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  • Reversible numerical calculations in Prolog

    - by user8472
    While reading SICP I came across logic programming chapter 4.4. Then I started looking into the Prolog programming language and tried to understand some simple assignments in Prolog. I found that Prolog seems to have troubles with numerical calculations. Here is the computation of a factorial in standard Prolog: f(0, 1). f(A, B) :- A > 0, C is A-1, f(C, D), B is A*D. The issues I find is that I need to introduce two auxiliary variables (C and D), a new syntax (is) and that the problem is non-reversible (i.e., f(5,X) works as expected, but f(X,120) does not). Naively, I expect that at the very least C is A-1, f(C, D) above may be replaced by f(A-1,D), but even that does not work. My question is: Why do I need to do this extra "stuff" in numerical calculations but not in other queries? I do understand (and SICP is quite clear about it) that in general information on "what to do" is insufficient to answer the question of "how to do it". So the declarative knowledge in (at least some) math problems is insufficient to actually solve these problems. But that begs the next question: How does this extra "stuff" in Prolog help me to restrict the formulation to just those problems where "what to do" is sufficient to answer "how to do it"?

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  • Using a Context Menu to delete from a SQLite database in Android

    - by LordSnoutimus
    Hi, I have created a list view that displays the names and dates of items stored in a SQLite database, now I want to use a Context Menu to modify these items stored in the database such as edit the name, delete, and view. This is the code for the list view: public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.listview); SQLiteDatabase myDB = null; myDB = this.openOrCreateDatabase(MY_DB_NAME, MODE_PRIVATE, null); Cursor cur = myDB.rawQuery("SELECT _id, trackname, tracktime" + " FROM " + MY_DB_TABLE, null); ListAdapter adapter = new SimpleCursorAdapter(this, R.layout.listview, cur, new String[] { Constants.TRACK_NAME, Constants.TRACK_TIME}, new int[] { R.id.text1, R.id.text2}); ListView list = (ListView)findViewById(R.id.list); list.setAdapter(adapter); registerForContextMenu(list); } and the Context Menu... public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) { super.onCreateContextMenu(menu, v, menuInfo); menu.setHeaderTitle("Track Options"); menu.add(0, CHANGE_NAME, 0, "Change name"); menu.add(0, VIEW_TRACK, 0, "View track"); menu.add(0, SEND_TRACK, 0, "Send track"); menu.add(0, DELETE_TRACK, 0, "Delete track"); } I have used a Switch statement to control the menu items.. public boolean onContextItemSelected(MenuItem item) { switch (item.getItemId()){ case CHANGE_NAME: changename(); return true; case DELETE_TRACK: deletetrack(); return true; default: return super.onContextItemSelected(item); } So how would I go ahead and map the deletetrack(); method to find the ID of the track stored in the database to the item that has been selected in the list view?

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  • How to do HABTM management with auto completion in Rails?

    - by Andrei
    I am looking for a good solution for a probably typical problem of managing models with HABTM association in Rails. Let's assume that we have two models -- products and categories: Products has_many :categorizations has_many :categories, :through => :categorizations Categories has_many :categorizations has_many :products, :through => :categorizations Categorization belongs_to :product belongs_to :category Pat Shaughnessy is developing modified auto_complete plugin which can allow to manage one-to-many (and many-to-many) association: For someone that would be enough, but I don't really like so many text fields. I guess it is possible to combine the Ryan Bates' screencasts used by Pat in a slightly different way, namely, using one text field with autocomplete: Also it would be better to remove from the list of suggested tasks (one-to-many), or products|categories (many-to-many) those which have been already added. In the case of products-categories relationship, such auto completion would be used both in the form for product, and in the form for category. I hope that there is an existing plugin for that. I am not very experienced in Ruby, and don't really know how to implement such logic by myself. Any help is appreciated!

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  • WPF validation on Enter Key Up

    - by Martin
    I'm trying to validate a UI change when Enter key is pressed. The UI element is a textbox, which is data binded to a string. My problem is that the data binding hasn't updated TestText when Enter key is Up. It is only updated when I press the button which brings up a message box. /// <summary> /// Interaction logic for Window1.xaml /// </summary> public partial class Window1 : Window, INotifyPropertyChanged { String _testText = new StringBuilder("One").ToString(); public string TestText { get { return _testText; } set { if (value != _testText) { _testText = value; OnPropertyChanged("TestText"); } } } public Window1() { InitializeComponent(); myGrid.DataContext = this; } private void OnPropertyChanged(string property) { if (PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs(property)); } } public event PropertyChangedEventHandler PropertyChanged; private void onKeyUp(object sender, KeyEventArgs e) { if (e.Key != System.Windows.Input.Key.Enter) return; System.Diagnostics.Trace.WriteLine(TestText); } private void button1_Click(object sender, RoutedEventArgs e) { MessageBox.Show(TestText); } } Window XAML: Window x:Class="VerificationTest.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="Window1" Height="300" Width="300" KeyUp="onKeyUp" TextBox XAML: TextBox Name="myTextBox" Text="{Binding TestText}" Button XAML: Button Name="button1" Click="button1_Click"

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  • Deal with undefined values in code or in the template?

    - by David
    I'm writing a web application (in Python, not that it matters). One of the features is that people can leave comments on things. I have a class for comments, basically like so: class Comment: user = ... # other stuff where user is an instance of another class, class User: name = ... # other stuff And of course in my template, I have <div>${comment.user.name}</div> Problem: Let's say I allow people to post comments anonymously. In that case comment.user is None (undefined), and of course accessing comment.user.name is going to raise an error. What's the best way to deal with that? I see three possibilities: Use a conditional in the template to test for that case and display something different. This is the most versatile solution, since I can change the way anonymous comments are displayed to, say, "Posted anonymously" (instead of "Posted by ..."), but I've often been told that templates should be mindless display machines and not include logic like that. Also, other people might wind up writing alternate templates for the same application, and I feel like I should be making things as easy as possible for the template writer. Implement an accessor method for the user property of a Comment that returns a dummy user object when the real user is undefined. This dummy object would have user.name = 'Anonymous' or something like that and so the template could access it and print its name with no error. Put an actual record in my database corresponding to a user with user.name = Anonymous (or something like that), and just assign that user to any comment posted when nobody's logged in. I know I've seen some real-world systems that operate this way. (phpBB?) Is there a prevailing wisdom among people who write these sorts of systems about which of these (or some other solution) is the best? Any pitfalls I should watch out for if I go one way vs. another? Whoever gives the best explanation gets the checkmark.

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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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  • Numerical calculations in Prolog

    - by user8472
    While reading SICP I came across logic programming chapter 4.4. Then I started looking into the Prolog programming language and tried to understand some simple assignments in Prolog. I found that Prolog seems to have troubles with numerical calculations. Here is the computation of a factorial in standard Prolog: f(0, 1). f(A, B) :- A > 0, C is A-1, f(C, D), B is A*D. The issues I find is that I need to introduce two auxiliary variables (C and D), a new syntax (is) and that the problem is non-reversible (i.e., f(5,X) works as expected, but f(X,120) does not). Naively, I expect that at the very least C is A-1, f(C, D) above may be replaced by f(A-1,D), but even that does not work. My question is: Why do I need to do this extra "stuff" in numerical calculations but not in other queries? I do understand (and SICP is quite clear about it) that in general information on "what to do" is insufficient to answer the question of "how to do it". So the declarative knowledge in (at least some) math problems is insufficient to actually solve these problems. But that begs the next question: How does this extra "stuff" in Prolog help me to restrict the formulation to just those problems where "what to do" is sufficient to answer "how to do it"?

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  • Validate a XDocument against schema without the ValidationEventHandler (for use in a HTTP handler)

    - by Vaibhav Garg
    Hi everyone, (I am new to Schema validation) Regarding the following method, System.Xml.Schema.Extensions.Validate( ByVal source As System.Xml.Linq.XDocument, ByVal schemas As System.Xml.Schema.XmlSchemaSet, ByVal validationEventHandler As System.Xml.Schema.ValidationEventHandler, ByVal addSchemaInfo As Boolean) I am using it as follows inside a IHttpHandler - Try Dim xsd As XmlReader = XmlReader.Create(context.Server.MapPath("~/App_Data/MySchema.xsd")) Dim schemas As New XmlSchemaSet() : schemas.Add("myNameSpace", xsd) : xsd.Close() myXDoxumentOdj.Validate(schemas, Function(s As Object, e As ValidationEventArgs) SchemaError(s, e, context), True) Catch ex1 As Threading.ThreadAbortException 'manage schema error' Return Catch ex As Exception 'manage other errors' End Try The handler- Function SchemaError(ByVal s As Object, ByVal e As ValidationEventArgs, ByVal c As HttpContext) As Object If c Is Nothing Then c = HttpContext.Current If c IsNot Nothing Then HttpContext.Current.Response.Write(e.Message) HttpContext.Current.Response.End() End If Return New Object() End Function This is working fine for me at present but looks very weak. I do get errors when I feed it bad XML. But i want to implement it in a more elegant way. This looks like it would break for large XML etc. Is there some way to validate without the handler so that I get the document validated in one go and then deal with errors? To me it looks Async such that the call to Validate() would pass and some non deterministic time later the handler would get called with the result/errors. Is that right? Thanks and sorry for any goofy mistakes :).

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  • Finding Palindromes in an Array

    - by Jack L.
    For this assignemnt, I think that I got it right, but when I submit it online, it doesn't list it as correct even though I checked with Eclipse. The prompt: Write a method isPalindrome that accepts an array of Strings as its argument and returns true if that array is a palindrome (if it reads the same forwards as backwards) and /false if not. For example, the array {"alpha", "beta", "gamma", "delta", "gamma", "beta", "alpha"} is a palindrome, so passing that array to your method would return true. Arrays with zero or one element are considered to be palindromes. My code: public static void main(String[] args) { String[] input = new String[6]; //{"aay", "bee", "cee", "cee", "bee", "aay"} Should return true input[0] = "aay"; input[1] = "bee"; input[2] = "cee"; input[3] = "cee"; input[4] = "bee"; input[5] = "aay"; System.out.println(isPalindrome(input)); } public static boolean isPalindrome(String[] input) { for (int i=0; i<input.length; i++) { // Checks each element if (input[i] != input[input.length-1-i]){ return false; // If a single instance of non-symmetry } } return true; // If symmetrical, only one element, or zero elements } As an example, {"aay", "bee", "cee", "cee", "bee", "aay"} returns true in Eclipse, but Practice-It! says it returns false. What is going on?

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  • How to calculate commision based on referred memebrs?

    - by RAJKISHOR SAHU
    Hello everybody, I am developing a small software in C# WPF for a consultancy which does chain system business. I have coded tree structure to show who referred whom. Now it has commission depending on level. If 1 referred 2 & 3 then 1 will get level-1 commission. If 2 referred 4, 5 & 3 referred 6, 7 then 1 will receive level-2 commission. This chain will go on to certain total number. My problem is how I would implement this logic; I am able to calculate who has referred how many members via UDF written for adding TreeViewItem to TreeView. Or tell me how I can count items in treeview in certain level? Node adding UDF: public void AddNodes(int uid, TreeViewItem tSubNode) { string query = "select fullname, id from members where refCode=" + uid + ";"; MySqlCommand cmd = new MySqlCommand(query, db.conn); MySqlDataAdapter _DA = new MySqlDataAdapter(cmd); DataTable _DT = new DataTable(); tSubNode.IsExpanded = true; _DA.Fill(_DT); foreach (DataRow _dr in _DT.Rows) { TreeViewItem tNode = new TreeViewItem(); tNode.Header = _dr["fullname"].ToString()+" ("+_dr["id"].ToString()+")"; tSubNode.Items.Add(tNode); if (db.HasMembers(Convert.ToInt32(_dr["id"].ToString()))) { AddNodes(Convert.ToInt32(_dr["id"]), tNode); } } //This line tracks who has referred how many members Console.WriteLine("Tree node Count : "+tSubNode.Items.Count.ToString()+", UID "+uid); } Help me PLEASE!!!!

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  • C++ iterators, default initialization and what to use as an uninitialized sentinel.

    - by Hassan Syed
    The Context I have a custom template container class put together from a map and vector. The map resolves a string to an ordinal, and the vector resolves an ordinal (only an initial string to ordinal lookup is done, future references are to the vector) to the entry. The entries are modified intrusively to contain a a bool "assigned" and an iterator_type which is a const_iterator to the container class's map. My container class will use RCF's serialization code (which models boost::serialization) to serialize my container classes to nodes in a network. Serializing iterator's is not possible, or a can of worms, and I can easily regenerate them onces the vectors and maps are serialized on the remote site. The Question I need to default initialize, and be able to test that the iterator has not been assigned to (if it is assigned it is valid, if not it is invalid). Since map iterators are not invalidated upon operations performed on it (unless of course items are removed :D) am I to assume that map<x,y>::end() is a valid sentinel (regardless of the state of the map -- i.e., it could be empty) to initialize to ? I will always have access to the parent map, I'm just unsure wheather end() is the same as the map contents change. I don't want to use another level of indirection (--i.e., boost::optional) to achieve my goal, I'd rather forego compiler checks to correct logic, but it would be nice if I didn't need to. Misc This question exists, but most of its content seems non-sense. Assigning a NULL to an iterator is invalid according to g++ and clang++. This is another similar question, but it focuses on the common use-cases of iterators, which generally tends to be using the iterator to iterate, ofcourse in this use-case the state of the container isn't meant to change whilst iteration is going on.

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  • Spring security - same page to deliver different content based on user role

    - by Ramesh
    Hello, i tried to search for any previous post related to my issue but couldnt find any. I have a scenario where in page handles 3 different scenarios and one of them not working. This page returns different content depending on if the user is authenticated or anonymous. localhost:8080/myApp/muUrl?test=authenticatedContent - used for Scenario 1 & 2 localhost:8080/myApp/muUrl?test=anonymousContent - used for Scenario 3 Scenario: 1) Authenticated user accesing the page url - the user gets displayed correct information. Works fine 2) Anonymous user accesing page URL with parameters that requires authentication - If anonymous, there is second level of check on the content they are accessing. for example, based on the GET parameters, there is custom logic to determine if the user has to be authenticated. In which case the page gets redirected to login page (WORKS fine). 3) Anonymous user accessing page URL with parameters that doesnt need authentication - in this case i get the SAvedRequest and redirect to the URL which is taking me to an infinite loop. Am i missing something very obvious or is there a way in AuthenticationProcessFilterEntryPoint to say "DON'T redirect to LOGIN page but process it" ? thanks.

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  • Set Renderbuffer Width and Height (Open GL ES)

    - by Josh Elsasser
    I'm currently experiencing an issue with an Open GL ES renderbuffer where the backing and width are are both set to 15. Is there any way to set them to the width of 320 and 480? My project is built up on Apple's EAGLView class and ES1Renderer, but I've moved it from the app delegate to a controller. I also moved the CADisplayLink outside of it (I update my game logic with the timestamp from this) Any help would be greatly appreciated. I add the glview to the window as follows: CGRect applicationFrame = [[UIScreen mainScreen] applicationFrame]; [window addSubview:gameController.glview]; [window makeKeyAndVisible]; I synthesize the controller and the glview within it. The EAGLView and Renderer are otherwise unmodified. Renderer Initialization: // Get the layer CAEAGLLayer *eaglLayer = (CAEAGLLayer *)self.layer; eaglLayer.opaque = TRUE; eaglLayer.drawableProperties = [NSDictionary dictionaryWithObjectsAndKeys: [NSNumber numberWithBool:FALSE], kEAGLDrawablePropertyRetainedBacking, kEAGLColorFormatRGBA8, kEAGLDrawablePropertyColorFormat, nil]; renderer = [[ES1Renderer alloc] init]; Render "resize from layer" Method - (BOOL)resizeFromLayer:(CAEAGLLayer *)layer { // Allocate color buffer backing based on the current layer size glBindRenderbufferOES(GL_RENDERBUFFER_OES, colorRenderbuffer); [context renderbufferStorage:GL_RENDERBUFFER_OES fromDrawable:layer]; glGetRenderbufferParameterivOES(GL_RENDERBUFFER_OES, GL_RENDERBUFFER_WIDTH_OES, &backingWidth); glGetRenderbufferParameterivOES(GL_RENDERBUFFER_OES, GL_RENDERBUFFER_HEIGHT_OES, &backingHeight); NSLog(@"Backing Width:%i and Height: %i", backingWidth, backingHeight); if (glCheckFramebufferStatusOES(GL_FRAMEBUFFER_OES) != GL_FRAMEBUFFER_COMPLETE_OES) { NSLog(@"Failed to make complete framebuffer object %x", glCheckFramebufferStatusOES(GL_FRAMEBUFFER_OES)); return NO; } return YES; }

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  • Rails - Help scoring an online quiz in RoR

    - by ChrisWesAllen
    I'm trying to grade a quiz application I would like to make. I have a questions model with and ask(the actual question), 4 choices(a-d), and a correct answer(string). In the view I have the 4 question being diplayed then the correct answer choice (This is just a test for functionality) and then I created a text_field to accept the users answer choice and a button to refresh the index action which has the scoring logic, for now.. --Do I need to put the text_field within a form_tag? <p>1. <%= h @question.q1 %></p> <p>2. <%= h @question.q2 %></p> <p>3. <%= h @question.q3 %></p> <p>4. <%= h @question.q4 %></p> <p>Answer: <%= h @question.correct %></p> <%= text_field_tag :choice, params[:choice] %> <%= button_to "Grade", {:controller => 'site', :action => "index"} %> <p> <%= @answer %></p> Heres the index controller action def index @question = Question.find(1) if @question.correct == params[:choice] @answer = 'right' else @answer = 'wrong' end end Its not really working. The textfield is supposed to take a letter choice like 'a' or 'c' and compare it with the correct answer in the database. I would love this to work by radiobuttons, but I'm a newbie to rails so I thought I'd take baby steps. So if anyone can help me with how to fix this by string, or preferably by radiobuttons, I'd really appreciate it.

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  • Object Design: How to Organize/Structure a "Collection Class"

    - by CrimsonX
    I'm currently struggling to understand how I should organize/structure a class which I have already created. The class does the following: As its input in the constructor, it takes a collection of logs In the constructor it validates and filters the logs through a series of algorithms implementing my business logic After all filtering and validation is complete, it returns a collection (a List) of the valid and filtered logs which can be presented to the user graphically in a UI. Here is some simplified code describing what I'm doing: class FilteredCollection { public FilteredCollection( SpecialArray<MyLog> myLog) { // validate inputs // filter and validate logs in collection // in end, FilteredLogs is ready for access } Public List<MyLog> FilteredLogs{ get; private set;} } However, in order to access this collection, I have to do the following: var filteredCollection = new FilteredCollection( secialArrayInput ); //Example of accessing data filteredCollection.FilteredLogs[5].MyLogData; Other key pieces of input: I foresee only one of these filtered collections existing in the application (therefore should I make it a static class? Or perhaps a singleton?) Testability and flexibility in creation of the object is important (Perhaps therefore I should keep this an instanced class for testability?) I'd prefer to simplify the dereferencing of the logs if at all possible, as the actual variable names are quite long and it takes some 60-80 characters to just get to the actual data. My attempt in keeping this class simple is that the only purpose of the class is to create this collection of validated data. I know that there may be no "perfect" solution here, but I'm really trying to improve my skills with this design and I would greatly appreciate advice to do that. Thanks in advance.

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  • Spawning a thread in python

    - by morpheous
    I have a series of 'tasks' that I would like to run in separate threads. The tasks are to be performed by separate modules. Each containing the business logic for processing their tasks. Given a tuple of tasks, I would like to be able to spawn a new thread for each module as follows. from foobar import alice, bob charles data = getWorkData() # these are enums (which I just found Python doesn't support natively) :( tasks = (alice, bob, charles) for task in tasks # Ok, just found out Python doesn't have a switch - @#$%! # yet another thing I'll need help with then ... switch case alice: #spawn thread here - how ? alice.spawnWorker(data) No prizes for guessing I am still thinking in C++. How can I write this in a Pythonic way using Pythonic 'enums' and 'switch'es, and be able to run a module in a new thread. Obviously, the modules will all have a class that is derived from a ABC (abstract base class) called Plugin. The spawnWorker() method will be declared on the Plugin interface and defined in the classes implemented in the various modules. Maybe, there is a better (i.e. Pythonic) way of doing all this?. I'd be interested in knowing

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  • Android NDK import-module / code reuse

    - by Graeme
    Morning! I've created a small NDK project which allows dynamic serialisation of objects between Java and C++ through JNI. The logic works like this: Bean - JavaCInterface.Java - JavaCInterface.cpp - JavaCInterface.java - Bean The problem is I want to use this functionality in other projects. I separated out the test code from the project and created a "Tester" project. The tester project sends a Java object through to C++ which then echo's it back to the Java layer. I thought linking would be pretty simple - ("Simple" in terms of NDK/JNI is usually a day of frustration) I added the JNIBridge project as a source project and including the following lines to Android.mk: NDK_MODULE_PATH=.../JNIBridge/jni/" JNIBridge/jni/JavaCInterface/Android.mk: ... include $(BUILD_STATIC_LIBRARY) JNITester/jni/Android.mk: ... include $(BUILD_SHARED_LIBRARY) $(call import-module, JavaCInterface) This all works fine. The C++ files which rely on headers from JavaCInterface module work fine. Also the Java classes can happily use interfaces from JNIBridge project. All the linking is happy. Unfortunately JavaCInterface.java which contains the native method calls cannot see the JNI method located in the static library. (Logically they are in the same project but both are imported into the project where you wish to use them through the above mechanism). My current solutions are are follows. I'm hoping someone can suggest something that will preserve the modular nature of what I'm trying to achieve: My current solution would be to include the JavaCInterface cpp files in the calling project like so: LOCAL_SRC_FILES := FunctionTable.cpp $(PATH_TO_SHARED_PROJECT)/JavaCInterface.cpp But I'd rather not do this as it would lead to me needing to update each depending project if I changed the JavaCInterface architecture. I could create a new set of JNI method signatures in each local project which then link to the imported modules. Again, this binds the implementations too tightly.

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  • Sending buffered images between Java client and Twisted Python socket server

    - by PattimusPrime
    I have a server-side function that draws an image with the Python Imaging Library. The Java client requests an image, which is returned via socket and converted to a BufferedImage. I prefix the data with the size of the image to be sent, followed by a CR. I then read this number of bytes from the socket input stream and attempt to use ImageIO to convert to a BufferedImage. In abbreviated code for the client: public String writeAndReadSocket(String request) { // Write text to the socket BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream())); bufferedWriter.write(request); bufferedWriter.flush(); // Read text from the socket BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream())); // Read the prefixed size int size = Integer.parseInt(bufferedReader.readLine()); // Get that many bytes from the stream char[] buf = new char[size]; bufferedReader.read(buf, 0, size); return new String(buf); } public BufferedImage stringToBufferedImage(String imageBytes) { return ImageIO.read(new ByteArrayInputStream(s.getBytes())); } and the server: # Twisted server code here # The analog of the following method is called with the proper client # request and the result is written to the socket. def worker_thread(): img = draw_function() buf = StringIO.StringIO() img.save(buf, format="PNG") img_string = buf.getvalue() return "%i\r%s" % (sys.getsizeof(img_string), img_string) This works for sending and receiving Strings, but image conversion (usually) fails. I'm trying to understand why the images are not being read properly. My best guess is that the client is not reading the proper number of bytes, but I honestly don't know why that would be the case. Side notes: I realize that the char[]-to-String-to-bytes-to-BufferedImage Java logic is roundabout, but reading the bytestream directly produces the same errors. I have a version of this working where the client socket isn't persistent, ie. the request is processed and the connection is dropped. That version works fine, as I don't need to care about the image size, but I want to learn why the proposed approach doesn't work.

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  • Parallel.Foreach loop creating multiple db connections throws connection errors?

    - by shawn.mek
    Login failed. The login is from an untrusted domain and cannot be used with Windows authentication I wanted to get my code running in parallel, so I changed my foreach loop to a parallel foreach loop. It seemed simple enough. Each loop connects to the database, looks up some stuff, performs some logic, adds some stuff, closes the connection. But I get the above error? I'm using my local sql server and entity framework (each loop uses it's own context). Is there some problem with connecting multiple times using the same local login or something? How did I get around this? I have (before trying to covert to a parallel.foreach loop) split my list of objects that I am foreach looping through into four groups (separate csv files) and run four concurrent instances of my program (which ran faster overall than just one, thus the idea for parallel). So it seems connecting to the db shouldn't be a problem? Any ideas? EDIT: Here's before var gtgGenerator = new CustomGtgGenerator(); var connectionString = ConfigurationManager.ConnectionStrings["BioEntities"].ConnectionString; var allAccessionsFromObs = _GetAccessionListFromDataFiles(collectionId); ForEach(cloneIdAndAccessions in allAccessionsFromObs) DoWork(gtgGenerator, taxonId, organismId, cloneIdAndAccessions, connectionString)); after var gtgGenerator = new CustomGtgGenerator(); var connectionString = ConfigurationManager.ConnectionStrings["BioEntities"].ConnectionString; var allAccessionsFromObs = _GetAccessionListFromDataFiles(collectionId); Parallel.ForEach(allAccessionsFromObs, cloneIdAndAccessions => DoWork(gtgGenerator, taxonId, organismId, cloneIdAndAccessions, connectionString)); Inside the DoWork I use the BioEntities using (var bioEntities = new BioEntities(connectionString)) {...}

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  • How to compare two file structures in PHP?

    - by OM The Eternity
    I have a function which gives me the complete file structure upto n-level, function getDirectory($path = '.', $ignore = '') { $dirTree = array (); $dirTreeTemp = array (); $ignore[] = '.'; $ignore[] = '..'; $dh = @opendir($path); while (false !== ($file = readdir($dh))) { if (!in_array($file, $ignore)) { if (!is_dir("$path/$file")) { //display of file and directory name with their modification time $stat = stat("$path/$file"); $statdir = stat("$path"); $dirTree["$path"][] = $file. " === ". date('Y-m-d H:i:s', $stat['mtime']) . " Directory == ".$path."===". date('Y-m-d H:i:s', $statdir['mtime']) ; } else { $dirTreeTemp = getDirectory("$path/$file", $ignore); if (is_array($dirTreeTemp))$dirTree = array_merge($dirTree, $dirTreeTemp); } } } closedir($dh); return $dirTree; } $ignore = array('.htaccess', 'error_log', 'cgi-bin', 'php.ini', '.ftpquota'); //function call $dirTree = getDirectory('.', $ignore); //file structure array print print_r($dirTree); Now here my requirement is , I have two sites The Development/Test Site- where i do testing of all the changes The Production Site- where I finally post all the changes as per test in development site Now, for example, I have tested an image upload in the Development/test site, and i found it appropriate to publish on Production site then i will completely transfer the Development/Test DB detail to Production DB, but now I want to compare the files structure as well to transfer the corresponding image file to Production folder. There could be the situation when I update the image by editing the image and upload it with same name, now in this case the image file would be already present there, which will restrict the use of "file_exist" logic, so for these type of situations....HOW CAN I COMPARE THE TWO FILE STRUCTURE TO GET THE SYNCHRONIZATION DONE AS PER REQUIREMENT??

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  • LINQ to SQL: Reusable expression for property?

    - by coenvdwel
    Pardon me for being unable to phrase the title more exact. Basically, I have three LINQ objects linked to tables. One is Product, the other is Company and the last is a mapping table Mapping to store what Company sells which products and by which ID this Company refers to this Product. I am now retrieving a list of products as follows: var options = new DataLoadOptions(); options.LoadWith<Product>(p => p.Mappings); context.LoadOptions = options; var products = ( from p in context.Products select new { ProductID = p.ProductID, //BackendProductID = p.BackendProductID, BackendProductID = (p.Mappings.Count == 0) ? "None" : (p.Mappings.Count > 1) ? "Multiple" : p.Mappings.First().BackendProductID, Description = p.Description } ).ToList(); This does a single query retrieving the information I want. But I want to be able to move the logic behind the BackendProductID into the LINQ object so I can use the commented line instead of the annoyingly nested ternary operator statements for neatness and re-usability. So I added the following property to the Product object: public string BackendProductID { get { if (Mappings.Count == 0) return "None"; if (Mappings.Count > 1) return "Multiple"; return Mappings.First().BackendProductID; } } The list is still the same, but it now does a query for every single Product to get it's BackendProductID. The code is neater and re-usable, but the performance now is terrible. What I need is some kind of Expression or Delegate but I couldn't get my head around writing one. It always ended up querying for every single product, still. Any help would be appreciated!

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  • Can't seem to get .Union to work (merging 2 array's together, exclude duplicates)

    - by D. Veloper
    I want to combine two array's, excluding duplicates. I am using a custom class: public class ArcContact : IEquatable<ArcContact> { public String Text; public Boolean Equals(ArcContact other) { if (Object.ReferenceEquals(other, null)) return false; if (Object.ReferenceEquals(this, other)) return true; return Text.Equals(other.Text); } public override Int32 GetHashCode() { return Text == null ? 0 : Text.GetHashCode(); } } I implemented and the needed IEquatable interface as mentioned in this msdn section. I only want to check the Text property of the ArcContact class and make sure an Array of ArcContact have an unique Text. Here I pasted the code that I use, as you can see I have method with two parameters, array's to combine and below that the code I got from the previous mentioned msdn section. internal static class ArcBizz { internal static ArcContact[] MergeDuplicateContacts(ArcContact[] contacts1, ArcContact[] contacts2) { return (ArcContact[])contacts1.Union(contacts2); } internal static IEnumerable<T> Union<T>(this IEnumerable<T> a, IEnumerable<T> b); } What am I doing wrong?

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  • jQuery AJAX chained calls + Celery in Django

    - by user1029968
    Currently clicking one of the links in my application, triggers AJAX call (GET) that - if succeeds - triggers the second one and this second one - if succeeds - calls the third one. This way user can be informed which part of process started when clicking the link is currently ongoing. So in the template file in Django project, click callback body for link mentioned looks like below: $("#the-link").click(function(item)) { // CALL 1 $.ajax({ url: {% url ajax_call_1 %}, data: { // something } }) .done(function(call1Result) { // CALL 2 $.ajax({ url: {% url ajax_call_1 %}, data: { // call1Result passed here to CALL 2 } }) .done(function(call2Result) { // CALL 3 $.ajax({ url: {%url ajax_call_3 %}, data: { // call2Result passed here to CALL 3 } }) .done(function(call3Result) { // expected result if everything went fine console.log("wow, it worked!"); console.log(call3Result); }) .fail(function(errorObject) { console.log("call3 failed"); console.log(errorObject); } }) .fail(function(errorObject)) { console.log("call2 failed"); console.log(errorObject); } }) .fail(function(errorObject) { console.log("call1 failed"); console.log(errorObject); }); }); This works fine for me. The thing is, I'd like to prevent interrupting the following calls if the user closes the browser and the calls are not finished (as it will take some time to finish all three), as there is some additional logic in Django view functions called in each GET request. For example, if user clicks the link and closes the browser during CALL 1, is it possible to somehow go on with the following CALL 2 and CALL 3? I know that normally I'd be able to use Celery Task to process the function but is it still possible here with the chained calls mentioned? Any help is much appreciated!

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  • Some languages don't work when using Word 2007 Spellcheck from Interop

    - by Tridus
    I'm using the Word 2007 spellchecker via Interop in a VB.net desktop app. When using the default language (English), it works fine. If I set the language to French via LanguageId, it also works. But if I set it to French (Canadian) (Word.WdLanguageID.wdFrenchCanadian), it doesn't work. There's no error message, it simply runs and says the document contains no errors. I know it does, if I paste the exact same text into Word itself and run it with the French (Canadian) dictionary, it finds errors. Just why that dictionary doesn't work is kind of a mystery to me. Full code below: Public Shared Function SpellCheck(ByVal text As String, ByVal checkGrammar As Boolean) As String ' If there is no data to spell check, then exit sub here. If text.Length = 0 Then Return text End If Dim objWord As Word.Application Dim objTempDoc As Word.Document ' Declare an IDataObject to hold the data returned from the ' clipboard. Dim iData As IDataObject objWord = New Word.Application() objTempDoc = objWord.Documents.Add objWord.Visible = False ' Position Word off the screen...this keeps Word invisible ' throughout. objWord.WindowState = 0 objWord.Top = -3000 ' Copy the contents of the textbox to the clipboard Clipboard.SetDataObject(text) ' With the temporary document, perform either a spell check or a ' complete ' grammar check, based on user selection. With objTempDoc .Content.Paste() .Activate() .Content.LanguageID = Word.WdLanguageID.wdFrenchCanadian If checkGrammar Then .CheckGrammar() Else .CheckSpelling() End If ' After user has made changes, use the clipboard to ' transfer the contents back to the text box .Content.Copy() iData = Clipboard.GetDataObject If iData.GetDataPresent(DataFormats.Text) Then text = CType(iData.GetData(DataFormats.Text), _ String) End If .Saved = True .Close() End With objWord.Quit() Return text End Function

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  • Visual Studio / Blend... how you organize that?

    - by TomTom
    Virst time more complex stuff in WPF. I am a little lost on the split betwen VS and Blend. It seems I am VERY limited with editors in Visual Studio for editing controls - when customizing, for example, it seems I Can enter astyle in XML... but in blend I Can tell it to make a copy of the CURRENT style and use that as a starter, definitely more convenient. I understand the "difference in focus", but it seems to me that i Really need both tools to work, especially if the controls I Do are: More complex Not user controls "on purpose" (to allow more customization by programmes using the application). THis means when I do a control, my approach would be: Work on the backend as good as it gets without front end (i.e. implement all methods needed etc., but can be dummies) Switch over to Blend (closing visual studio - as the projcet must be closed) Put in the initial templating Switch over to VIsual Studio (closing blend) Put logic in and debug. This seems pretty counterintuitively. Am I missing something obvious here?

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