float y = h * 16; // ...decide whether or not to place a tile... if (rnd.Next(0, 2) == 1) { // ...and if so, add a tile at that location. blockLocations.Add(new Vector2(x, y)); } } } } console.newMsg("[INFO] Cur, base height: " + startHeight.ToString()); return blockLocations; } I never touched any of the above code for this when it broke - changing keys won't seem to fix it. Despite this, I have camera movement set inside another Game1 method that uses WASD and works perfectly. All I did was add a few lines of code here: private int BackBufferWidth = 1280; // Added these variables private int BackBufferHeight = 800; public Game1() { graphics = new GraphicsDeviceManager(this); graphics.PreferredBackBufferWidth = BackBufferWidth; // and this graphics.PreferredBackBufferHeight = BackBufferHeight; // this Content.RootDirectory = "Content"; this.graphics.IsFullScreen = true; // and this } When I try adding a console line to be printed in the event the key is pressed, it seems that the If is never even triggered despite the correct key being pressed.

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  • Mysql 100% CPU + Slow query

    - by felipeclopes
    I'm using the RDS database from amazon with a some very big tables, and yesterday I started to face 100% CPU utilisation on the server and a bunch of slow query logs that were not happening before. I tried to check the queries that were running and faced this result from the explain command +----+-------------+-------------------------------+--------+----------------------------------------------------------------------------------------------+---------------------------------------+---------+-----------------------------------------------------------------+------+----------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------------------------------+--------+----------------------------------------------------------------------------------------------+---------------------------------------+---------+-----------------------------------------------------------------+------+----------------------------------------------+ | 1 | SIMPLE | businesses | const | PRIMARY | PRIMARY | 4 | const | 1 | Using index; Using temporary; Using filesort | | 1 | SIMPLE | activities_businesses | ref | PRIMARY,index_activities_users_on_business_id,index_tweets_users_on_tweet_id_and_business_id | index_activities_users_on_business_id | 9 | const | 2252 | Using index condition; Using where | | 1 | SIMPLE | activities_b_taggings_975e9c4 | ref | taggings_idx | taggings_idx | 782 | const,myapp_production.activities_businesses.id,const | 1 | Using index condition; Using where | | 1 | SIMPLE | activities | eq_ref | PRIMARY,index_activities_on_created_at | PRIMARY | 8 | myapp_production.activities_businesses.activity_id | 1 | Using where | +----+-------------+-------------------------------+--------+----------------------------------------------------------------------------------------------+---------------------------------------+---------+-----------------------------------------------------------------+------+----------------------------------------------+ Also checkin in the process list, I got something like this: +----+-----------------+-------------------------------------+----------------------------+---------+------+--------------+------------------------------------------------------------------------------------------------------+ | Id | User | Host | db | Command | Time | State | Info | +----+-----------------+-------------------------------------+----------------------------+---------+------+--------------+------------------------------------------------------------------------------------------------------+ | 1 | my_app | my_ip:57152 | my_app_production | Sleep | 0 | | NULL | | 2 | my_app | my_ip:57153 | my_app_production | Sleep | 2 | | NULL | | 3 | rdsadmin | localhost:49441 | NULL | Sleep | 9 | | NULL | | 6 | my_app | my_other_ip:47802 | my_app_production | Sleep | 242 | | NULL | | 7 | my_app | my_other_ip:47807 | my_app_production | Query | 231 | Sending data | SELECT my_fields... | | 8 | my_app | my_other_ip:47809 | my_app_production | Query | 231 | Sending data | SELECT my_fields... | | 9 | my_app | my_other_ip:47810 | my_app_production | Query | 231 | Sending data | SELECT my_fields... | | 10 | my_app | my_other_ip:47811 | my_app_production | Query | 231 | Sending data | SELECT my_fields... | | 11 | my_app | my_other_ip:47813 | my_app_production | Query | 231 | Sending data | SELECT my_fields... | ... So based on the numbers, it looks like there is no reason to have a slow query, since the worst execution plan is the one that goes through 2k rows which is not much. Edit 1 Another information that might be useful is the slow query_log SET timestamp=1401457485; SELECT my_query... # User@Host: myapp[myapp] @ ip-10-195-55-233.ec2.internal [IP] Id: 435 # Query_time: 95.830497 Lock_time: 0.000178 Rows_sent: 0 Rows_examined: 1129387 Edit 2 After profiling, I got this result. The result have approximately 250 rows with two columns each. +----------------------+----------+ | state | duration | +----------------------+----------+ | Sending data | 272 | | removing tmp table | 0 | | optimizing | 0 | | Creating sort index | 0 | | init | 0 | | cleaning up | 0 | | executing | 0 | | checking permissions | 0 | | freeing items | 0 | | Creating tmp table | 0 | | query end | 0 | | statistics | 0 | | end | 0 | | System lock | 0 | | Opening tables | 0 | | logging slow query | 0 | | Sorting result | 0 | | starting | 0 | | closing tables | 0 | | preparing | 0 | +----------------------+----------+ Edit 3 Adding query as requested SELECT activities.share_count, activities.created_at FROM `activities_businesses` INNER JOIN `businesses` ON `businesses`.`id` = `activities_businesses`.`business_id` INNER JOIN `activities` ON `activities`.`id` = `activities_businesses`.`activity_id` JOIN taggings activities_b_taggings_975e9c4 ON activities_b_taggings_975e9c4.taggable_id = activities_businesses.id AND activities_b_taggings_975e9c4.taggable_type = 'ActivitiesBusiness' AND activities_b_taggings_975e9c4.tag_id = 104 AND activities_b_taggings_975e9c4.created_at >= '2014-04-30 13:36:44' WHERE ( businesses.id = 1 ) AND ( activities.created_at > '2014-04-30 13:36:44' ) AND ( activities.created_at < '2014-05-30 12:27:03' ) ORDER BY activities.created_at; Edit 4 There may be a chance that the indexes are not being applied due to difference in column type between the taggings and the activities_businesses, on the taggable_id column. mysql> SHOW COLUMNS FROM activities_businesses; +-------------+------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +-------------+------------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | activity_id | bigint(20) | YES | MUL | NULL | | | business_id | bigint(20) | YES | MUL | NULL | | +-------------+------------+------+-----+---------+----------------+ 3 rows in set (0.01 sec) mysql> SHOW COLUMNS FROM taggings; +---------------+--------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +---------------+--------------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | tag_id | int(11) | YES | MUL | NULL | | | taggable_id | bigint(20) | YES | | NULL | | | taggable_type | varchar(255) | YES | | NULL | | | tagger_id | int(11) | YES | | NULL | | | tagger_type | varchar(255) | YES | | NULL | | | context | varchar(128) | YES | | NULL | | | created_at | datetime | YES | | NULL | | +---------------+--------------+------+-----+---------+----------------+ So it is examining way more rows than it shows in the explain query, probably because some indexes are not being applied. Do you guys can help m with that?

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  • Django database caching

    - by hekevintran
    I have a Django form that uses an integer field to lookup a model object by its primary key. The form has a save() method that uses the model object referred to by the integer field. The model's manager's get() method is called twice, once in the clean method and once in the save() method: class MyForm(forms.Form): id_a = fields.IntegerField() def clean_id_a(user_id): id_a = self.cleaned_data['id_a'] try: # here is the first call to get MyModel.objects.get(id=id_a) except User.DoesNotExist: raise ValidationError('Object does not exist') def save(self): id_a = self.cleaned_data['id_a'] # here is the second call to get my_model_object = MyModel.objects.get(id=id_a) # do other stuff I wasn't sure whether this hits the database two times or one time so I returned the object itself in the clean method so that I could avoid a second get() call. Does calling get() hit the database two times? Or is the object cached in the thread? class MyForm(forms.Form): id_a = fields.IntegerField() def clean_id_a(user_id): id_a = self.cleaned_data['id_a'] try: # here is my workaround return MyModel.objects.get(id=id_a) except User.DoesNotExist: raise ValidationError('Object does not exist') def save(self): # looking up the cleaned value returns the model object my_model_object = self.cleaned_data['id_a'] # do other stuff

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  • .Net Reflection - Calling unexisting methods

    - by Joaozinho das Couves
    Lets say i call method M1 on class A using reflection. The method does not exist. Is there any way to put a handler on class A that says, "someone is trying to execute method M1"? Or Is it possible to add a method dinamically to a class? I want to add a method M1...Mn that always does MyStaticClass.DoAction("M1...Mn"); Something like: string methodName = "M1". A.AddMethod(methodname,x = MyStaticClass.DoAction(x)); Thanks

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  • How to setup the c++ rule of three in a virtual base class

    - by Minion91
    I am trying to create a pure virtual base class (or simulated pure virtual) my goal: User can't create instances of BaseClass. Derived classes have to implement default constructor, copy constructor, copy assignment operator and destructor. My attempt: class Base { public: virtual ~Base() {}; /* some pure virtual functions */ private: Base() = default; Base(const Base& base) = default; Base& operator=(const Base& base) = default; } This gives some errors complaining that (for one) the copy constructor is private. But i don't want this mimicked constructor to be called. Can anyone give me the correct construction to do this if this is at all possible?

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  • Lambda&rsquo;s for .NET made easy&hellip;

    - by mbcrump
    The purpose of my blog is to explain things for a beginner to intermediate c# programmer. I’ve seen several blog post that use lambda expressions always assuming the audience is familiar with them. The purpose of this post is to make them simple and easily understood. Let’s begin with a definition. A lambda expression is an anonymous function that can contain expressions and statements, and can be used to create delegates or expression tree types. So anonymous function… delegates or expression tree types? I don’t get it??? Confused yet?   Lets break this into a few definitions and jump right into the code. anonymous function – is an "inline" statement or expression that can be used wherever a delegate type is expected. delegate - is a type that references a method. Once a delegate is assigned a method, it behaves exactly like that method. The delegate method can be used like any other method, with parameters and a return value. Expression trees - represent code in a tree-like data structure, where each node is an expression, for example, a method call or a binary operation such as x < y.   Don’t worry if this still sounds confusing, lets jump right into the code with a simple 3 line program. We are going to use a Function Delegate (all you need to remember is that this delegate returns a value.) Lambda expressions are used most commonly with the Func and Action delegates, so you will see an example of both of these. Lambda Expression 3 lines. using System; using System.Collections.Generic; using System.Linq; using System.Text;   namespace ConsoleApplication7 {     class Program     {          static void Main(string[] args)         {             Func<int, int> myfunc = x => x *x;             Console.WriteLine(myfunc(6).ToString());             Console.ReadLine();         }       } } Is equivalent to Old way of doing it. using System; using System.Collections.Generic; using System.Linq; using System.Text;   namespace ConsoleApplication7 {     class Program     {          static void Main(string[] args)         {               Console.WriteLine(myFunc(6).ToString());             Console.ReadLine();         }            static int myFunc(int x)          {              return x * x;            }       } } In the example, there is a single parameter, x, and the expression is x*x. I’m going to stop here to make sure you are still with me. A lambda expression is an unnamed method written in place of a delegate instance. In other words, the compiler converts the lambda expression to either a : A delegate instance An expression tree All lambda have the following form: (parameters) => expression or statement block Now look back to the ones we have created. It should start to sink in. Don’t get stuck on the => form, use it as an identifier of a lambda. A Lamba expression can also be written in the following form: Lambda Expression. using System; using System.Collections.Generic; using System.Linq; using System.Text;   namespace ConsoleApplication7 {     class Program     {          static void Main(string[] args)         {             Func<int, int> myFunc = x =>             {                 return x * x;             };               Console.WriteLine(myFunc(6).ToString());             Console.ReadLine();         }       } } This form may be easier to read but consumes more space. Lets try an Action delegate – this delegate does not return a value. Action Delegate example. using System; using System.Collections.Generic; using System.Linq; using System.Text;   namespace ConsoleApplication7 {     class Program     {          static void Main(string[] args)         {             Action<string> myAction = (string x) => { Console.WriteLine(x); };             myAction("michael has made this so easy");                                   Console.ReadLine();         }       } } Lambdas can also capture outer variables (such as the example below) A lambda expression can reference the local variables and parameters of the method in which it’s defined. Outer variables referenced by a lambda expression are called captured variables. Capturing Outer Variables using System; using System.Collections.Generic; using System.Linq; using System.Text;   namespace ConsoleApplication7 {     class Program     {          static void Main(string[] args)         {             string mike = "Michael";             Action<string> myAction = (string x) => {                 Console.WriteLine("{0}{1}", mike, x);          };             myAction(" has made this so easy");                                   Console.ReadLine();         }       } } Lamba’s can also with a strongly typed list to loop through a collection.   Used w a strongly typed list. using System; using System.Collections.Generic; using System.Linq; using System.Text;   namespace ConsoleApplication7 {     class Program     {          static void Main(string[] args)         {             List<string> list = new List<string>() { "1", "2", "3", "4" };             list.ForEach(s => Console.WriteLine(s));             Console.ReadLine();         }       } } Outputs: 1 2 3 4 I think this will get you started with Lambda’s, as always consult the MSDN documentation for more information. Still confused? Hopefully you are not.

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  • context.getContextResolved appliaction stopped - begginner in java

    - by Szymad
    I have a problem with my app. I'm trying to execute query, but app stops every time. This error occurs while trying to execute query. I'm learing from Android Pro 3 book, but code presented in this book is deprecated. package com.example.contactsabuout; import android.net.Uri; import android.os.Bundle; import android.provider.Contacts; import android.provider.ContactsContract; import android.app.Activity; import android.database.Cursor; import android.util.Log; import android.content.Context; import android.view.Menu; import android.view.View; import android.widget.TextView; public class MainActivity extends Activity { private static Context context; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); MainActivity.context = getApplicationContext(); Log.v("INFO", "Completed: onCreate."); } public static Context getAppContext() { return MainActivity.context; } public void doQuery(View view) { Uri peopleBaseUri = ContactsContract.Contacts.CONTENT_URI; Log.v("II","Button clicked."); Log.v("II", "Uri for ContactsContract.Contacts: " + peopleBaseUri); Context context = getAppContext(); Log.v("II", "Got context: " + context); Cursor cur; Log.v("II", "Created cursor: cur"); cur = context.getContentResolver().query(peopleBaseUri, null, null, null, null); } @Override public boolean onCreateOptionsMenu(Menu menu) { getMenuInflater().inflate(R.menu.activity_main, menu); return true; } } FROM LogCat 10-28 17:45:02.513: V/INFO(4677): Completed: onCreate. 10-28 17:45:02.613: D/libEGL(4677): loaded /system/lib/egl/libGLES_android.so 10-28 17:45:02.653: D/libEGL(4677): loaded /system/lib/egl/libEGL_adreno200.so 10-28 17:45:02.723: D/libEGL(4677): loaded /system/lib/egl/libGLESv1_CM_adreno200.so 10-28 17:45:02.723: D/libEGL(4677): loaded /system/lib/egl/libGLESv2_adreno200.so 10-28 17:45:03.014: I/Adreno200-EGLSUB(4677): <ConfigWindowMatch:2078>: Format RGBA_8888. 10-28 17:45:03.054: D/OpenGLRenderer(4677): Enabling debug mode 0 10-28 17:45:03.254: D/OpenGLRenderer(4677): has fontRender patch 10-28 17:45:03.274: D/OpenGLRenderer(4677): has fontRender patch 10-28 17:45:12.873: V/II(4677): Button clicked. 10-28 17:45:12.873: V/II(4677): Uri for ContactsContract.Contacts: content://com.android.contacts/contacts, rest will be null 10-28 17:45:12.873: V/II(4677): Got context: android.app.Application@40d83d90 10-28 17:45:12.873: V/II(4677): Created cursor: cur 10-28 17:45:12.933: D/AndroidRuntime(4677): Shutting down VM 10-28 17:45:12.933: W/dalvikvm(4677): threadid=1: thread exiting with uncaught exception (group=0x40aaf228) 10-28 17:45:12.953: E/AndroidRuntime(4677): FATAL EXCEPTION: main 10-28 17:45:12.953: E/AndroidRuntime(4677): java.lang.IllegalStateException: Could not execute method of the activity 10-28 17:45:12.953: E/AndroidRuntime(4677): at android.view.View$1.onClick(View.java:3071) 10-28 17:45:12.953: E/AndroidRuntime(4677): at android.view.View.performClick(View.java:3538) 10-28 17:45:12.953: E/AndroidRuntime(4677): at android.view.View$PerformClick.run(View.java:14330) 10-28 17:45:12.953: E/AndroidRuntime(4677): at android.os.Handler.handleCallback(Handler.java:608) 10-28 17:45:12.953: E/AndroidRuntime(4677): at android.os.Handler.dispatchMessage(Handler.java:92) 10-28 17:45:12.953: E/AndroidRuntime(4677): at android.os.Looper.loop(Looper.java:156) 10-28 17:45:12.953: E/AndroidRuntime(4677): at android.app.ActivityThread.main(ActivityThread.java:4977) 10-28 17:45:12.953: E/AndroidRuntime(4677): at java.lang.reflect.Method.invokeNative(Native Method) 10-28 17:45:12.953: E/AndroidRuntime(4677): at java.lang.reflect.Method.invoke(Method.java:511) 10-28 17:45:12.953: E/AndroidRuntime(4677): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 10-28 17:45:12.953: E/AndroidRuntime(4677): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 10-28 17:45:12.953: E/AndroidRuntime(4677): at dalvik.system.NativeStart.main(Native Method) 10-28 17:45:12.953: E/AndroidRuntime(4677): Caused by: java.lang.reflect.InvocationTargetException 10-28 17:45:12.953: E/AndroidRuntime(4677): at java.lang.reflect.Method.invokeNative(Native Method) 10-28 17:45:12.953: E/AndroidRuntime(4677): at java.lang.reflect.Method.invoke(Method.java:511) 10-28 17:45:12.953: E/AndroidRuntime(4677): at android.view.View$1.onClick(View.java:3066) 10-28 17:45:12.953: E/AndroidRuntime(4677): ... 11 more 10-28 17:45:12.953: E/AndroidRuntime(4677): Caused by: java.lang.SecurityException: Permission Denial: reading com.android.providers.contacts.HtcContactsProvider2 uri content://com.android.contacts/contacts from pid=4677, uid=10155 requires android.permission.READ_CONTACTS 10-28 17:45:12.953: E/AndroidRuntime(4677): at android.os.Parcel.readException(Parcel.java:1332) 10-28 17:45:12.953: E/AndroidRuntime(4677): at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:182) 10-28 17:45:12.953: E/AndroidRuntime(4677): at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:136) 10-28 17:45:12.953: E/AndroidRuntime(4677): at android.content.ContentProviderProxy.query(ContentProviderNative.java:406) 10-28 17:45:12.953: E/AndroidRuntime(4677): at android.content.ContentResolver.query(ContentResolver.java:315) 10-28 17:45:12.953: E/AndroidRuntime(4677): at com.example.contactsabuout.MainActivity.doQuery(MainActivity.java:47) 10-28 17:45:12.953: E/AndroidRuntime(4677): ... 14 more I'm trying to learn android.

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