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  • When is a Web Service constructor called? [Java Netbeans 6.7.1 & Tomcat 6.0.18]

    - by Shaitan00
    I am migrating a Java RMI application to Java Web Service (school assignment) and I've encountered an issue... Currently my Java Server creates an instance of the Remote Object, this object has a constructor and takes a parameter (int ID) which tells it which database to load in memory - works like a charm ... Now, migrating this to Web Services is causing my a problem - first I needed to add a default constructor because it wouldn't deploy without it, and then while doing some reading all these discussions about "stateless web services" kept coming up ... For example, if I "start" my webservice with parameter(0) it would load from Databse 0 and all requests from Clients would be done using that data... I want this to only happen when I start the WebService and NOT everytime the client connects... Loading from the DB is expensive and takes time, so I want to do it once so that clients when they connect just deal with the data in memory ... This is how it works with my Java RMI .... but can this also work with Web Services? Any advice would be much appreciated. Thanks,

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  • Complicated API issue with calling assemblies dynamically?

    - by Stefanos Tses
    I have an interesting challenge that I'm wondering if anyone here can give me some direction. I'm writing a .Net windows forms application that runs on a network and uses an SQL Server to save and pull data. I want to offer a mini "plugin" API, where developers can build their own assemblies and implement a specific interface (IDataManipulate). These assemblies then can be used by my application to call the interface functions and do something. I can create assemblies using my API, copy the file to a folder in my local hard drive and configure my application to use Reflection to call a specific function from the implemented interface (IDataManipulate.Execute). The problem: Since the application will be installed in multiple workstations in the network, is impossible to copy the plugin dlls the users will create to each machine. Solutions I tried: Solution 1 Copy the API dll to a network share. Problem: Requires AllowPartiallyTrustedCallersAttribute, which requires .Net singing, which I can't force from my users. Solution 2 (preferred) Serialize the dll object, save it to the database, deserialize it and call IDataManipulate.Execute. Problem: After deserialization, I try cast it to a IDataManipulate object but returns an error looking for the actual dll file. Solution 3 Save the dll bytes as byte[] to the database and recreate the dll at the local PC every time the user starts my application. Problem: Dll may have dependencies, which I don't know if I can detect. Any suggestions will be greatly appreciated. Thanks

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  • Why in the world is this Moq + NUnit test failing?

    - by Dave Falkner
    I have this dataAccess mock object and I'm trying to verify that one of its methods is being invoked, and that the argument passed into this method fulfills certain constraints. As best I can tell, this method is indeed being invoked, and with the constraints fulfilled. This line of the test throws a MockException: data.Verify(d => d.InsertInvoice(It.Is<Invoice>(i => i.TermPaymentAmount == 0m)), Times.Once()); However, removing the constraint and accepting any invoice passes the test: data.Verify(d => d.InsertInvoice(It.IsAny<Invoice>()), Times.Once()); I've created a test windows form that instantiates this test class, runs its .Setup() method, and then calls the method which I am wishing to test. I insert a breakpoint on the line of code where the mock object is failing the test data.InsertInvoice(invoice); to actually hover over the invoice, and I can confirm that its .TermPaymentAmount decimal property is indeed zero at the time the method is invoked. Out of desperation, I even added a call back to my dataAccess mock: data.Setup(d => d.InsertInvoice(It.IsAny<Invoice>())).Callback((Invoice inv) => System.Windows.Forms.MessageBox.Show(inv.TermPaymentAmount.ToString("G17"))); And this gives me a message box showing "0". This is really baffling me, and no one else in my shop has been able to figure this out. Any help would be appreciated. A barely related question, which I should probably ask independently, is whether it is preferable to use Mock.Verify(...) as I have here, or to use Mock.Expect(...).Verifiable followed by Mock.VerifyAll() as I have seen other people doing? If the answer is situational, which situations would warrent the use of one over the other?

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  • Python Webkit browser's inspector is missing a few things

    - by NoBugs
    I'm using a Webkit browser inspector like this. When I run it in Ubuntu 12.10, I'm getting errors when using the inspector. For example: ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "Go to line" not found. ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "Filter" not found. ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "Search Previous" not found. ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "Search Next" not found. ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "a:" not found. ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "%d of %d" not found. (geany:2487): Gdk-CRITICAL **: IA__gdk_error_trap_pop: assertion `gdk_error_traps != NULL' failed ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "Sources Panel" not found. ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "Toggle breakpoint" not found. ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "Painting" not found. I also noticed the breadcrumb/slider bar doesn't show when you have the console in the lower half: I don't remember this in earlier versions, and when I use the GTK3 version (from gi.repository import WebKit etc) it has similar problem, and is even worse, scrollbars don't have arrows at top and bottom. Am I missing a step on initializing the Webkit inspector or English locale for it? I would like to debug this issue, but since the inspector object isn't a webview object, I'm not sure I can add an inspector to the inspector? (like how you can use F12 when inspector is its own window in Chrome/Chromium, which lets you debug that inspector). It should be possible, but maybe not with pyGTK?

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  • Returning JSON or XML for Exceptions in Jersey

    - by Dominic
    My goal is to have an error bean returned on a 404 with a descriptive message when a object is not found, and return the same MIME type that was requested. I have a look up resource, which will return the specified object in XML or JSON based on the URI (I have setup the com.sun.jersey.config.property.resourceConfigClass servlet parameter so I dont need the Accept header. My JAXBContextResolver has the ErrorBean.class in its list of types, and the correct JAXBContext is returned for this class because I can see in the logs). eg: http://foobar.com/rest/locations/1.json @GET @Path("{id}") @Produces({MediaType.APPLICATION_JSON, MediaType.APPLICATION_XML}) public Location getCustomer(@PathParam("id") int cId) { //look up location from datastore .... if (location == null) { throw new NotFoundException("Location" + cId + " is not found"); } } And my NotFoundException looks like this: public class NotFoundException extends WebApplicationException { public NotFoundException(String message) { super(Response.status(Response.Status.NOT_FOUND). entity(new ErrorBean( message, Response.Status.NOT_FOUND.getStatusCode() ) .build()); } } The ErrorBean is as follows: @XmlRootElement(name = "error") public class ErrorBean { private String errorMsg; private int errorCode; //no-arg constructor, property constructor, getter and setters ... } However, I'm always getting a 204 No Content response when I try this. I have hacked around, and if I return a string and specify the mime type this works fine: public NotFoundException(String message) { super(Response.status(Response.Status.NOT_FOUND). entity(message).type("text/plain").build()); } I have also tried returning an ErrorBean as a resource. This works fine: {"errorCode":404,"errorMsg":"Location 1 is not found!"}

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  • Windows Form UserControl design time properties

    - by Raffaeu
    I am struggling with a UserControl. I have a UserControl that represent a Pager and it has a Presenter object property exposed in this way: [Browsable(false)] [DesignSerializationAttribute(DesignSerializationAttribute.Hidden)] public object Presenter { get; set; } The code itself works as I can drag and drop a control into a Windows From without having Visual Studio initializing this property. Now, because in the Load event of this control I call a method of the Presenter that at run-time is null ... I have introduced this additional code: public override void OnLoad(...) { if (this.DesignMode) { base.OnLoad(e); return; } presenter.OnViewReady(); } Now, every time I open a Window that contains this UserControl, Visual Studio modifies the Windows designer code. So, as soon as I open it, VS ask me if I want to save it ... and of course, if I add a control to the Window, it doesn't keep the changes ... As soon as I remove the UserControl Pager the problem disappears ... How should I tackle that in the proper way? I just don't want that the presenter property is initialized at design time as it is injected at runtime ...

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  • Use `require()` with `node --eval`

    - by rentzsch
    When utilizing node.js's newish support for --eval, I get an error (ReferenceError: require is not defined) when I attempt to use require(). Here's an example of the failure: $ node --eval 'require("http");' undefined:1 ^ ReferenceError: require is not defined at eval at <anonymous> (node.js:762:36) at eval (native) at node.js:762:36 $ Here's a working example of using require() typed into the REPL: $ node > require("http"); { STATUS_CODES: { '100': 'Continue' , '101': 'Switching Protocols' , '102': 'Processing' , '200': 'OK' , '201': 'Created' , '202': 'Accepted' , '203': 'Non-Authoritative Information' , '204': 'No Content' , '205': 'Reset Content' , '206': 'Partial Content' , '207': 'Multi-Status' , '300': 'Multiple Choices' , '301': 'Moved Permanently' , '302': 'Moved Temporarily' , '303': 'See Other' , '304': 'Not Modified' , '305': 'Use Proxy' , '307': 'Temporary Redirect' , '400': 'Bad Request' , '401': 'Unauthorized' , '402': 'Payment Required' , '403': 'Forbidden' , '404': 'Not Found' , '405': 'Method Not Allowed' , '406': 'Not Acceptable' , '407': 'Proxy Authentication Required' , '408': 'Request Time-out' , '409': 'Conflict' , '410': 'Gone' , '411': 'Length Required' , '412': 'Precondition Failed' , '413': 'Request Entity Too Large' , '414': 'Request-URI Too Large' , '415': 'Unsupported Media Type' , '416': 'Requested Range Not Satisfiable' , '417': 'Expectation Failed' , '418': 'I\'m a teapot' , '422': 'Unprocessable Entity' , '423': 'Locked' , '424': 'Failed Dependency' , '425': 'Unordered Collection' , '426': 'Upgrade Required' , '500': 'Internal Server Error' , '501': 'Not Implemented' , '502': 'Bad Gateway' , '503': 'Service Unavailable' , '504': 'Gateway Time-out' , '505': 'HTTP Version not supported' , '506': 'Variant Also Negotiates' , '507': 'Insufficient Storage' , '509': 'Bandwidth Limit Exceeded' , '510': 'Not Extended' } , IncomingMessage: { [Function: IncomingMessage] super_: [Function: EventEmitter] } , OutgoingMessage: { [Function: OutgoingMessage] super_: [Function: EventEmitter] } , ServerResponse: { [Function: ServerResponse] super_: [Circular] } , ClientRequest: { [Function: ClientRequest] super_: [Circular] } , Server: { [Function: Server] super_: { [Function: Server] super_: [Function: EventEmitter] } } , createServer: [Function] , Client: { [Function: Client] super_: { [Function: Stream] super_: [Function: EventEmitter] } } , createClient: [Function] , cat: [Function] } > Is there a way to use require() with node's --eval? I'm on node 0.2.6 on Mac OS X 10.6.5.

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  • How to get the value of an XML element using Linq even when empty.

    - by Yeodave
    Please excuse my stupidity, I tend to find the traversing XML overly complicated. I am using ASP.NET in VB. I have an XML document which contains all the details of staff in my company... <staff> <staffName>Test Staff</staffName> <staffTitle>Slave</staffTitle> <staffDepartmentName>Finance</staffDepartmentName> <staffOffice>London</staffOffice> <staffEmail>[email protected]</staffEmail> <staffPhone>0207 123 456</staffPhone> <staffNotes>Working hours Mon to Thurs 9.15 - 5.15</staffNotes> <staffBio></staffBio> </staff> As you can see, some nodes do not always contain data for ever member of staff; only Directors have biographies. I access the values like this... For Each staff In ( _ From matches In myXMLFile.Descendants("staff").Descendants("staffName") _ Where matches.Nodes(0).ToString.ToLower.Contains(LCase(search)) _ Order By matches.Value _ Select matches) staffName = staff.Descendants("staffName").Nodes(0).ToString) staffTitle = staff.Descendants("staffTitle").Nodes(0).ToString) staffOffice = staff.Descendants("staffOffice").Nodes(0).ToString) staffEmail = staff.Descendants("staffEmail").Nodes(0).ToString) staffPhone = staff.Descendants("staffPhone").Nodes(0).ToString) staffNotes = staff.Descendants("staffNotes").Nodes(0).ToString) staffBio = staff.Descendants("staffBio").Nodes(0).ToString) ' Do something with that data... Next Once it gets to staffBio I get an error saying "Object reference not set to an instance of an object." obviously because that node does not exist. My question is how can I assign the value to a variable even when it is empty without having to do a conditional check before each assignment?

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  • i not find how in powershell pass through http autentification then use a webservices (lotus/domino)

    - by user1716616
    We have here a domino/lotus webservices i want use with powershell. probleme is in front of webservices lotus admin ask a http autentification. how i can use this webservice?? here what i tryed first scrap the first page and get cookie. $url = "http://xxxxxxx/names.nsf?Login" $CookieContainer = New-Object System.Net.CookieContainer $postData = "Username=web.services&Password=jesuisunestar" $buffer = [text.encoding]::ascii.getbytes($postData) [net.httpWebRequest] $req = [net.webRequest]::create($url) $req.method = "POST" $req.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8" $req.Headers.Add("Accept-Language: en-US") $req.Headers.Add("Accept-Encoding: gzip,deflate") $req.Headers.Add("Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7") $req.AllowAutoRedirect = $false $req.ContentType = "application/x-www-form-urlencoded" $req.ContentLength = $buffer.length $req.TimeOut = 50000 $req.KeepAlive = $true $req.Headers.Add("Keep-Alive: 300"); $req.CookieContainer = $CookieContainer $reqst = $req.getRequestStream() $reqst.write($buffer, 0, $buffer.length) $reqst.flush() $reqst.close() [net.httpWebResponse] $res = $req.getResponse() $resst = $res.getResponseStream() $sr = new-object IO.StreamReader($resst) $result = $sr.ReadToEnd() this seem work but now no idea how i can use cookie with a webservicesproxy??? ps: i success have this to work with c# + visualstudio (just the class reference is autobuilt and i don't understand half of this but it allow me to use .CookieContenaire on the generated webservice )

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  • How to catch this low level MySQL (?) error in PHP/Magento

    - by andnil
    When I'm executing the following statement in Magento with a really large $sku, the execution terminates without any errors thrown what so ever. There are no errors in either Magento's, Apache's or PHP's error logs. Mage::getModel('catalog/product')-loadByAttribute('sku', $sku); Question: How do I catch the error? I've tried to set custom error handlers, and for testing purposes I've also managed to trigger error situations where each of the error handler functions are invoked. But when running the previously mentioned Magento code with a large $sku, none of the error handling functions are executed. error_reporting( -1 ); set_error_handler( array( 'Error', 'captureNormal' ) ); set_exception_handler( array( 'Error', 'captureException' ) ); register_shutdown_function( array( 'Error', 'captureShutdown' ) ); For completeness, this is the $sku I'm passing to loadByAttribute(). (The sku is invalid, but that is not the issue) 1- 9685 0102046|1- 9685 1212100|1- 9685 1212092|1- 9685 1212096|1- 9685 1102100|1- 9685 1102108|1- 9685 1102112|1- 9685 1102092|1- 9685 0102048|1- 9685 0102054|1- 9685 0102056|1- 9685 0102058|1- 9685 1212104|1- 9685 1212108|1- 9685 0212058|1- 9685 0104050|1- 9685 0212050|1- 9685 0212056|1- 9685 0212044|1- 9685 0212048|1- 9685 0212052|1- 9685 0212054|1- 9685 1102104|1- 9685 1102124 Any insight into this matter is much appreciated! Update: Upon further investigation, this is the exact point in the code where execution terminates. when the foreach is executed I guess Magento goes into MySQL world and starts loading up data from the database. \Mage\Catalog\Model\Abstract.php public function loadByAttribute($attribute, $value, $additionalAttributes = '*') { $collection = $this->getResourceCollection() ->addAttributeToSelect($additionalAttributes) ->addAttributeToFilter($attribute, $value) ->setPage(1,1); foreach ($collection as $object) { // <--------------- HERE return $object; } return false; } Note, I'm ONLY interested in finding out how to properly CATCH these kinds of errors, not "fix" the logic. This is so that I can present a proper error message to the user. The example above with the malformed sku is contrived and I have no desire to make my Magento app work with those erroneous skus.

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  • How to do something when AVQueuePlayer finishes the last playeritem

    - by user1634529
    I've got an AVQueuePlayer which I'm creating from an array of 4 AVPlayerItems, and it all plays fine. I want to do something when the last item in the queue finishes playing, I've looked a load of answers on here and this is the one that looks most promising for what I want: The best way to execute code AFTER a sound has finished playing In my button handler i have this code: static const NSString *ItemStatusContext; [thePlayerItemA addObserver:self forKeyPath:@"status" options:0 context:&ItemStatusContext]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(playerItemDidReachEnd) name:AVPlayerItemDidPlayToEndTimeNotification object:thePlayerItemA]; theQueuePlayer = [AVQueuePlayer playerWithPlayerItem:thePlayerItemA]; [theQueuePlayer play]; and then I have a function to handle playerItemDidReachEnd: - (void)playerItemDidReachEnd:(NSNotification *)notification { // Do stuff here NSLog(@"IT REACHED THE END"); } But when I run this I get an Internal Inconsistency Exception: An -observeValueForKeyPath:ofObject:change:context: message was received but not handled. Key path: status Observed object: <AVPlayerItem: 0x735a130, asset = <AVURLAsset: 0x73559c0, URL = file://localhost/Users/mike/Library/Application%20Support/iPhone%20Simulator/5.0/Applications/A0DBEC13-2DA6-4887-B29D-B43A78E173B8/Phonics%2001.app/yes.mp3>> Change: { kind = 1; } What am I doing wrong?

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  • Python list recursion type error

    - by Jacob J Callahan
    I can't seem to figure out why the following code is giving me a TypeError: 'type' object is not iterable pastebin: http://pastebin.com/VFZYY4v0 def genList(self): #recursively generates a sorted list of child node values numList = [] if self.leftChild != 'none': numList.extend(self.leftChild.genList()) #error numList.extend(list((self.Value,))) if self.rightChild != 'none': numList.extend(self.rightChild.genList()) #error return numList code that adds child nodes (works correctly) def addChild(self, child): #add a child node. working if child.Value < self.Value: if self.leftChild == 'none': self.leftChild = child child.parent = self else: self.leftChild.addChild(child) elif child.Value > self.Value: if self.rightChild == 'none': self.rightChild = child child.parent = self else: self.rightChild.addChild(child) Any help would be appreciated. Full interpreter session: >>> import BinTreeNode as BTN >>> node1 = BTN.BinaryTreeNode(5) >>> node2 = BTN.BinaryTreeNode(2) >>> node3 = BTN.BinaryTreeNode(12) >>> node3 = BTN.BinaryTreeNode(16) >>> node4 = BTN.BinaryTreeNode(4) >>> node5 = BTN.BinaryTreeNode(13) >>> node1.addChild(node2) >>> node1.addChild(node3) >>> node1.addChild(node4) >>> node1.addChild(node5) >>> node4.genList() <class 'list'> >>> node1.genList() Traceback (most recent call last): File "<interactive input>", line 1, in <module> File "C:...\python\BinTreeNode.py", line 47, in genList numList.extend(self.leftChild.genList()) #error File "C:...\python\BinTreeNode.py", line 52, in genList TypeError: 'type' object is not iterable

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  • How do you chain functions dynamically in jQuery?

    - by clarke78
    I want to loop through an object that contains functions which will execute one after another. My most ideal approach would be to have these chain somehow (ie. func2 waits for func1 and func3 waits for func2) but this needs to happen dynamically and the functions will all have different durations. I'm using jQuery so I thought that perhaps "queue()" may help but I haven't worked with it much. A main concern is to not add any scope/callbacks to the functions within the object. I'd rather somehow enclose them within a parent function to execute within the loop in order to create the callback/chaining. Here's an example of what I've got now, but dumbed down. Thanks for any help! var obj = [ {'name':'func1','callback':function(){ alert(1); }}, {'name':'func2','callback':function(){ alert(2); }}, {'name':'func3','callback':function(){ alert(3); }} ]; $.each(obj, function(x, el) { el.callback(); });

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  • How do I use Haml in a view in my new plugin?

    - by Eric
    I'm creating a new plugin for a jruby on rails application that will eventually be turned into a gem. Inside my plugin I have controllers, helpers and views. For my views I'd like to use Haml. The problem is that I can't seem to get it to recognize that they are haml templates. Is it even possible to do this? Is there a way for a plugin to have Haml as a dependency for its view? And by that I mean, I intend for the plugin that I'm creating to have a view created by the plugin, that can be used by the application developer. for example: vendor/ plugins/ my_plugin/ lib/ app/ views/ my_plugin_demo/ index.haml.html controllers/ my_plugin_demo_controller.rb helpers/ In my plugin's init.rb, I tried: require 'my_plugin' require 'haml' #doesn't seem to make a difference :( but that didn't seem to make any difference. Has anybody had any experience with this? I can't seem to find any documentation on how to make this work. Are plugin views restricted to .erb templates?

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  • XML Serialization : Has property of type Class1 : Class1 has another property : How to write the property of Class1 into XML?

    - by Wonderlander
    I want to serialize a class. In this class there's a property, type of Class1, while there are other properties in Class1. public abstract class ComponentBase { [ToSerialize]//An attribute defined my me, indicating whether or not to serialize this property. public ComponentArgs Parameters { get; set; } } public class ComponentArgs { public string WorkingPath { get; set; } public IList<Language> Languages { get; set; } public string ComponentOutputPath { get; set; } } The information serialized must be put into a Dictionary, such as ComponentSettings[str_Name]=str_Value. The method used in reading this value is Reflection. pinfo: Property Info got via Type.GetProperties(); componentSettings.Add(pinfo.Name, pinfo.GetValue((object)this, null).ToString()); The information after serialization is: <Parameters>MS.STBIntl.Pippin.Framework.ComponentArgs</Parameters> instead of the value of ComponentArgs.WorkingPath. The solution I thought of is to append to the following line an if judgement: componentSettings.Add(pinfo.Name, pinfo.GetValue((object)this, null).ToString()); if(pinfo is ComponentArgs) componentSettings.Add(pinfo.Name, pinfo.GetValue( (ComponentArgs)this, null).WorkingPath+"\n"+ LanguageList+"\n"+ //Language list is a concatinated string of all elements in the list. (ComponentArgs)this, null).ComponentOutputPath+"\n"+ ); When deserializing, add a judgement of whether the value contains more than 2 "\n", if so, extract each value from the string. But this way seems clumsy and much more like an workaround. I wonder if there's any more professional way of doing it? My reviewer is very particular and he won't accept such a solution. If you know a way, could you please share it with me? Thanks a lot.

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  • Jquery- Get the value of first td in table

    - by Jerry
    Hello. I am trying to get the value of first td in each tr when a users clicks "click". The result below will output aa ,ee or ii. I was thinking about using clesest('tr')..but it always output "Object object". Not sure what to do on this one. Thanks. My html is <table> <tr> <td>aa</td> <td>bb</td> <td>cc</td> <td>dd</td> <td><a href="#" class="hit">click</a></td> </tr> <tr> <td>ee</td> <td>ff</td> <td>gg</td> <td>hh</td> <td><a href="#" class="hit">click</a></td> </tr> <tr> <td>ii</td> <td>jj</td> <td>kk</td> <td>ll</td> <td><a href="#" class="hit">click</a></td> </tr> </table> Jquery $(".hit").click(function(){ var value=$(this).// not sure what to do here alert(value) ; });

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  • Is method reference caching a good idea in Java 8?

    - by gexicide
    Consider I have code like the following: class Foo { Y func(X x) {...} void doSomethingWithAFunc(Function<X,Y> f){...} void hotFunction(){ doSomethingWithAFunc(this::func); } } Consider that hotFunction is called very often. Would it then be advisable to cache this::func, maybe like this: class Foo { Function<X,Y> f = this::func; ... void hotFunction(){ doSomethingWithAFunc(f); } } As far as my understanding of java method references goes, the Virtual Machine creates an object of an anonymous class when a method reference is used. Thus, caching the reference would create that object only once while the first approach creates it on each function call. Is this correct? Should method references that appear at hot positions in the code be cached or is the VM able to optimize this and make the caching superfluous? Is there a general best practice about this or is this highly VM-implemenation specific whether such caching is of any use?

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  • Casting/dereferencing member variable pointer from void*, is this safe?

    - by Damien
    Hi all, I had a problem while hacking a bigger project so I made a simpel test case. If I'm not omitting something, my test code works fine, but maybe it works accidentally so I wanted to show it to you and ask if there are any pitfalls in this approach. I have an OutObj which has a member variable (pointer) InObj. InObj has a member function. I send the address of this member variable object (InObj) to a callback function as void*. The type of this object never changes so inside the callback I recast to its original type and call the aFunc member function in it. In this exampel it works as expected, but in the project I'm working on it doesn't. So I might be omitting something or maybe there is a pitfall here and this works accidentally. Any comments? Thanks a lot in advance. (The problem I have in my original code is that InObj.data is garbage). #include <stdio.h> class InObj { public: int data; InObj(int argData); void aFunc() { printf("Inside aFunc! data is: %d\n", data); }; }; InObj::InObj(int argData) { data = argData; } class OutObj { public: InObj* objPtr; OutObj(int data); ~OutObj(); }; OutObj::OutObj(int data) { objPtr = new InObj(data); } OutObj::~OutObj() { delete objPtr; } void callback(void* context) { ((InObj*)context)->aFunc(); } int main () { OutObj a(42); callback((void*)a.objPtr); }

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  • Overlaying several CLR reference fields with each other in explicit struct?

    - by thr
    Edit: I'm well aware of that this works very well with value types, my specific question is about using this for reference types. I've been tinkering around with structs in .NET/C#, and I just found out that you can do this: using System; using System.Runtime.InteropServices; namespace ConsoleApplication1 { class Foo { } class Bar { } [StructLayout(LayoutKind.Explicit)] struct Overlaid { [FieldOffset(0)] public object AsObject; [FieldOffset(0)] public Foo AsFoo; [FieldOffset(0)] public Bar AsBar; } class Program { static void Main(string[] args) { var overlaid = new Overlaid(); overlaid.AsObject = new Bar(); Console.WriteLine(overlaid.AsBar); overlaid.AsObject = new Foo(); Console.WriteLine(overlaid.AsFoo); Console.ReadLine(); } } } Basically circumventing having to do dynamic casting during runtime by using a struct that has an explicit field layout and then accessing the object inside as it's correct type. Now my question is: Can this lead to memory leaks somehow, or any other undefined behavior inside the CLR? Or is this a fully supported convention that is usable without any issues? I'm aware that this is one of the darker corners of the CLR, and that this technique is only a viable option in very few specific cases.

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  • C++: Static variable inside a constructor, are there any drawbacks or side effects?

    - by doc
    What I want to do: run some prerequisite code whenever instance of the class is going to be used inside a program. This code will check for requiremts etc. and should be run only once. I found that this can be achieved using another object as static variable inside a constructor. Here's an example for a better picture: class Prerequisites { public: Prerequisites() { std::cout << "checking requirements of C, "; std::cout << "registering C in dictionary, etc." << std::endl; } }; class C { public: C() { static Prerequisites prerequisites; std::cout << "normal initialization of C object" << std::endl; } }; What bothers me is that I haven't seen similar use of static variables so far. Are there any drawbacks or side-effects or am I missing something? Or maybe there is a better solution? Any suggestions are welcome.

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  • What makes my code DDD (domain-driven design) qualified?

    - by oykuo
    Hi All, I'm new to DDD and am thinking about using this design technique in my project. However, what strikes me about DDD is that how basic the idea is. Unlike other design techniques such as MVC and TDD, it doesn't seems to contain any ground breaking ideas. For example, I'm sure some of you will have the same feeling that the idea of root aggregates and repositories are nothing new because when you are was writing MVC web applications you have to have one single master object (i.e. the root aggregate) that contain other minor objects (i.e. value objects and entities) in the model layer in order to send data to a strongly typed view. To me, the only new idea in DDD is probably the "Smart" entities (i.e. you are supposed to have business rules on root aggregates) Separation between value object, root aggregate and entities. Can anyone tell me if I have missed out anything here? If that's all there is to DDD, if I update one of my existing MVC application with the above 2 new ideas, can I claim it's an TDD, MVC and DDD applcation?

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  • Why is function's length information of other shared lib in ELF?

    - by minastaros
    Our project (C++, Linux, gcc, PowerPC) consists of several shared libraries. When releasing a new version of the package, only those libs should change whose source code was actually affected. With "change" I mean absolute binary identity (the checksum over the file is compared. Different checksum - different version according to the policy). (I should mention that the whole project is always built at once, no matter if any code has changed or not per library). Usually this can by achieved by hiding private parts of the included Header files and not changing the public ones. However, there was a case where just a delete was added to the destructor of a class TableManager (in the TableManager.cpp file!) of library libTableManager.so, and yet the binary/checksum of library libB.so (which uses class TableManager ) has changed. TableManager.h: class TableManager { public: TableManager(); ~TableManager(); private: int* myPtr; } TableManager.cpp: TableManager::~TableManager() { doSomeCleanup(); delete myPtr; // this delete has been added } By inspecting libB.so with readelf --all libB.so, looking at the .dynsym section, it turned out that the length of all functions, even the dynamically used ones from other libraries, are stored in libB! It looks like this (length is the 668 in the 3rd column): 527: 00000000 668 FUNC GLOBAL DEFAULT UND _ZN12TableManagerD1Ev So my questions are: Why is the length of a function actually stored in the client lib? Wouldn't a start address be sufficient? Can this be suppressed somehow when compiling/linking of libB.so (kind of "stripping")? We would really like to reduce this degree of dependency...

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  • Rails nested association issue

    - by Ben Langfeld
    Ok, so I'm new to both Ruby and Rails and I'm trying to do what I believe is called a nested association (please correct me if this is the wrong terminology). I currently have a User model and a Domains model and I have many to many associations setup (using has_many :through) between the two, and this works fine. I now want to extend this to allow for a single role per domain per user (eg User1 is a member of Domain1 and has the role "Admin"). I have setup a Roles model with a single field (name:string) and have created three roles. I have also added a role_id column to the join table (memberships). I expected (and this is probably the issue) to be able to just use user1 = User.find(1) user1.domains.first => <some domain object> user1.domains.first.role => <some role object> but this returns a method not defined error. Can anyone tell me what I'm failing to grasp here? My model classes can be seen at http://gist.github.com/388200

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  • What access token should i use?

    - by user548458
    I made a posting scores. It worked normaly sometimes. But, now I cant post any score. If I use user accessToken: string path = meID + "/scores"; var parameters = new Dictionary<string, object> (){ { "score", score.ToString () }, { "access_token", accessToken } }; facebook.post (path, parameters, ( error, obj ) => I get error: {"error":{"message":"(#15) This method must be called with an app access_token.", "type":"OAuthException", "code":15}} If I use an app access token: string path = meID + "/scores"; var parameters = new Dictionary<string, object> () { { "score", score.ToString () }, { "access_token", appAccessToken } }; facebook.post (path, parameters, ( error, obj ) => I get other error: {"error":{"message":"A user access token is required to request this resource.", "type":"OAuthException", "code":102}} Help me please, what am i doing wrong? PS: I worked well recently, but now - dont. Cant explain it...

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  • Thread-Safe lazy instantiating using MEF

    - by Xaqron
    // Member Variable private static readonly object _syncLock = new object(); // Now inside a static method foreach (var lazyObject in plugins) { if ((string)lazyObject.Metadata["key"] = "something") { lock (_syncLock) { // It seems the `IsValueCreated` is not up-to-date if (!lazyObject.IsValueCreated) lazyObject.value.DoSomething(); } return lazyObject.value; } } Here I need synchronized access per loop. There are many threads iterating this loop and based on the key they are looking for, a lazy instance is created and returned. lazyObject should not be created more that one time. Although Lazy class is for doing so and despite of the used lock, under high threading I have more than one instance created (I track this with a Interlocked.Increment on a volatile static int and log it somewhere). The problem is I don't have access to definition of Lazy and MEF defines how the Lazy class create objects. I should notice the CompositionContainer has a thread-safe option in constructor which is already used. My questions: 1) Why the lock doesn't work ? 2) Should I use an array of locks instead of one lock for performance improvement ?

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