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  • How to crete a Java Iterator that throws IOException

    - by Antonio
    I'd like to implement an iterator that retrieves objects from disk/network. Iterator itr = getRemoteIterator(); while(itr.hasNext()) { Object element = itr.next(); System.out.print(element + " "); } However the problem is that hasNext() and next() methods of the Iterator object does not allow to throw IOException. Is there any other standard interface work around this issue? Desired code is: public interface RemoteIterator<E> { boolean hasNext() throws IOException; E next() throws IOException; void remove(); }

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  • Access static constant variable from multiple threads in C

    - by user325519
    I have some experience with multithread programming under Linux (C/C++ & POSIX threads), however most obvious cases are sometimes very complicated. I have several static constant variables (global and function local) in my code, can I access them simultaneously from multiple threads without using mutexes? Because I don't modify them it should be ok, but it's always better to ask. I have to do heavy speed optimization, so even as fast operations as mutex lock/unlock are quite expensive for me, especially because my application is going to access these variables form long loops.

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  • Reading files with Java

    - by sikas
    I would like to know how can I read a file byte by byte then perform some operation every n bytes. for example: Say I have a file of size = 50 bytes, I want to divide it into blocks each of n bytes. Then each block is sent to a function for some operations to be done on those bytes. The blocks are to be created during the read process and sent to the function when the block reaches n bytes so that I don`t use much memory for storing all blocks. I want the output of the function to be written/appended on a new file. This is what I've reached to read, yet I don't know it it is right: fc = new JFileChooser(); File f = fc.getSelectedFile(); FileInputStream in = new FileInputStream(f); byte[] b = new byte[16]; in.read(b); I haven't done anything yet for the write process.

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  • How to avoid Mercurial repo corruption when sharing a repository between Windows/Mac?

    - by Stabledog
    I have several projects which are shared between Windows and Mac. The dev machine is a Mac running Parallels: the files are stored on the Mac side, and the source is shared to the Windows side. This is very convenient, as I can switch back and forth between Windows and Mac tools rapidly without having to sync files. Recently I switched from Subversion to Mercurial, and now I'm having problems with the Mercurial repository becoming corrupt if I use the Windows tools to add/update, etc. I have to be very careful about which operations on the Windows side are safe (mainly the read-only stuff) and of course I forget rather regularly. Does anybody know why the corruption occurs? I thought Mercurial repositories were platform-agnostic. Any ideas how to prevent it without removing the Windows tools entirely?

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  • Even lighter than SQLite

    - by Richard Fabian
    I've been looking for a C++ SQL library implementation that is simple to hook in like SQLite, but faster and smaller. My projects are in games development and there's definitely a cutoff point between needing to pass the ACID test and wanting some extreme performance. I'm willing to move away from SQL string style queries, allowing it to be code driven, but I haven't found anything out there that provides SQL like flexibility while also preferring performance over the ACID test. I don't want to go reinventing the wheel, and the idea of implementing an SQL library on my own is quite daunting, even if it's only going to be simple subset of all the calls you could make. I need the basic commands (SELECT, MODIFY, DELETE, INSERT, with JOIN, and WHERE), not data operations (like sorting, min, max, count) and don't need the database to be atomic, or even enforce consistency (I can use a real SQL service while I'm testing and debugging).

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  • VB.NET Use WebRequest to check if URI is valid

    - by Robbo
    Looking for the best way to determine if a URI exists in VB.NET without downloading the actual content. System.IO.FileExists/My.Computer.FileSystem.FileExists can be used locally to determine if a file exists, is there an equivalent for the Web? Currently I am using a HttpWebRequest to check URI existance using the ResponseStream. This populates the stream if the target does exist and throws an exception if it doesn't. The function is being expanded to also check for PDF files (typically 5MB +), images, etc and it will be a waste of time/bandwidth to actually populate the content into a stream. In the case of "Success" (the target does exist) I do not wish to download the file or page, simply to end up with a Boolean which indicates the whether something exists at the end of this URI.

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  • Construction an logical expression which will count bits in a byte.

    - by danatel
    When interviewing new candidates, we usually ask them to write a piece of C code to count the number of bits with value 1 in a given byte variable (e.g. the byte 3 has two 1-bits). I know all the common answers, such as right shifting eight times, or indexing constant table of 256 precomputed results. But, is there a smarter way without using the precomputed table? What is the shortest combination of byte operations (AND, OR, XOR, +, -, binary negation, left and right shift) which computes the number of bites?

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  • JavaScript pack("d") - binary strings

    - by Tim Whitlock
    I'm trying to replicate the Perl and PHP style pack and unpack functions in JavaScript. Unsigned integers were easy enough, so my pack('n') and pack('N') are ok. But my lack of a computer science background is a hurdle now and I don't know where to start with pack('d') for packing JavaScript's standard floating point. Is there a JavaScript library for this out there? If not, is there a good resource where I can learn how to do this? I am fine with bitwise and binary level operations in JS, I just don't know where to start with the logic. Thanks.

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  • Copying a database into a new database including structure and data

    - by Jason
    In phpMyAdmin under operations I can "Copy database to:" and select Structure and data CREATE DATABASE before copying Add AUTO_INCREMENT value I need to be able to do that without using phpMyAdmin. I know how to create the database and user. I have a source database that's a shell that I can work from so all I really need is the how to copy all the table structure and data part. (I know, the harder part) system() & exec() are not options for me which rules out mysqldump. (I think) How can I loop through each table and recreate it's structure and data? Is it just looping through the results of SHOW TABLES then for each table looping through DESCRIBE tablename Then, is there an easy way for getting the data copied?

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  • How listview delete data in database

    - by Bud33
    I have a problem to delete data in listview, I was able to delete data in listview select record, but data which selected is not deleted in the database, I have a source code Private _updateinputalltrans As Boolean Private Sub btndelete_Click(sender As System.Object, e As System.EventArgs) Handles btndelete.Click With Me.listviewpos.SelectedItem .Remove() End With MessageBox.Show("Are you sure delete this record?", "Confirmation", MessageBoxButtons.YesNo, MessageBoxIcon.Exclamation, New EventHandler(AddressOf DeleteData)) End Sub Private Sub DeleteData(ByVal sender As Object, ByVal e As EventArgs) Dim conn As New Connection(Connectiondb) If Me.updateinputalltrans = False Then If Me.listviewpos.Items.Count > 0 Then For Each del As ListViewItem In listviewpos.Items conn.delete_dtpospart(del.Text) Next End If End If End Sub delete_dtpospart a declare which connection to the database using a stored procedure

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  • Calling asynchronous methods from wcf service

    - by hima
    In my asp.net application, I am using wcf service to get all the business logic. I am using that service reference in my application to work with that. Now adding that service reference is giving another option Update service reference is giving Generate asynchronous operations. If I check the option and add the service will it generate asynchronous methods for my existing service. If so how do I use the metohd. Let me know the way for that. Thanks, Hima.

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  • cleartool question

    - by chuanose
    Lets say I have a directory at \testfolder, and the latest is currently at /main/10. I know that the operation resulting in testfolder@@/main/6 is to remove a file named test.txt. What's a sequence of cleartool operations that can be done in a script that will take "testfolder@@/main/6" and "test.txt" as input, and will cat out the contents of test.txt as of that time? One way I can think of is to get the time of /main/6 operation, create a view with config spec -time set to that time, and then cat the test.txt at the directory. But I'm wondering if I can do this in a easier way that doesn't involve manipulating config specs, perhaps through "cleartool find" and extended path names

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  • python parallel computing: split keyspace to give each node a range to work on

    - by MatToufoutu
    My question is rather complicated for me to explain, as i'm not really good at maths, but i'll try to be as clear as possible. I'm trying to code a cluster in python, which will generate words given a charset (i.e. with lowercase: aaaa, aaab, aaac, ..., zzzz) and make various operations on them. I'm searching how to calculate, given the charset and the number of nodes, what range each node should work on (i.e.: node1: aaaa-azzz, node2: baaa-czzz, node3: daaa-ezzz, ...). Is it possible to make an algorithm that could compute this, and if it is, how could i implement this in python? I really don't know how to do that, so any help would be much appreciated

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  • How to optimize indexing of large number of DB records using Zend_Lucene and Zend_Paginator

    - by jdichev
    So I have this cron script that is deployed and ran using Cron on a host and indexes all the records in a database table - the index is later used both for the front end of the site and the backed operations as well. After the operation, the index is about 3-4 MB. The problem is it takes a lot of resources (CPU: 30+ and a good chunk of memory) and slows the machine down. My question is about how to optimize the operation described below: First there is a select query built using the Zend Framework API, this query is then passed to a Paginator factory that returns a paginator which I am using to balance the current number of items being indexed and not iterate over too much items. The script is iterating over the current items in the paginator object using a foreach loop until reaching the end and then it starts from the beginning after getting items for the next page. I am suspecting this overhead is caused by the Zend_Lucene but no idea how this could be improved.

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  • How to detect if breaking an edge will make a graph disjoint?

    - by the_graph_guy
    I have a graph that starts off with a single, root node. Nodes are added one by one to the graph. At node creation time, they have to be linked either to the root node, or to another node, by a single edge. Edges can also be created and deleted (one by one, between any two nodes). Nodes can be deleted one at a time. Node and edge creation, deletion operations can happen in any arbitrary order. OK, so here's my question: When an edge is deleted, is it possible do determine, in constant time (i.e. with an O(1) algorithm), if doing this will divide the graph into two disjoint subgraphs? If it will, then which side of the edge will the root node belong? I'm willing to maintain, within reasonable limits, any additional data structure that can facilitate the derivation of this information. Maybe it is not possible to do it in O(1), if so any pointers to literature will be appreciated.

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  • IDL-like parser that turns a document definition into powerful classes?

    - by paniq
    I am looking for an IDL-like (or whatever) translator which turns a DOM- or JSON-like document definition into classes which are accessible from both C++ and Python, within the same application expose document properties as ints, floats, strings, binary blobs and compounds: array, string dict (both nestable) (basically the JSON type feature set) allow changes to be tracked to refresh views of an editing UI provide a change history to enable undo/redo operations can be serialized to and from JSON (can also be some kind of binary format) allow to keep large data chunks on disk, with parts only loaded on demand provide non-blocking thread-safe read/write access to exchange data with realtime threads allow multiple editors in different processes (or even on different machines) to view and modify the document The thing that comes closest so far is the Blender 2.5 DNA/RNA system, but it's not available as a separate library, and badly documented. I'm most of all trying to make sure that such a lib does not exist yet, so I know my time is not wasted when I start to design and write such a thing. It's supposed to provide a great foundation to write editing UI components.

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  • ASP.MVC ModelBinding Behaviour

    - by OldBoy
    This one has me stumped, despite the numerous posts on here. The scenario is a basic MVC(2) web application with simple CRUD operations. Whenever the edit form is submitted and the UpdateModel() called, an exception is thrown: System.Data.Linq.ForeignKeyReferenceAlreadyHasValueException was unhandled by user code This occurs against a DropDownList value which is a foreign key on the entity table. However, there is another DropDownList list on the form, representing another foreign key, which does not throw the error (unsurprisingly). Changing the property values manually inside the Edit Action: Recipe recipe = repository.GetRecipe(int.Parse(formValues["recipeid"])); recipe.CategoryId = Convert.ToInt32(formValues["CategoryId"].ToString()); recipe.Page = int.Parse(formValues["Page"].ToString()); recipe.PublicationId=Convert.ToInt32(formValues["PublicationId"].ToString()); Allows the CategoryId and Page properties to be updated, and then the error is thrown on the PublicationId. All of the referential integrity is checked an the same in the db and the dbml. Any light shed on this would be most welcome.

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  • Invalidating UITableView contents

    - by Roman
    I have an application with several UITableViewControllers. Now, the user is allowed to change "Data source". In that case I need to invalidate (reset) data in the relevant UITableViews. I figured out, that I can use NSNotificationCenter and add these controllers as observers to events which will be generated when the data source changes. The question is, how do I reset the underlying tables? I can, of course, set some boolean flag, and call UITableView:reloadData in viewWillAppear or viewDidAppear, but I was wondering, if there's a cleaner way of doing it. Or perhaps I'm completely missing the point, and I don't need NSNotificationCenter altogether. Thank you very much in advance.

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  • How to integrate Python scripting in my Android App (like SL4A)

    - by Seraphim's host
    I need to add scripting layer to my android App. So I can remotely prepare a script that my app download form a web service and execute on the user device. I found a interesting project called Scripting Layer for Android (SL4A) here: http://code.google.com/p/android-scripting/ I'm not sure I can execute Python script without installing the PythonForAndroid_r4.apk first. I can't force my customer to install that application! So my question is, can the SL4A layer be integrated in my app without the need to install other apk? I need to execute actions like update data in the DB, create/read/delete a file on the sd card... Not so complex but I see SL4A can do a lot of things like these. Other scripting libraries? EDIT: Found also MVEL: http://mvel.codehaus.org/ but I think it needs to be integrated to execute complex operations like accessing a DB...

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  • find all occurrences of comparison with == in visual studio

    - by Emiswelt
    Hi there I made the mistake of using == for comparing IP addresses instead of using the equals() method of the IPAddress class in C#, which will result in the comparison of references instead of values. Since the solution I am currently working on is very large for a one-man project ( 100.000 lines of source code), I am very sure that I still have some of these wrong statements in my code. Is there any possibility to tell Visual Studio to find all occurrences of == operations on a specific class for me, so that I can find and clean up the bugged comparisons? with best regards, emi

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  • UIRotationGestureRecognizer changes with CGAffineTransformMakeScale

    - by user523234
    A view is flipped using this: self.transform = CGAffineTransformMakeScale(-1, 1); // self is an UIView To rotate this view: -(void)handleRotate:(UIRotationGestureRecognizer *)recognizer { recognizer.view.transform = CGAffineTransformRotate(recognizer.view.transform, recognizer.rotation); recognizer.rotation = 0; } The issue is that after the view is flipped so is the rotation's direction. Any solution how to fix this? Edit: My current solution is using a boolean and negate the recognizer.rotation value in handleRotate method. But I am still looking for the technical solution.

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  • PrivateFontCollection fails on appharbor

    - by grennis
    I am trying to load a custom font (ttf file) and draw into an image with the Graphics object. This code runs fine locally: PrivateFontCollection fonts = new PrivateFontCollection(); string path = context.Server.MapPath("~/App_Data/Futura LT Bold.ttf"); if (!System.IO.File.Exists(path)) { throw new InvalidOperationException("Font file is not deployed: " + path); } fonts.AddFontFile(path); However when run on appharbor, the call to AddFontFile fails with the exception: System.ArgumentException: Font 'Futura LT Book' does not support style 'Regular'. at System.Drawing.Font.CreateNativeFont() at System.Drawing.Font.Initialize(FontFamily family, Single emSize, FontStyle style, GraphicsUnit unit, Byte gdiCharSet, Boolean gdiVerticalFont) at System.Drawing.Font..ctor(FontFamily family, Single emSize) at LumenboxWeb.Controllers.GalleryController.FontTest() in d:\temp\h5oqslma.udd\input\src\LumenboxWeb\Controllers\GalleryController.cs:line 59 at lambda_method(Closure , ControllerBase , Object[] ) at System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) I have tried different fonts, and they all work locally, but none work on appharbor. Is it possible to load fonts dynamically on appharbor?

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  • How to add the UAC shield icon to program that still must target XP?

    - by bsruth
    I have a program that still must target Windows XP (_WIN32_WINNT 0x501), as most of our customers still use XP. However, we have been shipping Vista for a while, and are now pushing Windows 7 upgrades. For the software to work correctly on the newer OSs, there are a couple operations that require UAC elevation. I have the elevation code working, but would like to have the UAC icon present on the buttons that launch the UAC process. Unfortunately, all of the options defined in Microsoft's UAC UI document require _WIN32_WINNT 0x600 or newer. Is there any way to get the appropriate UAC icon (Vista and 7 use different ones) to show on the button while still being able to target XP (where no icon will be shown)? I'm using C++, but may be able to adapt a .NET solution.

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  • Faking a Single Address Space

    - by dsimcha
    I have a large scientific computing task that parallelizes very well with SMP, but at too fine grained a level to be easily parallelized via explicit message passing. I'd like to parallelize it across address spaces and physical machines. Is it feasible to create a scheduler that would parallelize already multithreaded code across multiple physical computers under the following conditions: The code is already multithreaded and can scale pretty well on SMP configurations. The fact that not all of the threads are running in the same address space or on the same physical machine must be transparent to the program, even if this comes at a significant performance penalty in some use cases. You may assume that all of the physical machines involved are running operating systems and CPU architectures that are binary compatible. Things like locks and atomic operations may be slow (having network latency to deal with and all) but must "just work".

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  • How to display the found matches of preg_match function in PHP?

    - by Eric
    I am using the following to check if links exist on file.php: $fopen = fopen('file.php', 'r'); $fread = fread($fopen, filesize('file.php')); $pattern = "/^<a href=/i"; if (preg_match($pattern, $fread)) { echo 'Match Found'; } else { echo 'Match Not Found'; } if I echo preg_match($pattern, $fread) I get a boolean value, not the found matches. I tried what was on the php.net manual and did this: preg_match($pattern, $fread, $matches); then when I echoed $matches I got "Array" message. So I tried a foreach loop and when that didn't display anything I tried $matches[0] and that too outputted nothing. So how does one go about displaying the matches found?

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