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  • Implementing IXmlSerializable on a generated class that has XmlTypeAttribute

    - by Josh
    Basically, the initial problem is I need to make a boolean value serialize as 0 or 1. The solution I found was to implement IXmlSerializable, which I did. Unfortunately the class I'm trying to serialize is generated code off a schema and has an XmlTypeAttribute on it. When I try to (de)serialize the object with the XmlSerializer created in the usual manner ( new XmlSerializer(type)) it throws this exception: System.InvalidOperationException: Only XmlRoot attribute may be specified for the type ______ Please use XmlSchemaProviderAttribute to specify schema type. Two options come to mind immediatly: 1) remove the attribute in the generated code. This change would have to be made every time the code was re-generated. 2) Use an XmlAttributeOverrides object when creating the serializer to remove the attribute. This would require the rest of the code base to "know" that it needs to override that attribute. Also, the exception thrown gives absolutly no clue as to what needs to be done to fix it. Both options kinda stink. Is there a third option?

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  • Android How to get position of selected item from gridview without using onclicklistner, using ontouchlistner instead

    - by zonemikel
    I have a gridview, I need to do stuff on motioneven.action_down and do something for motioneven.action_up ... using onclicklistener is great but does not give me this needed functionality. Is there anyway to easily call the gridview and get its selected item in a ontouchlistener ? I've been having limited success with making my own implementation. Its hard to get the right x,y because if i call the child it gives me the x and y relative to the child so a button would be 0,0 to 48,48 but it does not tell you the actual location on the screen relative to the gridview or the screen itself. this is what i've been doing, its partially working so far. Grid.setOnTouchListener(new OnTouchListener() { public boolean onTouch(View v, MotionEvent event) { if (event.getAction() == MotionEvent.ACTION_DOWN) { int x = (int)event.getX(); int y = (int)event.getY(); int position = 0; int childCount = Grid.getChildCount(); Message msg = new Message(); Rect ButtonRect = new Rect(); Grid.getChildAt(0).getDrawingRect(ButtonRect); int InitialLeft = ButtonRect.left + 10; ButtonRect.offsetTo(InitialLeft, ButtonRect.top); // while(position < childCount){ if(ButtonRect.contains(x,y)){break;} if(ButtonRect.right + ButtonRect.width() > Grid.getWidth()) { ButtonRect.offsetTo(InitialLeft, ButtonRect.bottom);} position++; ButtonRect.offsetTo(ButtonRect.right, ButtonRect.top); } msg.what = position; msg.arg1 = ButtonRect.bottom; msg.arg2 = y; cHandler.sendMessage(msg); }// end if action up if (event.getAction() == MotionEvent.ACTION_UP) { } return false; } });

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  • Vector insert() causes program to crash

    - by wrongusername
    This is the first part of a function I have that's causing my program to crash: vector<Student> sortGPA(vector<Student> student) { vector<Student> sorted; Student test = student[0]; cout << "here\n"; sorted.insert(student.begin(), student[0]); cout << "it failed.\n"; ... It crashes right at the sorted part because I can see "here" on the screen but not "it failed." The following error message comes up: Debug Assertion Failed! (a long path here...) Expression: vector emplace iterator outside range For more information on how your program can cause an assertion failure, see the Visual C++ documentation on asserts. I'm not sure what's causing the problem now, since I have a similar line of code elsewhere student.insert(student.begin() + position(temp, student), temp); that does not crash (where position returns an int and temp is another declaration of a struct Student). What can I do to resolve the problem, and how is the first insert different from the second one?

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  • Django unit testing: South-migrated DB works in MySQL, throws duplicate PK error in PostGreSQL. Am I

    - by unclaimedbaggage
    Hi folks, (Worth starting off with a disclaimer: I'm very new to PostGreSQL) I have a django site which involves a standard app/tests.py testing file. If I migrate the DB to MySQL (through South),, the tests all pass. However in PostGresQL, I'm getting the following error: IntegrityError: duplicate key value violates unique constraint "business_contact_pkey" Note this happens while unit testing only - the actual page runs fine in both MySQL & PostGresql. Really having a heckuva time figuring this one out. Anyone have ideas? Below are the Postgresql "\d business_contact" & offending tests.py method if they help. No changes made to either DB except the (same) South migrations Thanks first_name | character varying(200) | not null mobile_phone | character varying(100) | surname | character varying(200) | not null business_id | integer | not null created | timestamp with time zone | not null deleted | boolean | not null default false updated | timestamp with time zone | not null slug | character varying(150) | not null phone | character varying(100) | email | character varying(75) | id | integer | not null default nextval('business_contact_id_seq'::regclass) Indexes: "business_contact_pkey" PRIMARY KEY, btree (id) "business_contact_slug_key" UNIQUE, btree (slug) "business_contact_business_id" btree (business_id) Foreign-key constraints: "business_id_refs_id_772cc1b7b40f4b36" FOREIGN KEY (business_id) REFERENCES business(id) DEFERRABLE INITIALLY DEFERRED Referenced by: TABLE "business" CONSTRAINT "primary_contact_id_refs_id_dfaf59c4041c850" FOREIGN KEY (primary_contact_id) REFERENCES business_contact(id) DEFERRABLE INITIALLY DEFERRED TEST DEF: def test_add_business_contact(self): """ Add a business contact """ contact_slug = 'test-new-contact-added-new-adf' business_id = 1 business = Business.objects.get(id=business_id) postdata = { 'first_name': 'Test', 'surname': 'User', 'business': '1', 'slug': contact_slug, 'email': '[email protected]', 'phone': '12345678', 'mobile_phone': '9823452', 'business': 1, 'business_id': 1, } #Test to ensure contacts that should not exist are not returned contact_not_exists = Contact.objects.filter(slug=contact_slug) self.assertFalse(contact_not_exists) #Add the contact and ensure it is present in the DB afterwards """ contact_add_url = '%s%s/contact/add/' % (settings.BUSINESS_URL, business.slug) self.client.post(contact_add_url, postdata) added_contact = Contact.objects.filter(slug=contact_slug) print added_contact try: self.assertTrue(added_contact) except: formset = ContactForm(postdata) print formset.errors self.assertFalse(True, "Contact not found in the database - most likely, the post values in the test didn't validate against the form")

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  • How to highlight the new created file in JTree

    - by newbie123
    I want to make it like when I click a button, it will create a new file. Then the jTree will highlight the new file. Below are my code. Currently I create new file, i will show the new file but no highlight the file. class FileTreeModel implements TreeModel { private FileNode root; public FileTreeModel(String directory) { root = new FileNode(directory); } public Object getRoot() { return root; } public Object getChild(Object parent, int index) { FileNode parentNode = (FileNode) parent; return new FileNode(parentNode, parentNode.listFiles()[index].getName()); } public int getChildCount(Object parent) { FileNode parentNode = (FileNode) parent; if (parent == null || !parentNode.isDirectory() || parentNode.listFiles() == null) { return 0; } return parentNode.listFiles().length; } public boolean isLeaf(Object node) { return (getChildCount(node) == 0); } public int getIndexOfChild(Object parent, Object child) { FileNode parentNode = (FileNode) parent; FileNode childNode = (FileNode) child; return Arrays.asList(parentNode.list()).indexOf(childNode.getName()); } public void valueForPathChanged(TreePath path, Object newValue) { } public void addTreeModelListener(TreeModelListener l) { } public void removeTreeModelListener(TreeModelListener l) { } } class FileNode extends java.io.File { public FileNode(String directory) { super(directory); } public FileNode(FileNode parent, String child) { super(parent, child); } @Override public String toString() { return getName(); } } jTree = new JTree(); jTree.setBounds(new Rectangle(164, 66, 180, 421)); jTree.setBackground(SystemColor.inactiveCaptionBorder); jTree.setBorder(BorderFactory.createTitledBorder(null, "", TitledBorder.LEADING, TitledBorder.TOP, new Font("Arial", Font.BOLD, 12), new Color(0, 0, 0))); FileTreeModel model = new FileTreeModel(root); jTree.setRootVisible(false); jTree.setModel(model); expandAll(jTree); public void expandAll(JTree tree) { int row = 0; while (row < tree.getRowCount()) { tree.expandRow(row); row++; } }

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  • Hibernate: Walk millions of rows and don't leak memory

    - by Autocracy
    The below code functions, but Hibernate never lets go of its grip of any object. Calling session.clear() causes exceptions regarding fetching a joined class, and calling session.evict(currentObject) before retrieving the next object also fails to free the memory. Eventually I exhaust my heap space. Checking my heap dumps, StatefulPersistenceContext is the garbage collector's root for all references pointing to my objects. public class CriteriaReportSource implements JRDataSource { private ScrollableResults sr; private Object currentObject; private Criteria c; private static final int scrollSize = 10; private int offset = 1; public CriteriaReportSource(Criteria c) { this.c = c; advanceScroll(); } private void advanceScroll() { // ((Session) Main.em.getDelegate()).clear(); this.sr = c.setFirstResult(offset) .setMaxResults(scrollSize) .scroll(ScrollMode.FORWARD_ONLY); offset += scrollSize; } public boolean next() { if (sr.next()) { currentObject = sr.get(0); if (sr.isLast()) { advanceScroll(); } return true; } return false; } public Object getFieldValue(JRField jrf) throws JRException { Object retVal = null; if(currentObject == null) { return null; } try { retVal = PropertyUtils.getProperty(currentObject, jrf.getName()); } catch (Exception ex) { Logger.getLogger(CriteriaReportSource.class.getName()).log(Level.SEVERE, null, ex); } return retVal; } }

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  • android: consume key press, bypassing framework processing

    - by user360024
    What I want android to do: when user presses a single key, have the view respond, but do so without opening a text area and displaying the character associated with the key that was pressed, and without requiring that the Enter key be pressed, and without requiring that the user press Esc to make the text area go away. For example, when user presses "u" (and doesn't press Enter), that means "undo the last action", so the controller and model immediately undo the last action, then the view does an invalidate() and user sees that their last action has been undone. In other words the "u" key press should be silently processed, such that the only visual result is that user's last action has been undone. I've implemented OnKeyListener and provided an onKey() method: the class: public class MyGameView extends View implements OnKeyListener{ in the constructor: //2010jun06, phj: With onKey(), helps let this View consume key presses // before the framework gets a chance to consume the key press. setOnKeyListener((View.OnKeyListener)this); the onKey() method: public boolean onKey(View v, int keyCode, KeyEvent event) { if (keyCode == KeyEvent.KEYCODE_R) { Log.d("BWA", "In onKey received keycode associated with R."); } return true; // meaning the event (key press) has been consumed, so // the framework should not handle this event. } but when user presses "u" key on the emulator keypad, a textarea is opened at the bottom of the screen, the "u" charater is displayed there, and the onKey() method doesn't execute until user presses the Enter key. Is there a way to make android do what I want? Thanks,

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  • DataGridView update datasource directly after changed Checkbox value

    - by SchlaWiener
    I have a System.Windows.Forms DataGridView that is bound to a List<MyObject>. The class MyObject contains a boolean property that is bound to DataGridViewCheckboxCell within the DataGridView. public class MyObject { public decimal DefaultValue {get; set; } public bool HasCustomValue {get;set; } public decimal CustomValue {get;set; } public decimal CurrentValue { get { return HasCustomValue ? CustomValue : DefaultValue; } } If I change the value of HasCustomValue another (readonly) property CurrentValue changes it's value, too. That is done by implementing the INotifyPropertyChanged event (I left that part in the source example for simplicity) If I changed HasCustomValue from outside the DataGridView, the column bound to CurrentValue gets updated immediately. Howevery, If the users enables/disables the checkbox, HasCustomValue is not changed in the underlying datasource unless he leaves the column by clicking with the mouse or pressing the TAB key. Is there a way to force the grid to update the datasource directly after changing a checkbox value? If I bind a Control Property I have the ability to set the DataSourceUpdateMode to Windows.Forms.DataSourceUpdateMode.OnPropertyChanged but I haven't found anything like that in a DataGridView

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  • Help me clean up this crazy lambda with the out keyword

    - by Sarah Vessels
    My code looks ugly, and I know there's got to be a better way of doing what I'm doing: private delegate string doStuff( PasswordEncrypter encrypter, RSAPublicKey publicKey, string privateKey, out string salt ); private bool tryEncryptPassword( doStuff encryptPassword, out string errorMessage ) { ...get some variables... string encryptedPassword = encryptPassword(encrypter, publicKey, privateKey, out salt); ... } This stuff so far doesn't bother me. It's how I'm calling tryEncryptPassword that looks so ugly, and has duplication because I call it from two methods: public bool method1(out string errorMessage) { string rawPassword = "foo"; return tryEncryptPassword( (PasswordEncrypter encrypter, RSAPublicKey publicKey, string privateKey, out string salt) => encrypter.EncryptPasswordAndDoStuff( // Overload 1 rawPassword, publicKey, privateKey, out salt ), out errorMessage ); } public bool method2(SecureString unencryptedPassword, out string errorMessage) { return tryEncryptPassword( (PasswordEncrypter encrypter, RSAPublicKey publicKey, string privateKey, out string salt) => encrypter.EncryptPasswordAndDoStuff( // Overload 2 unencryptedPassword, publicKey, privateKey, out salt ), out errorMessage ); } Two parts to the ugliness: I have to explicitly list all the parameter types in the lambda expression because of the single out parameter. The two overloads of EncryptPasswordAndDoStuff take all the same parameters except for the first parameter, which can either be a string or a SecureString. So method1 and method2 are pretty much identical, they just call different overloads of EncryptPasswordAndDoStuff. Any suggestions? Edit: if I apply Jeff's suggestions, I do the following call in method1: return tryEncryptPassword( (encrypter, publicKey, privateKey) => { var result = new EncryptionResult(); string salt; result.EncryptedValue = encrypter.EncryptPasswordAndDoStuff( rawPassword, publicKey, privateKey, out salt ); result.Salt = salt; return result; }, out errorMessage ); Much the same call is made in method2, just with a different first value to EncryptPasswordAndDoStuff. This is an improvement, but it still seems like a lot of duplicated code.

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  • Pointers, am I doing them correctly? Objective-c/cocoa

    - by Chris
    I have this in my @interface struct track currentTrack; struct track previousTrack; int anInt; Since these are not objects, I do not have to have them like int* anInt right? And if setting non-object values like ints, boolean, etc, I do not have to release the old value right (assuming non-GC environment)? The struct contains objects: typedef struct track { NSString* theId; NSString* title; } *track; Am I doing that correctly? Lastly, I access the struct like this: [currentTrack.title ...]; currentTrack.theId = @"asdf"; //LINE 1 I'm also manually managing the memory (from a setter) for the struct like this: [currentTrack.title autorelease]; currentTrack.title = [newTitle retain]; If I'm understanding the garbage collection correctly, I should be able to ditch that and just set it like LINE 1 (above)? Also with garbage collection, I don't need a dealloc method right? If I use garbage collection does this mean it only runs on OS 10.5+? And any other thing I should know before I switch to garbage collected code? Sorry there are so many questions. Very new to objective-c and desktop programming. Thanks

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  • Parsing custom time format with SimpleDateFormat

    - by ggrigery
    I'm having trouble parsing a date format that I'm getting back from an API and that I have never seen (I believe is a custom format). An example of a date: /Date(1353447000000+0000)/ When I first encountered this format it didn't take me long to see that it was the time in milliseconds with a time zone offset. I'm having trouble extracting this date using SimpleDateFormat though. Here was my first attempt: String weirdDate = "/Date(1353447000000+0000)/"; SimpleDateFormat sdf = new SimpleDateFormat("'/Date('SSSSSSSSSSSSSZ')/'"); Date d1 = sdf.parse(weirdDate); System.out.println(d1.toString()); System.out.println(d1.getTime()); System.out.println(); Date d2 = new Date(Long.parseLong("1353447000000")); System.out.println(d2.toString()); System.out.println(d2.getTime()); And output: Tue Jan 06 22:51:41 EST 1970 532301760 Tue Nov 20 16:30:00 EST 2012 1353447000000 The date (and number of milliseconds parsed) is not even close and I haven't been able to figure out why. After some troubleshooting, I discovered that the way I'm trying to use SDF is clearly flawed. Example: String weirdDate = "1353447000000"; SimpleDateFormat sdf = new SimpleDateFormat("S"); Date d1 = sdf.parse(weirdDate); System.out.println(d1.toString()); System.out.println(d1.getTime()); And output: Wed Jan 07 03:51:41 EST 1970 550301760 I can't say I've ever tried to use SDF in this way to just parse a time in milliseconds because I would normally use Long.parseLong() and just pass it straight into new Date(long) (and in fact the solution I have in place right now is just a regular expression and parsing a long). I'm looking for a cleaner solution that I can easily extract this time in milliseconds with the timezone and quickly parse out into a date without the messy manual handling. Anyone have any ideas or that can spot the errors in my logic above? Help is much appreciated.

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  • Androids ExpandableListView - where to put the button listener for buttons that are children

    - by CommonKnowledge
    I have been playing around a lot with the ExpandableListView and I cannot figure out where to add the button listeners for the button that will be the children in the view. I did manage to get a button listener working that uses getChildView() below, but it seems to be the same listener for all the buttons. The best case scenario is that I would be able to implement the button listeners in the class that instantiates the ExpandableListAdapter class, and not have to put the listeners in the actual ExpandableListAdapter class. At this point I don't even know if that is possible I have been experimenting with this tutorial/code: HERE getChildView() @Override public View getChildView(int set_new, int child_position, boolean view, View view1, ViewGroup view_group1) { ChildHolder childHolder; if (view1 == null) { view1 = LayoutInflater.from(info_context).inflate(R.layout.list_group_item_lv, null); childHolder = new ChildHolder(); childHolder.section_btn = (Button)view1.findViewById(R.id.item_title); view1.setTag(childHolder); childHolder.section_btn.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { Toast.makeText(info_context, "button pushed", Toast.LENGTH_SHORT).show(); } }); }else { childHolder = (ChildHolder) view1.getTag(); } childHolder.section_btn.setText(children_collection.get(set_new).GroupItemCollection.get(child_position).section); Typeface tf = Typeface.createFromAsset(info_context.getAssets(), "fonts/AGENCYR.TTF"); childHolder.section_btn.setTypeface(tf); return view1; } Any help would be much appreciated. Thank you and I will be standing by.

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  • Help with jQuery Validation plugin and a form that uses 'panels'

    - by alex
    I have a form that works in 'sections' that I will refer to as 'panels'. By default, the form is listed out on the page, one panel after the other. However, with JavaScript, it puts the panels into one panel viewer, and displays them one after the other (with prev/next buttons). Example Form Workflow Panel 1: User Details - Panel 2: User Location - Panel 3: User Info - Panel 4: Confirm Details I am using the jQuery Validation plugin. My problem is, I have set up all the rules for all the inputs in the first 3 panels, and I'd like to be able to only validate a subset of them per panel. Example, when pushing 'next panel' after completing name & email (in the 1st, user details panel), I'd like to do a validation only on that panel first, and then get a boolean response (if the 1st panel validated), and if true, then proceed to the next panel. I've played around with a bit of the config, but unfortunately could not get it to work as I wanted. This is my first project with this plugin so I'm quite new to it! Is there a way to add rules dynamically to the plugin? i.e. not on $('form').validate(options) ? What I'd like to do, is call the validate() on the form, with all the error messages, and then on the 'next panel' code, do a switch case to determine which rules to add, and then call a validate() myself.

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  • StoreFilterField input doesn't react

    - by user1289877
    I'm trying to build grid with build in column filtering (using sencha gxt), here is my code: public Grid<Stock> createGrid() { // Columns definition ColumnConfig<Stock, String> nameCol = new ColumnConfig<Stock, String>(props.name(), 100, "Company"); // Column model definition and creation List<ColumnConfig<Stock, ?>> cl = new ArrayList<ColumnConfig<Stock, ?>>(); cl.add(nameCol); ColumnModel<Stock> cm = new ColumnModel<Stock>(cl); // Data populating ListStore<Stock> store = new ListStore<Stock>(props.key()); store.addAll(TestData.getStocks()); // Grid creation with data final Grid<Stock> grid = new Grid<Stock>(store, cm); grid.getView().setAutoExpandColumn(nameCol); grid.setBorders(false); grid.getView().setStripeRows(true); grid.getView().setColumnLines(true); // Filters definition StoreFilterField<Stock> filter = new StoreFilterField<Stock>() { @Override protected boolean doSelect(Store<Stock> store, Stock parent, Stock item, String filter) { // Window.alert(String.valueOf("a")); String name = item.getName(); name = name.toLowerCase(); if (name.startsWith(filter.toLowerCase())) { return true; } return false; } }; filter.bind(store); cm.addHeaderGroup(0, 0, new HeaderGroupConfig(filter, 1, 1)); filter.focus(); return grid; } My problem is: after I run this code, I cannot write anything to filter input, I'm using test data and classes (Stock.java and StockProperties.java) from this example: http://sencha.com/examples-dev/#ExamplePlace:filtergrid I try to put allert in doSelect method to check if this function was called, but it wasn't. Any idea will be welcome. Thanks.

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  • Object-oriented GUI development in python

    - by ptabatt
    Hey guys, new programmer here. I have an assignment for class and I'm stuck... What I need to do is a create a GUI that gives someone a basic arithmetic problem in one box, asks the person to answer it, evaluates it, and tells you if you're right or wrong... Basically, what I have is this: [code] class Lesson(Frame): def init (self, parent=None): Frame.init(self, parent) self.pack() Lesson.make_widgets(self) def make_widgets(self): Label(self, text="").pack(side=TOP) ent = Entry(self) self.a = randrange(1,10) self.b = randrange(1,10) self.expr = choice(["+","-"]) ent.insert(END, str(self.a) + str(self.expr) + str(self.a)) [/code] I've broken this down into many little steps and basically, what I'm trying to do right now is insert a default random expression into the first entry widget. When I run this code, I just get a blank Label. Why is that? How can I put a something like "7+7" into the box? If you absolutely need background to the problem, it's question #3 on this link. http://reed.cs.depaul.edu/lperkovic/csc242/homeworks/Homework8.html -Thanks for all help in advance.

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  • Distribute budget over for ranked components in SQL

    - by Lee
    Assume I have a budget of $10 (any integer) and I want to distribute it over records which have rank field with varying needs. Example: rank Req. Fulfilled? 1 $3 Y 2 $4 Y 3 $2 Y 4 $3 N Those ranks from 1 to 3 should be fulfilled because they are within budget. whereas, the one ranked 4 should not. I want an SQL query to solve that. Below is my initial script: CREATE TABLE budget ( id VARCHAR (32), budget INTEGER, PRIMARY KEY (id)); CREATE TABLE component ( id VARCHAR (32), rank INTEGER, req INTEGER, satisfied BOOLEAN, PRIMARY KEY (id)); INSERT INTO budget (id,budget) VALUES ('1',10); INSERT INTO component (id,rank,req) VALUES ('1',1,3); INSERT INTO component (id,rank,req) VALUES ('2',2,4); INSERT INTO component (id,rank,req) VALUES ('3',3,2); INSERT INTO component (id,rank,req) VALUES ('4',4,3); Thanks in advance for your help. Lee

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  • How do I implement configurations and settings?

    - by Malvolio
    I'm writing a system that is deployed in several places and each site needs its own configurations and settings. A "configuration" is a named value that is necessary to a particular site (e.g., the database URL, S3 bucket name); every configuration is necessary, there is not usually a default, and it's typically string-valued. A setting is a named value but it just tweaks the behavior of the system; it's often numeric or Boolean, and there's usually some default. So far, I've been using property files or thing like them, but it's a terrible solution. Several times, a developer has added a requirement for a configuration but not added the value to file for the live configuration, so the new release passed all the tests, then failed when released to live. Better, of course, for every file to be compiled — so if there's a missing configuration, or one of the wrong type, it won't get past the compiler — and inject the site-specific class into the build for each site. As a bones, a Scala file can easy model more complex values, especially lists, but also maps and tuples. The downside is, the files are sometimes maintained by people who aren't developers, so it has to be pretty self-explanatory, which was the advantage of property files. (Someone explain XML configurations to me: all the complexity of a compilable file but the run-time risk of a property file.) What I'm looking for is an easy pattern for defining a group required names and allowable values. Any suggestions?

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  • What is an efficient strategy for multiple threads posting jobs and waiting for response from a single thread?

    - by jakewins
    In java, what is an efficient solution to the following problem: I have multiple threads (10-20 or so) generating jobs ("Job Creators"), and a single thread capable of performing them ("The worker"). Once a job creator has posted a job, it should wait for the job to finish, yielding no result other than "it's done", before it keeps going. For sending the jobs to the worker thread, I think a ring buffer or similar standard fan-in setup would perhaps be a good approach? But for a Job Creator to find out that her job has been done, I'm not so sure.. The job creators could sleep, and the worker interrupt them when done.. Or each job creator could have an atomic boolean that it checks, and that the worker sets. I dunno, neither of those feel very nice. I'd like to do it with as few (none, if possible) locks as absolutely possible. So to be clear: What I'm looking for is speed, not necessarily simplicity. Does anyone have any suggestions? Links to reading about concurrency strategies would also be very welcome!

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  • Flexible forms and supporting database structure

    - by sunwukung
    I have been tasked with creating an application that allows administrators to alter the content of the user input form (i.e. add arbitrary fields) - the contents of which get stored in a database. Think Modx/Wordpress/Expression Engine template variables. The approach I've been looking at is implementing concrete tables where the specification is consistent (i.e. user profiles, user content etc) and some generic field data tables (i.e. text, boolean) to store non-specific values. Forms (and model fields) would be generated by first querying the tables and retrieving the relevant columns - although I've yet to think about how I would setup validation. I've taken a look at this problem, and it seems to be indicating an EAV type approach - which, from my brief research - looks like it could be a greater burden than the blessings it's flexibility would bring. I've read a couple of posts here, however, which suggest this is a dangerous route: How to design a generic database whose layout may change over time? Dynamic Database Schema I'd appreciate some advice on this matter if anyone has some to give regards SWK

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  • Practice of checking 'trueness' or 'equality' in conditional statements - does it really make sense?

    - by Senthil
    I remember many years back, when I was in school, one of my computer science teachers taught us that it was better to check for 'trueness' or 'equality' of a condition and not the negative stuff like 'inequality'. Let me elaborate - If a piece of conditional code can be written by checking whether an expression is true or false, we should check the 'trueness'. Example: Finding out whether a number is odd - it can be done in two ways: if ( num % 2 != 0 ) { // Number is odd } or if ( num % 2 == 1 ) { // Number is odd } When I was beginning to code, I knew that num % 2 == 0 implies the number is even, so I just put a ! there to check if it is odd. But he was like 'Don't check NOT conditions. Have the practice of checking the 'trueness' or 'equality' of conditions whenever possible.' And he recommended that I use the second piece of code. I am not for or against either but I just wanted to know - what difference does it make? Please don't reply 'Technically the output will be the same' - we ALL know that. Is it a general programming practice or is it his own programming practice that he is preaching to others?

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  • Disable validation in an object in Ruby on Rails

    - by J. Pablo Fernández
    I have an object which whether validation happens or not should depend on a boolean, or in another way, validation is optional. I haven't found a clean way to do it. What I'm currently doing is this (disclaimer: you cannot unsee, leave this page if you are too sensitive): def valid? if perform_validation super else super # Call valid? so that callbacks get called and things like encrypting passwords and generating salt in before_validation actually happen errors.clear # but then clear the errors true # and claim ourselves to be valid. This is super hacky! end end Any better ways? Before you point to the :if argument of many validations, this is for a user model which is using authlogic so it has a lot of validation rules. You can stop reading here if you belive me. If you don't, authlogic already sets some :ifs like: :if => :email_changed? which I have to turn into :if => Proc.new {|user| user.email_changed? and user.perform_validation} and in some other cases, since I'm also using authlogic-oid (OpenID) I just don't have control over the :if, authlogic-oid sets it in a way I cannot change it (in time) without further monkey patching. So I have to override seemingly unrelated functions, catch exceptions if a method doesn't exist, etc. The previous hacky solution if the best of my two attempts.

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  • Determining polygon intersection and containment

    - by Victor Liu
    I have a set of simple (no holes, no self-intersections) polygons, and I need to check that they don't intersect each other (one can be entirely contained in another; that is okay). I can check this by simply checking the per-vertex inside-ness of one polygon versus other polygons. I also need to determine the containment tree, which is the set of relationships that say which polygon contains any given polygon. Since no polygon can intersect any other, then any contained polygon has a unique container; the "next-bigger" one. In other words, if A contains B contains C, then A is the parent of B, and B is the parent of C, and we don't consider A the parent of C. The question: How do I efficiently determine the containment relationships and check the non-intersection criterion? I ask this as one question because maybe a combined algorithm is more efficient than solving each problem separately. The algorithm should take as input a list of polygons, given by a list of their vertices. It should produce a boolean B indicating if none of the polygons intersect any other polygon, and also if B = true, a list of pairs (P, C) where polygon P is the parent of child C. This is not homework. This is for a hobby project I am working on.

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  • Pre-populate iPhone Safari SQLite DB

    - by Matt Rogish
    I'm working with a PhoneGap app that uses Safari local storage (SQlite DB) via Javascript: http://developer.apple.com/safari/library/documentation/iPhone/Conceptual/SafariJSDatabaseGuide/UsingtheJavascriptDatabase/UsingtheJavascriptDatabase.html On first load, the app creates the database, tables, and populates the data via a series of INSERT statements. If the user closes the app while this processing is happening, then my app database is left in an inconsistent state. What I prefer to do is deploy the SQLite DB as part of my iTunes App packaging so nothing must be populated at app cold start. However, I'm not sure if that is possible -- all of the google hits for this topic that I can find are referring to the core-data provided SQLite which is not what we're using... If it's not possible, could I wrap the entire thing in a transaction and keep re-trying it when the app is restarted? Failing that, I guess I can create a simple table with one boolean column "is_app_db_loaded?" and set it to true after I've processed all my inserts. But that's really gross... Ideas? Thanks!!

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  • Implementing Dispose on a class derived from Stream

    - by AnthonyWJones
    I'm building a class that derives from Stream to wrap a COM IStream. However I've come across an issue where I need to release the COM IStream deteministically. Ok so that's easy just use Marshal.ReleaseComObject in the Dispose method. However I'm not sure its that simple. The Stream base class already has an protected virtual method Dispose(boolean). Here is my first idea:- ~ComStreamWrapper() { if (!_Disposed) { iop.Marshal.FreeCoTaskMem(_Int64Ptr); iop.Marshal.ReleaseComObject(_IStream); } } protected override void Dispose(bool disposing) { base.Dispose(disposing); if (!_Disposed) { if (disposing) { iop.Marshal.FreeCoTaskMem(_Int64Ptr); iop.Marshal.ReleaseComObject(_IStream); } _Disposed = true; } } You'll notice there isn't an implementation of Dispose() itself. I'm currently making the asssumption that the existing implementation on Stream does what I need it to. That is calling Diposing(true) and GC.SuppressFinalize. Is this assumption faulty? Have I missed something? Is there a better approach? You see more of the basic class in this answer to an ealier question.

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  • movieClip in Array displays null, and aren't showing up on stage.addChild(Array[i])

    - by jtdino
    i am new to Actionscript3, i need to know why i keep getting Parameter child must be non-null. And my code won't display 5 enemyBlock objects onto the stage but only just one. any tips and help will be much appreciated. thanks in advance. returns: TypeError: Error #2007: Parameter child must be non-null. at flash.display::DisplayObjectContainer/addChild() at flash.display::Stage/addChild() at BlockDrop_fla::MainTimeline/EnemyBlockPos() at BlockDrop_fla::MainTimeline/frame2() // declare varibles var isEnemyMoving:Boolean = false; var enemyArray:Array; var enemyBlock:MovieClip = new EnemyBlock(); // assign EnemyBlock class to enemyBlock var enemyBlockMC:MovieClip; var count:int = 5; var mapWidth:Number = 800; var mapHeight:Number = 600; function EnemyBlockPos() :void { // assign new MovieClip not null enemyBlockMC = new MovieClip; enemyArray = new Array(); for(var i=1; i<= count; i++){ // add class to MC enemyBlockMC.addChild(enemyBlock); // randomize position enemyBlock.x = Math.round(Math.random()*mapWidth); enemyBlock.y = Math.round(Math.random()*mapHeight); // set motion enemyBlock.movement = 5; // add MC to array enemyArray.push(enemyBlockMC); } for (var w = 1; w <= enemyArray.length; w++) { addChild(enemyArray[w]); } } // endOf EnemyBlockPos

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