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  • Declaring an object of a conditional type with a System.Type

    - by Chapso
    I am attempting to launch a specific form depending on the selected node of a treeview on the doubleclick event. The code I need to use to launch the form is a little bulky becuase I have to ensure that the form is not disposed, and that the form is not already open, before launching a new instance. I'd like to have all of this checking happen in one place at the end of the function, which means that I have to be able to pass the right form type to the code at the end. I'm trying to do this with a System.Type, but that doesn't seem to be working. Could someone point me in the right direction, please? With TreeView.SelectedNode Dim formType As Type Select Case .Text Case "Email to VPs" formType = EmailForm.GetType() Case "Revise Replacers" formType = DedicatedReplacerForm.GetType() Case "Start Email" formType = EmailForm.GetType() End Select Dim form As formType Dim form As formType Try form = CType(.Tag, formType) If Not form.IsDisposed Then form.Activate() Exit Sub End If Catch ex As NullReferenceException 'This will error out the first time it is run as the form has not yet ' been defined. End Try form = New formType form.MdiParent = Me .Tag = form CType(TreeView.SelectedNode.Tag, Form).Show() End With

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  • Class lookup structure array in C++

    - by wyatt
    I'm trying to create a structure array which links input strings to classes as follows: struct {string command; CommandPath cPath;} cPathLookup[] = { {"set an alarm", AlarmCommandPath}, {"send an email", EmailCommandPath}, {"", NULL} }; which will be used as follows: CommandPath *cPath = NULL; string input; getline(cin, input); for(int i = 0; cPathLookup[i] != ""; i++) { if(cPathLookup[i].command == input) cPath = new cPathLookup[i].cPath; } Obviously, this code is meaningless, but I think my intention is apparent - depending on input, I'd like cPath to be initialized as either a new AlarmCommandPath or a new EmailCommandPath. I could handle it with a function returning an instance depending on input, but a whole sequence of ifs just seems inelegant. I should also note that, in case it's not apparent and important, that AlarmCommandPath and EmailCommandPath are derived from CommandPath, and CommandPath is an abstract class. Thanks for any help you can offer. EDIT: I just noticed that, in spite of CommandPath being abstract, I have a declaration: CommandPath *cPath = NULL; in working code. Why does that compile?

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  • Session scoped bean as class attribute of Spring MVC Controller

    - by Sotirios Delimanolis
    I have a User class: @Component @Scope("session") public class User { private String username; } And a Controller class: @Controller public class UserManager { @Autowired private User user; @ModelAttribute("user") private User createUser() { return user; } @RequestMapping(value = "/user") public String getUser(HttpServletRequest request) { Random r = new Random(); user.setUsername(new Double(r.nextDouble()).toString()); request.getSession().invalidate(); request.getSession(true); return "user"; } } I invalidate the session so that the next time i got to /users, I get another user. I'm expecting a different user because of user's session scope, but I get the same user. I checked in debug mode and it is the same object id in memory. My bean is declared as so: <bean id="user" class="org.synchronica.domain.User"> <aop:scoped-proxy/> </bean> I'm new to spring, so I'm obviously doing something wrong. I want one instance of User for each session. How?

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  • How to draw mutiple rectangles using c#

    - by Nivas
    I have drawn and saved the Rectangle on the image i loaded in the picture box. How i like to draw multiple rectangles for that i tried array in the rectangle but it gives error ("Object reference not set to an instance of an object." (Null reference Exception was unhandled). enter code here private void pictureBox1_MouseDown(object sender, MouseEventArgs e) { if (mybitmap == null) { mybitmap = new Bitmap(sz.Width, sz.Height); } rect = new Rectangle(e.X, e.Y, 0, 0); this.Invalidate(); } private void pictureBox1_MouseMove(object sender, MouseEventArgs e) { if (stayToolStripMenuItem.Checked == true) { switch (e.Button) { case MouseButtons.Left: { rect = new Rectangle(rect.Left, rect.Top, e.X - rect.Left, e.Y - rect.Top); pictureBox1.Invalidate(); break; } } } } private void pictureBox1_Paint(object sender, PaintEventArgs e) { if (stayToolStripMenuItem.Checked == true) { button1.Visible = true; button2.Visible = true; if (mybitmap == null) { return; } using (g = Graphics.FromImage(mybitmap)) { using (Pen pen = new Pen(Color.Red, 2)) { //g.Clear(Color.Transparent); e.Graphics.DrawRectangle(pen, rect); label1.Top = rect.Top; label1.Left = rect.Left; label1.Width = rect.Width; label1.Height = rect.Height; if (label1.TextAlign == ContentAlignment.TopLeft) { e.Graphics.DrawString(label1.Text, label1.Font, new SolidBrush(label1.ForeColor), rect); g.DrawString(label1.Text, label1.Font, new SolidBrush(label1.ForeColor), rect); g.DrawRectangle(pen, rect); } } } } } How can i do this.....

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  • In Python, how to make data members visible to subclasses if not known when initializing an object ?

    - by LB
    The title is a bit long, but it should be pretty straightforward for someone well-aware of python. I'm a python newbie. So, maybe i'm doing things in the wrong way. Suppose I have a class TreeNode class TreeNode(Node): def __init__(self, name, id): Node.__init__(self, name, id) self.children = [] and a subclass with a weight: class WeightedNode(TreeNode): def __init__(self,name, id): TreeNode.__init__(self, name, id) self.weight = 0 So far, i think I'm ok. Now, I want to add an object variable called father in TreeNode so that WeightedNode has also this member. The problem is that I don't know when initializing the object who is going to be the father. I set the father afterwards with this method in TreeNode : def set_father(self, father_node): self.father = father_node The problem is then when i'm trying to access self.father in Weighted: print 'Name %s Father %s '%(self.name, self.father.name) I obtain: AttributeError: WeightedNode instance has no attribute 'father' I thought that I could make father visible by doing something in TreeNode.__init__ but i wasn't able to find what. How can i do that ? Thanks.

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  • Asynchronously get user data in facebook tab?

    - by Kristoffer Nolgren
    Using the php sdk, I check if a user inside a tab likes the corresponding page. If i put the following code inside index.php and use that page as my page-tab-url, <?php require_once("facebook/facebook.php"); // Create our application instance // (replace this with your appId and secret). $facebook = new Facebook(array( 'appId' => '1399475990283166', 'secret' => 'mysercret', 'cookie' => true )); $signed_request = $facebook->getSignedRequest(); echo $signed_request['page']['liked']; ?> it outputs '1'. I would like to achieve this asynchronously instead, so I put the php in a separate file and try to access it using ajax instead $http.post('/facebook/likes.php'). success(function(data){ console.log(data); }).error(function(data){ console.log(data); } ); This sample is using angular, but what javascript library i'm using probably doesn't matter. When I access the info with javascript Facebook doesn't seem to get the info that I liked the page. Adding a print_r($facebook); on the page I'm retreiving the same values as if i'm not in a facebook-tab: ( [sharedSessionID:protected] => [appId:protected] => 1399475990283166 [appSecret:protected] => 679fb0ab947c2b98e818f9240bc793da [user:protected] => [signedRequest:protected] => [state:protected] => [accessToken:protected] => [fileUploadSupport:protected] => [trustForwarded:protected] => ) Can I access theese values asynchronosly somehow?

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  • rc.local on ubuntu on ec2 will not work

    - by Tampa
    Below are the contents of my rc.local file. When I run sudo /etc/rc.local it works fine. When I boot up and instance. I expect monit to be installed but it is not. I am at a total loss. I usually use rc.local but this is rather confunsing. #!/bin/sh -e # # rc.local # # This script is executed at the end of each multiuser runlevel. # Make sure that the script will "exit 0" on success or any other # value on error. # # In order to enable or disable this script just change the execution # bits. # # By default this script does nothing. apt-get -y install monit /etc/init.d/monit stop cd /home/ubuntu/workspace/rtbopsConfig/ git fetch git checkout origin/master rtb_ec2_boot/ec2_boot.py git checkout origin/master config/ cp /home/ubuntu/workspace/rtbopsConfig/config/monit/redis/monitrc /etc/monit/ /usr/bin/python /home/ubuntu/workspace/rtbopsConfig/rtb_ec2_boot/ec2_boot.py >> /home/ubuntu/workspace/ec2_boot.txt 2>&1 /etc/init.d/monit start chkconfig monit on exit 0

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  • Altering sql tables based on condition

    - by Parker
    Is there any possible way to add a row of data to only some of the tables in a database? I am not sure what parameter I could use amongst the tables to compare them to each other. Any Ideas? For Example: My database has tables that are (let's say) group A tables, and tables that are group B. I want to add a row to only the group B tables while leaving the group A tables untouched. Sorry I should have been a bit more specific. The tables that need to have a row added will change. My application monitors inventory in different store locations(each table in my database represents a store). When I need to add an item to inventory(the items are rows in the tables) I don't want to have to manually add the row to all the store tables. My problem is: Not all the tables in the database represent stores. For instance one table stores the user login data. Obviously I do not want to add the new row to this table. How do I update only the tables that represent stores?

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  • How to re-enable the idle timer in ios once it has been disabled (to allow the display to sleep again)?

    - by lindon fox
    I have figured out how to stop an iOS device from going to sleep (see below), but I am having troubles undoing that setting. According to the Apple Documentation, it should just be changing the value of the idleTimerDisabled property. But when I test this, it does not work. This is how I am initially stopping the device from going to sleep: //need to switch off and on for it to work initially [UIApplication sharedApplication].idleTimerDisabled = NO; [UIApplication sharedApplication].idleTimerDisabled = YES; I would have thought that the following would do the trick: [UIApplication sharedApplication].idleTimerDisabled = NO; From the Apple Documentation: The default value of this property is NO. When most applications have no touches as user input for a short period, the system puts the device into a "sleep” state where the screen dims. This is done for the purposes of conserving power. However, applications that don't have user input except for the accelerometer—games, for instance—can, by setting this property to YES, disable the “idle timer” to avert system sleep. Important: You should set this property only if necessary and should be sure to reset it to NO when the need no longer exists. Most applications should let the system turn off the screen when the idle timer elapses. This includes audio applications. With appropriate use of Audio Session Services, playback and recording proceed uninterrupted when the screen turns off. The only applications that should disable the idle timer are mapping applications, games, or similar programs with sporadic user interaction. Has anyone come across this problem? I am testing on iOS6 and iOS5. Thanks in advance.

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  • Method returns an IDisposable - Should I dispose of the result, even if it's not assigned to anythin

    - by mjd79
    This seems like a fairly straightforward question, but I couldn't find this particular use-case after some searching around. Suppose I have a simple method that, say, determines if a file is opened by some process. I can do this (not 100% correctly, but fairly well) with this: public bool IsOpen(string fileName) { try { File.Open(fileName, FileMode.Open, FileAccess.Read, FileShare.None); } catch { // if an exception is thrown, the file must be opened by some other process return true; } } (obviously this isn't the best or even correct way to determine this - File.Open throws a number of different exceptions, all with different meanings, but it works for this example) Now the File.Open call returns a FileStream, and FileStream implements IDisposable. Normally we'd want to wrap the usage of any FileStream instantiations in a using block to make sure they're disposed of properly. But what happens in the case where we don't actually assign the return value to anything? Is it still necessary to dispose of the FileStream, like so: try { using (File.Open(fileName, FileMode.Open, FileAccess.Read, FileShare.None)); { /* nop */ } } catch { return true; } Should I create a FileStream instance and dispose of that? try { using (FileStream fs = File.Open(fileName, FileMode.Open, FileAccess.Read, FileShare.None)); } ... Or are these totally unnecessary? Can we simply call File.Open and not assign it to anything (first code example), and let the GC dispose of it right away?

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  • Limiting a search to records from last_request_at...

    - by bgadoci
    I am trying to figure out how to display a count for records that have been created in a table since the last_request_at of a user. In my view I am counting the notes of a question with the following code: <% unless @questions.empty? %> <% @questions.each do |question| %> <%= h(question.notes.count) %> end end This is happening in the /views/users/show.html.erb file. Instead of counting all the notes for the question, I would only like to count the notes that have been created since the users last_request_at datetime. I don't neccessarily want to scope notes to display this 'new notes' count application wide, just simply in this one instance. To accomplish I am assuming I need to create a variable in the User#show action and call it in the view but not really sure how to do that. Other information you may need: class Note < ActiveRecord::Base belongs_to :user belongs_to :question end class Question < ActiveRecord::Base has_many :notes, :dependent => :destroy belongs_to :user end

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  • Ordering the results of a Hibernate Criteria query by using information of the child entities of the

    - by pkainulainen
    I have got two entities Person and Book. Only one instance of a specific book is stored to the system (When a book is added, application checks if that book is already found before adding a new row to the database). Relevant source code of the entities is can be found below: @Entity @Table(name="persons") @SequenceGenerator(name="id_sequence", sequenceName="hibernate_sequence") public class Person extends BaseModel { @Id @Column(name = "id") @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "id_sequence") private Long id = null; @ManyToMany(targetEntity=Book.class) @JoinTable(name="persons_books", joinColumns = @JoinColumn( name="person_id"), inverseJoinColumns = @JoinColumn( name="book_id")) private List<Book> ownedBooks = new ArrayList<Book>(); } @Entity @Table(name="books") @SequenceGenerator(name="id_sequence", sequenceName="hibernate_sequence") public class Book extends BaseModel { @Id @Column(name = "id") @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "id_sequence") private Long id = null; @Column(name="name") private String name = null; } My problem is that I want to find persons, which are owning some of the books owned by a specific persons. The returned list of persons should be ordered by using following logic: The person owning most of the same books should be at the first of the list, second person of the the list does not own as many books as the first person, but more than the third person. The code of the method performing this query is added below: @Override public List<Person> searchPersonsWithSimilarBooks(Long[] bookIds) { Criteria similarPersonCriteria = this.getSession().createCriteria(Person.class); similarPersonCriteria.add(Restrictions.in("ownedBooks.id", bookIds)); //How to set the ordering? similarPersonCriteria.addOrder(null); return similarPersonCriteria.list(); } My question is that can this be done by using Hibernate? And if so, how it can be done? I know I could implement a Comparator, but I would prefer using Hibernate to solve this problem.

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  • WCF - Return object without serializing?

    - by Mayo
    One of my WCF functions returns an object that has a member variable of a type from another library that is beyond my control. I cannot decorate that library's classes. In fact, I cannot even use DataContractSurrogate because the library's classes have private member variables that are essential to operation (i.e. if I return the object without those private member variables, the public properties throw exceptions). If I say that interoperability for this particular method is not needed (at least until the owners of this library can revise to make their objects serializable), is it possible for me to use WCF to return this object such that it can at least be consumed by a .NET client? How do I go about doing that? Update: I am adding pseudo code below... // My code, I have control [DataContract] public class MyObject { private TheirObject theirObject; [DataMember] public int SomeNumber { get { return theirObject.SomeNumber; } // public property exposed private set { } } } // Their code, I have no control public class TheirObject { private TheirOtherObject theirOtherObject; public int SomeNumber { get { return theirOtherObject.SomeOtherProperty; } set { // ... } } } I've tried adding DataMember to my instance of their object, making it public, using a DataContractSurrogate, and even manually streaming the object. In all cases, I get some error that eventually leads back to their object not being explicitly serializable.

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  • "Permission denied" with Internet Explorer and jQuery

    - by rallex
    I try to do an AJAX call with jQuery and $.post in Internet Explorer, but all I get is an error saying "Permission denied". The problem is kinda weird since it occurs only when I access a page after I was on any other page. For instance I type the URL in the adress line and let IE load the page. Then I click on a button so the script should start loading JSON data. (The script providing the data lies on the same server and I access it with a relative URL, so using a different domain is not the problem here. Even tried to use a absolute URL with the same host part.) But when I refresh the page then and try it again it works! Same thing when I come to that page from another page. At first nothing works, but when I click "refresh" everything is fine. IE gives me the error message "Permission denied" while in every other browser I don't notice this behaviour. Since I have tried many things and still cannot imagine where the problem lies I'd like to ask you what you think the problem might be?

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  • How can I "reset" styles for a given HTML element?

    - by Sambo
    I am working on an embeddable javascript which inserts HTML elements onto unknown pages. I have no control of the stylesheets of the pages I'll be inserting HTML into. The problem is that the HTML I insert will mistakenly stylized by the page, and I want to prevent that. What's the least verbose and/or resource intensive to go about ensuring the elements I insert are exactly as I'd like them to be? Is there an easy way to clear all styling for a given HTML element and children? In firebug, for instance, you can remove all styling. I feel like there must, and the very least should, be a native way to exempt certain HTML elements from stylesheet rules? Example: var myHTML = $("<div>my html in here</div>"); myHTML.resetAllStyles(); //<--- what would this function do? myHTML.appendTo("body"); I really want to avoid explicitly stating the attributes I want for each element I insert... PS: I have a lot of experience with JS and CSS, so you can assume that I'll understand pretty much anything you're going to tell me.

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  • Is there any better way to capture the screen than PIL.ImageGrab.grab()?

    - by user1474837
    I am making a screen capture program with python. My current problem is PIL.ImageGrab.grab() gives me the same output as 2 seconds later. For instance, for I think I am not being clear, in the following program, almost all the images are the same, have the same Image.tostring() value, even though I was moving my screen during the time the PIL.ImageGrab.grab loop was executing. >>> from PIL.ImageGrab import grab >>> l = [] >>> import time >>> for a in l: l.append(grab()) time.sleep(0.01) >>> for a in range(0, 30): l.append(grab()) time.sleep(0.01) >>> b = [] >>> for a in l: b.append(a.tostring()) >>> len(b) 30 >>> del l >>> last = [] >>> a = 0 >>> a = -1 >>> last = "" >>> same = -1 >>> for pic in b: if b == last: same = same + 1 last = b >>> same 28 >>> This is a problem, as all the images are the same but 1. 1 out of 30 is different. That would make for a absolutly horrable quality video. Please, tell me if there is any better quality alternative to PIL.ImageGrab.grab(). I need to capture the whole screen. Thanks!

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  • linux bash script: set date/time variable to auto-update (for inclusion in file names)

    - by user1859492
    Essentially, I have a standard format for file naming conventions. It breaks down to this: target_dateUTC_timeUTC_tool So, for instance, if I run tcpdump on a target of 'foo', then the file would be foo_dateUTC_timeUTC_tcpdump. Simple enough, but a pain for everyone to constantly (and consistently) enter... so I've tried to create a bash script which sets system variables like so: FILENAME=$TARGET\_$UTCTIME\_$TOOL Then, I can just call the variable at runtime, like so: tcpdump -w $FILENAME.lpc All of this works like a champ. I've got a menu-driven .sh which gives the user the options of viewing the current variables as well as setting them... file generation is a breeze. Unfortunately, by setting the date/time variable, it is locked to the value at the time of creation (naturally). I set the variable like so: UTCTIME=$(/bin/date --utc +"%Y%m%d_%H%M%Z") What I really need is either a way to create a variable which updates at runtime, or (more likely) another way to skin this cat. While scouring for solutions, I came across a similar issues... like this. But, to be honest, I'm stumped on how to marry the two approaches and create a simple, distributable solution. I can post the entire .sh if anyone cares to review (about 120 lines)

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  • Python NameError when attempting to use a user-defined class

    - by Michael Herold
    I'm getting a weird instance of a NameError when attempting to use a class I wrote. In a directory, I have the following file structure: dir/ ReutersParser.py test.py reut-xxx.sgm Where my custom class is defined in ReutersParser.py and I have a test script defined in test.py. The ReutersParser looks something like this: from sgmllib import SGMLParser class ReutersParser(SGMLParser): def __init__(self, verbose=0): SGMLParser.__init__(self, verbose) ... rest of parser if __name__ == '__main__': f = open('reut2-short.sgm') s = f.read() p = ReutersParser() p.parse(s) It's a parser to deal with SGML files of Reuters articles. The test works perfectly. Anyway, I'm going to use it in test.py, which looks like this: from ReutersParser import ReutersParser def main(): parser = ReutersParser() if __name__ == '__main__': main() When it gets to that parser line, I'm getting this error: Traceback (most recent call last): File "D:\Projects\Reuters\test.py", line 34, in <module> main() File "D:\Projects\Reuters\test.py", line 19, in main parser = ReutersParser() File "D:\Projects\Reuters\ReutersParser.py", line 38, in __init__ SGMLParser.__init__(self, verbose) NameError: global name 'sgmllib' is not defined For some reason, when I try to use my ReutersParser in test.py, it throws an error that says it cannot find sgmllib, which is a built-in module. I'm at my wits' end trying to figure out why the import won't work. What's causing this NameError? I've tried importing sgmllib in my test.py and that works, so I don't understand why it can't find it when trying to run the constructor for my ReutersParser.

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  • How to bind Assisted Injected class to interface?

    - by eric2323223
    Here is the problem I met: Class SimpleCommand implements Executable{ private final ConfigManager config; private String name; @Inject public SimpleCommand(ConfigManager config, @Assisted String name){ this.config = config; this.name = name; } } Class MyModule extends AbstractModule{ @Override protected void configure() { bind(CommandFactory.class).toProvider(FactoryProvider.newFactory(CommandFactory.class, SimpleCommand.class)); bind(Executable.class).to(SimpleCommand.class); } } When I try to get instance of SimpleCommand using: Guice.createInjector(new MyModule()).getInstance(CommandFactory.class).create("sample command"); I got this error: 1) No implementation for java.lang.String annotated with @com.google.inject.assistedinject.Assisted(value=) was bound. while locating java.lang.String annotated with @com.google.inject.assistedinject.Assisted(value=) for parameter 2 at model.Command.<init>(SimpleCommand.java:58) at module.MyModule.configure(MyModule.java:34) So my problem is how can I bind SimpleCommand to Executable when SimpleCommand has Assisted Injected parameter? Here is the CommandFactory and its implementation: public interface CommandFactory{ public Command create(String name); } public class GuiceCommandFactory implements CommandFactory{ private Provider<ConfigManager> configManager ; @Inject public GuiceCommandFactory(Provider<ConfigManager> configManager){ this.configManager = configManager; } public Command create(String cmd){ return new Command(configManager.get(), cmd); } }

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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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  • Ways to make (relatively) safe assumptions about the type of concrete subclasses?

    - by Kylotan
    I have an interface (defined as a abstract base class) that looks like this: class AbstractInterface { public: bool IsRelatedTo(const AbstractInterface& other) const = 0; } And I have an implementation of this (constructors etc omitted): class ConcreteThing { public: bool IsRelatedTo(const AbstractInterface& other) const { return m_ImplObject.has_relationship_to(other.m_ImplObject); } private: ImplementationObject m_ImplObject; } The AbstractInterface forms an interface in Project A, and the ConcreteThing lives in Project B as an implementation of that interface. This is so that code in Project A can access data from Project B without having a direct dependency on it - Project B just has to implement the correct interface. Obviously the line in the body of the IsRelatedTo function cannot compile - that instance of ConcreteThing has an m_ImplObject member, but it can't assume that all AbstractInterfaces do, including the other argument. In my system, I can actually assume that all implementations of AbstractInterface are instances of ConcreteThing (or subclasses thereof), but I'd prefer not to be casting the object to the concrete type in order to get at the private member, or encoding that assumption in a way that will crash without a diagnostic later if this assumption ceases to hold true. I cannot modify ImplementationObject, but I can modify AbstractInterface and ConcreteThing. I also cannot use the standard RTTI mechanism for checking a type prior to casting, or use dynamic_cast for a similar purpose. I have a feeling that I might be able to overload IsRelatedTo with a ConcreteThing argument, but I'm not sure how to call it via the base IsRelatedTo(AbstractInterface) method. It wouldn't get called automatically as it's not a strict reimplementation of that method. Is there a pattern for doing what I want here, allowing me to implement the IsRelatedTo function via ImplementationObject::has_relationship_to(ImplementationObject), without risky casts? (Also, I couldn't think of a good question title - please change it if you have a better one.)

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  • Does using functional languages help against computing values repeatedly?

    - by sharptooth
    Consider a function f(x,y): f(x,0) = x*x; f(0,y) = y*(y + 1); f(x,y) = f(x,y-1) + f(x-1,y); If one tries to implement that recursively in some language like C++ he will encounter a problem. Suppose the function is first called with x = x0 and y = y0. Then for any pair (x,y) where 0 <= x < x0 and 0 <= y < y0 the intermediate values will be computed multiple times - recursive calls will form a huge tree in which multiple leaves will in fact contain the same pairs (x,y). For pairs (x,y) where x and y are both close to 0 values will be computed numerous times. For instance, I tested a similar function implemented in C++ - for x=20 and y=20 its computation takes about 4 hours (yes, four Earth hours!). Obviously the implementation can be rewritten in such way that repeated computation doesn't occur - either iteratively or with a cache table. The question is: will functional languages perform any better and avoid repeated computations when implementing a function like above recursively?

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  • PropertyPlaceholderConfigurer works from Maven command line, but not from Eclipse?

    - by HDave
    I have Eclipse configured to use an external maven instance. Nonetheless I have an integration test that runs fine from the command line, but fails from within Eclipse. The error is a class Spring application context bean error: Cannot convert value of type [java.lang.String] to required type The culprit it a bean that sets property values using a PropertyPlaceholderConfigurer. <!-- property settings for non-JNDI database connections --> <bean id="placeholderConfigUuid" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"> <property name="systemPropertiesModeName" value="SYSTEM_PROPERTIES_MODE_OVERRIDE" /> <property name="location" value="classpath:database.properties" /> <property name="placeholderPrefix" value="$DS{" /> </bean> I know which bean is failing because it appears in the stack trace and because when I replace the $DS{hibernate.dialect} with a static value it works. I have two questions: 1) Since M2Eclipse is using the same Maven setup as the command line, why does one work and the other fail? 2) How to fix this? I really like the ability to run a single jUnit test from within Eclipse on demand.

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  • Sys. engineer has decided to dynamically transform all XSLs into DLLs on website build process. DLL

    - by John Sullivan
    Hello, OS: Win XP. Here is my situation. I have a browser based application. It is "wrapped" in a Visual Basic application. Our "Systems Engineer Senior" has decided to spawn DLL files from all of our XSL pages (many of which have duplicate names) upon building a new instance of the website and have the active server pages (ASPX) use the DLL instead. This has created a "known issue" in which ~200 DLL naming conflicts occur and, thus, half of our application is broken. I think a solution to this problem is that, thankfully, we're generating the names of the DLLs and linking them up with our application dynamically. Therefore we can do something kludgy like generate a hash and append it to the end of the DLL file name when we build our website, then always reference the DLL that had some kind of random string / hash appended to its name. Aside from outright renaming the DLLs, is there another way to have multiple DLLs with the same name register for one application? I think the answer is "No, only between different applications using a special technique." Please confirm. Another question I have on my mind is whether this whole idea is a good practice -- converting our XSL pages (which we use in mass -- every time a response from our web app occurs) into DLL functions that call a "function" to do what the XSL page did via an active server page (ASPX), when we were before just sending an XML response to an XSL page via aspx.

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  • is there something equivalent to 'Address of' or offset operator in .net?

    - by Gio
    We have nested stuctures as such, used as an interface for some device drivers. On occasion we have to update individual elements. An 'address of' operator would be helpful, but an 'offset' function or operator is what I'm really looking for, but not sure how to go about it. In other words, how far is structureN.elementX away from the start of the structure in bytes? [StructLayout(LayoutKind.Sequential)] public struct s1 { UInt16 elem1; UInt16 elem2; UInt16 elem3; } [StructLayout(LayoutKind.Sequential)] public struct s2 { UInt16 elem1; UInt16 elem2; UInt16 elem3; } [StructLayout(LayoutKind.Sequential)] public struct driver { public S1 s1; public S2 s2; } For instance we need to send the device driver some data to update driver.s1.elem3, by way of providing an offset address, data block and length. We would update our local copy, then call the device api with the afore mentioned data. Not sure I have to do this with 'unsafe' method calls. Any help?

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