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• External API function calls AS3 control timeline

  - by giles

  I have function problem using this code (below), the embedded flash movieclip disappears or completely prevents the scrollto.js query to function in DW cs3. Communication between Flash and JavaScript is without problems, it is the call back I can't find to work and more frustratingly, should be simple, as no values are not required. So far, this has been hours of scouring the net without a workable end in sight...ahrr. What is a function for this to work? JavaScript – to call Flash event from HTML button link, placed between head tags function callExternalInterface() var flashMovie = window.document.menu; flashMovie.menu_up(value); menu_up is the string. Does anyone know of workable function for callback?? HTML <div id="btn_up"><a href="#top" name="charDev" id="charDev" onclick="">top</a></div> Pane navigation div that uses Scrollto.js query, and it's this link I need calling back to the embedded "menubtns.swf" (nested in "AS3Menu_javascript.swf") to play 5 frames of this movieclip, via a JS function. Embedded .swf code, using swfobject.js with allowScriptAccess=always <object classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" name="menu"<br/> width="251" height="251" id="menu"> <param name="movie" value="../~Assets/Flash/AS3Menu_javascript.swf" /> <param name="allowScriptAccess" value="always" /> <param name="movie" value="ExternalInterfaceScript.swf" /> <param name="quality" value="high" /> <object type="application/x-shockwave-flash" data="../~Assets/Flash/AS3Menu_javascript.swf" width="250" height="250"> <p>Alternative content</p> </object> </object> AS3 / Flash import flash.external.ExternalInterface;flash.system.Security.allowDomain(/sourceDomain/); ExternalInterface.addCallBack("menu_up", this, resetmenu); function resetmenu(){ gotoAndPlay:("frame label" / "number") }

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• What are the primitive Forth operators?

  - by Barry Brown

  I'm interested in implementing a Forth system, just so I can get some experience building a simple VM and runtime. When starting in Forth, one typically learns about the stack and its operators (DROP, DUP, SWAP, etc.) first, so it's natural to think of these as being among the primitive operators. But they're not. Each of them can be broken down into operators that directly manipulate memory and the stack pointers. Later one learns about store (!) and fetch (@) which can be used to implement DUP, SWAP, and so forth (ha!). So what are the primitive operators? Which ones must be implemented directly in the runtime environment from which all others can be built? I'm not interested in high-performance; I want something that I (and others) can learn from. Operator optimization can come later. (Yes, I'm aware that I can start with a Turing machine and go from there. That's a bit extreme.) Edit: What I'm aiming for is akin to bootstrapping an operating system or a new compiler. What do I need do implement, at minimum, so that I can construct the rest of the system out of those primitive building blocks? I won't implement this on bare hardware; as an educational exercise, I'd write my own minimal VM.

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• Memory mapped files and "soft" page faults. Unavoidable?

  - by Robert Oschler

  I have two applications (processes) running under Windows XP that share data via a memory mapped file. Despite all my efforts to eliminate per iteration memory allocations, I still get about 10 soft page faults per data transfer. I've tried every flag there is in CreateFileMapping() and CreateFileView() and it still happens. I'm beginning to wonder if it's just the way memory mapped files work. If anyone there knows the O/S implementation details behind memory mapped files I would appreciate comments on the following theory: If two processes share a memory mapped file and one process writes to it while another reads it, then the O/S marks the pages written to as invalid. When the other process goes to read the memory areas that now belong to invalidated pages, this causes a soft page fault (by design) and the O/S knows to reload the invalidated page. Also, the number of soft page faults is therefore directly proportional to the size of the data write. My experiments seem to bear out the above theory. When I share data I write one contiguous block of data. In other words, the entire shared memory area is overwritten each time. If I make the block bigger the number of soft page faults goes up correspondingly. So, if my theory is true, there is nothing I can do to eliminate the soft page faults short of not using memory mapped files because that is how they work (using soft page faults to maintain page consistency). What is ironic is that I chose to use a memory mapped file instead of a TCP socket connection because I thought it would be more efficient. Note, if the soft page faults are harmless please note that. I've heard that at some point if the number is excessive, the system's performance can be marred. If soft page faults intrinsically are not significantly harmful then if anyone has any guidelines as to what number per second is "excessive" I'd like to hear that. Thanks.

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• Creative ways to punish (or just curb) laziness in coworkers

  - by FerretallicA

  Like the subject suggests, what are some creative ways to curb laziness in co-workers? By laziness I'm talking about things like using variable names like "inttheemplrcd" instead of "intEmployerCode" or not keeping their projects synced with SVN, not just people who use the last of the sugar in the coffee room and don't refill the jar. So far the two most effective things I've done both involve the core library my company uses. Since most of our programs are in VB.net the lack of case sensitivity is abused a lot. I've got certain features of the library using Reflection to access data in the client apps, which has a negligible performance hit and introduces case sensitivity in a lot places where it is used. In instances where we have an agreed standard which is compromised by blatant laziness I take it a step further, like the DatabaseController class which will blatantly reject any DataTable passed to it which isn't named dtSomething (ie- must begin with dt and third letter must be capitalised). It's frustrating to have to resort to things like this but it has also gradually helped drill more attention to detail into their heads. Another is adding some code to the library's initialisation function to display a big and potentially embarrassing (only if seen by a client) message advising that the program is running in debug mode. We have had many instances where projects are sent to clients built in debug mode which has a lot of implications for us (especially with regard to error recovery) and doing that has made sure they always build to release before distributing. Any other creative (ie- not StyleCop etc) approaches like this?

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• How to make Stack.Pop threadsafe

  - by user260197

  I am using the BlockingQueue code posted in this question, but realized I needed to use a Stack instead of a Queue given how my program runs. I converted it to use a Stack and renamed the class as needed. For performance I removed locking in Push, since my producer code is single threaded. My problem is how can thread working on the (now) thread safe Stack know when it is empty. Even if I add another thread safe wrapper around Count that locks on the underlying collection like Push and Pop do, I still run into the race condition that access Count and then Pop are not atomic. Possible solutions as I see them (which is preferred and am I missing any that would work better?): Consumer threads catch the InvalidOperationException thrown by Pop(). Pop() return a nullptr when _stack-Count == 0, however C++-CLI does not have the default() operator ala C#. Pop() returns a boolean and uses an output parameter to return the popped element. Here is the code I am using right now: generic <typename T> public ref class ThreadSafeStack { public: ThreadSafeStack() { _stack = gcnew Collections::Generic::Stack<T>(); } public: void Push(T element) { _stack->Push(element); } T Pop(void) { System::Threading::Monitor::Enter(_stack); try { return _stack->Pop(); } finally { System::Threading::Monitor::Exit(_stack); } } public: property int Count { int get(void) { System::Threading::Monitor::Enter(_stack); try { return _stack->Count; } finally { System::Threading::Monitor::Exit(_stack); } } } private: Collections::Generic::Stack<T> ^_stack; };

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• ajax delay load UserControl asp.net

  - by user196202

  regarding ajax delay load of usercontrols (or any controls) on Post at Encosia.com : http://encosia.com/2008/02/05/boost-aspnet-performance-with-deferred-content-loading/ I tried to implement it , but I noticed that it can be done only for simple controls or UserControls that Have simple asp.net controls (or html tags) . But when it involved with advanced dynamic ajax control (like ajaxControlToolkit or Telerik controls) that have javascripts inside them This method of injecting the html code to the .InnerHtml property of div tag (for example) IS NOT WORKING , and I red about it that The browser need to load the script on load and after that it won't iterperate the scripts injectd via .InnerHtml. So I attached here example of delay load project (from encosia.com by dave ward) with my modification (look at DefaultPopup.aspx and beforePopup.aspx and AfterPopup.aspx) Which I modified the RssReader to show listview with popup items (which is implemented via ACT HoverMenuExtender ) So in the regular way the popup items are shown right , but on the delay load which is done by creating virtual page for rendering the html and injecting it to .InnerHtml property – This ISN'T WORKING. So my question is : is there a way to do delay loading for controls which include scripts lik ACT and Telerik and others? And for the ajax templates – if I need to inject advanced control to the page – how I do it with your approach? Thanks very much (I can't attach here files so everyone please ask me by mail ([email protected]) and i'll send it to him. ) Zahi Kramer

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• Cloud-aware programming and help choosing a good framework

  - by Shoaibi

  How can i write a cloud-aware application? e.g. an application that takes benefit of being deployed on cloud. Is it same as an application that runs or a vps/dedicated server? if not then what are the differences? are there any design changes? What are the procedures that i need to take if i am to migrate an application to cloud-aware? Also i am about to implement a web application idea which would need features like security, performance, caching, and more importantly free. I have been comparing some frameworks and found that django has least RAM/CPU usage and works great in prefork+threaded mode, but i have also read that django based sites stop to respond with huge load of connections. Other frameworks that i have seen/know are Zend, CakePHP, Lithium/Cake3, CodeIgnitor, Symfony, Ruby on Rails.... So i would leave this to your opinion as well, suggest me a good free framework based on my needs. Finally thanks for reading the essay ;)

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• .NET Membership with Repository Pattern

  - by Zac

  My team is in the process of designing a domain model which will hide various different data sources behind a unified repository abstraction. One of the main drivers for this approach is the very high probability that these data sources will undergo significant change in the near future and we don't want to be re-writing business logic when this happens. One data source will be our membership database which was originally implemented using the default ASP.Net Membership Provider. The membership provider is tied to the System.Web.Security namespace but we have a design guideline requiring that our domain model layer is not dependent upon System.Web (or any other implementation/environment dependency) as it will be consumed in different environments - nor do we want our websites directly communicating with databases. I am considering what would be a good approach to reconciling the MembershipProvider approach with our abstracted n-tier architecture. My initial feeling is that we could create a "DomainMembershipProvider" which interacts with the domain model and then implement objects in the model which deal with the repository and handle validation/business logic. The repository would then implement data access using our (as-yet undecided) ORM/data access tool. Are there are any glaring holes in this approach - I haven't worked closely with the MembershipProvider class so may well be missing something. Alternatively, is there an approach that you think will better serve the requirements I described above? Thanks in advance for your thoughts and advice. Regards, Zac

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• Hibernate: order multiple one-to-many relations

  - by Markos Fragkakis

  I have a search screen, using JSF, JBoss Seam and Hibernate underneath. There are columns for A, B and C, where the relations are as follows: A (1< -- ) B (1< -- ) C A has a List< B and B has a List< C (both relations are one-to-many). The UI table supports ordering by any column (ASC or DESC), so I want the results of the query to be ordered. This is the reason I used Lists in the model. However, I got an exception that Hibernate cannot eagerly fetch multiple bags (it considers both lists to be bags). There is an interesting blog post here, and they identify the following solutions: Use @IndexColumn annotation (there is none in my DB, and what's more, I want the position of results to be determined by the ordering, not by an index column) Fetch lazily (for performance reasons, I need eager fetching) Change List to Set So, I changed the List to Set, which by the way is more correct, model-wise. First, if don't use @OrderBy, the PersistentSet returned by Hibernate wraps a HashSet, which has no ordering. Second, If I do use @OrderBy, the PersistentSet wraps a LinkedHashSet, which is what I would like, but the OrderBy property is hardcoded, so all other ordering I perform through the UI comes after it. I tried again with Sets, and used SortedSet (and its implementation, TreeSet), but I have some issues: I want ordering to take place in the DB, and not in-memory, which is what TreeSet does (either through a Comparator, or through the Comparable interface of the elements). Second, I found that there is the Hibernate annotation @Sort, which has a SortOrder.UNSORTED and you can also set a Comparator. I still haven't managed to make it compile, but I am still not convinced it is what I need. Any advice?

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• How do I detect if there is already a similar document stored in Lucene index.

  - by Jenea

  Hi. I need to exclude duplicates in my database. The problem is that duplicates are not considered exact match but rather similar documents. For this purpose I decided to use FuzzyQuery like follows: var fuzzyQuery = new global::Lucene.Net.Search.FuzzyQuery( new Term("text", queryText), 0.8f, 0); hits = _searcher.Search(query); The idea was to set the minimal similarity to 0.8 (that I think is high enough) so only similar documents will be found excluding those that are not sufficiently similar. To test this code I decided to see if it finds already existing document. To the variable queryText was assigned a value that is stored in the index. The code from above found nothing, in other words it doesn't detect even exact match. Index was build by this code: doc.Add(new global::Lucene.Net.Documents.Field( "text", text, global::Lucene.Net.Documents.Field.Store.YES, global::Lucene.Net.Documents.Field.Index.TOKENIZED, global::Lucene.Net.Documents.Field.TermVector.WITH_POSITIONS_OFFSETS)); I followed recomendations from bellow and the results are: TermQuery doesn't return any result. Query contructed with var _analyzer = new RussianAnalyzer(); var parser = new global::Lucene.Net.QueryParsers .QueryParser("text", _analyzer); var query = parser.Parse(queryText); var _searcher = new IndexSearcher (Settings.General.Default.LuceneIndexDirectoryPath); var hits = _searcher.Search(query); Returns several results with the maximum score the document that has exact match and other several documents that have similar content.

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• Codility-like sites for code golfs

  - by Adam Matan

  Hi, I've run into codility.com new cool service after listening to one of the recent stackoverflow.com podcasts. In short, it presents the user with a programming riddle to solve, within a given time frame. The user writes code in an online editor, and has the ability to run the program and view the standard output. After final submission, the user sees its final score and which tests failed him. Quoting Joel Spolsky: You are given a programming problem, you can do it in Java, C++, C#, C, Pascal, Python and PHP, which is pretty cool, and you have 30 minutes. And it gives you an editor in a webpage. And you've got to just start typing your code. And it's going to time you, basically you have to do it in a certain amount of time. And it actually runs your code and determines the performance characteristics of your code. It is intended for job interview screenings, but the idea seems very cool for code-golfs and for practicing new languages. Do you know if there's any proper open replacement? Adam

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• Cross-platform game development: ease of development vs security

  - by alcuadrado

  Hi, I'm a member and contributor of the Argentum Online (AO) community, the first MMORPG from Argentina, which is Free Software; which, although it's not 3D, it's really addictive and has some dozens of thousands of users. Really unluckily AO was developed in Visual Basic (yes, you can laugh) but the former community, so imagine, the code not only sucks, it has zero portability. I'm planning, with some friends to rewrite the client, and as a GNU/Linux frantic, want to do it cross-platform. Some other people is doing the same with the server in Java. So my biggest problem is that we would like to use a rapid development language (like Java, Ruby or Python) but the client would be pretty insecure. Ruby/Python version would have all it's code available, and the Java one would be easily decompilable (yes, we have some crackers in the community) We have consider the option to implement the security module in C/C++ as a dynamic library, but it can be replaced with a custom one, so it's not really secure. We are also considering the option of doing the core application in C++ and the GUI in Ruby/Python. But haven't analysed all it's implications yet. But we really don't want to code the entire game in C/C++ as it doesn't need that much performance (the game is played at 18fps on average) and we want to develop it as fast as possible. So what would you choose in my case? Thank you!

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• What programming languages do the top tier Universities teach?

  - by Simucal

  I'm constantly being inundated with articles and people talking about how most of today's Universities are nothing more than Java vocational schools churning out mediocre programmer after mediocre programmer. Our very own Joel Spolsky has his famous article, "The Perils of Java Schools." Similarly, Alan Kay, a famous Computer Scientist (and SO member) has said this in the past: "I fear — as far as I can tell — that most undergraduate degrees in computer science these days are basically Java vocational training." - Alan Kay (link) If the languages being taught by the schools are considered such a contributing factor to the quality of the school's program then I'm curious what languages do the "top-tier" computer science schools teach (MIT, Carnegie Mellon, Stanford, etc)? If the average school is performing so poorly due in large part the languages (or lack of) that they teach then what languages do the supposed "good" cs programs teach that differentiate them? If you can, provide the name of the school you attended, followed by a list of the languages they use throughout their coursework. Edit: Shog-9 asks why I don't get this information directly from the schools websites themselves. I would, but many schools websites don't discuss the languages they use in their class descriptions. Quite a few will say, "using high-level languages we will...", without elaborating on which languages they use. So, we should be able to get a pretty accurate list of languages taught at various well known institutions from the various SO members who have attended at them.

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• Load Images in WPF application

  - by LLS

  I am not familiar with WPF, and I just feel quite confusing. I am trying to create a little computer game, and there are elements I want to display dynamically. I use Image class and add the images to a canvas. But I'm not sure whether it's a good practice. I feel that adding controls to canvas seem to be a little wired. And I'm a little concerned about the performance, because I may need many images. The real problem is, I can't load the images from the image files. I see an example in a text book like this (XMAL): <Image Panel.ZIndex="0" Margin="0,0,0,0" Name ="image1"> <Image.Source> <BitmapImage UriSource="Bell.gif" /> </Image.Source> </Image> Where Bell.gif is added into the project. And I tried to copy this in code to create an image. new Image { Source = new BitmapImage(new Uri("Blockade.bmp"))} But I got invalid Uri exception. After some search in the Internet, I found that loading resources dynamically seems to be difficult. Can I load the files added to the project dynamically? If I use absolute path then it's OK. But I can't expect every computer will put the files in the same location. Can I use relative path? I tried new Image { Source = new BitmapImage(new Uri(@"Pictures\Blank Land.bmp", UriKind.Relative)) } But it doesn't work. (The image is blank) Thanks.

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• ai: Determining what tests to run to get most useful data

  - by Sai Emrys

  This is for http://cssfingerprint.com I have a system (see about page on site for details) where: I need to output a ranked list, with confidences, of categories that match a particular feature vector the binary feature vectors are a list of site IDs & whether this session detected a hit feature vectors are, for a given categorization, somewhat noisy (sites will decay out of history, and people will visit sites they don't normally visit) categories are a large, non-closed set (user IDs) my total feature space is approximately 50 million items (URLs) for any given test, I can only query approx. 0.2% of that space I can only make the decision of what to query, based on results so far, ~10-30 times, and must do so in <~100ms (though I can take much longer to do post-processing, relevant aggregation, etc) getting the AI's probability ranking of categories based on results so far is mildly expensive; ideally the decision will depend mostly on a few cheap sql queries I have training data that can say authoritatively that any two feature vectors are the same category but not that they are different (people sometimes forget their codes and use new ones, thereby making a new user id) I need an algorithm to determine what features (sites) are most likely to have a high ROI to query (i.e. to better discriminate between plausible-so-far categories [users], and to increase certainty that it's any given one). This needs to take into balance exploitation (test based on prior test data) and exploration (test stuff that's not been tested enough to find out how it performs). There's another question that deals with a priori ranking; this one is specifically about a posteriori ranking based on results gathered so far. Right now, I have little enough data that I can just always test everything that anyone else has ever gotten a hit for, but eventually that won't be the case, at which point this problem will need to be solved. I imagine that this is a fairly standard problem in AI - having a cheap heuristic for what expensive queries to make - but it wasn't covered in my AI class, so I don't actually know whether there's a standard answer. So, relevant reading that's not too math-heavy would be helpful, as well as suggestions for particular algorithms. What's a good way to approach this problem?

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• How can I coordinate code review tool and RCS (specifically git)

  - by Chris Nelson

  We're committed to git for code management. We're trying to find a tool that will help us systematize code reviews. We're considering Gerrit and Code Collaborator but would welcome other suggestions. We're having a problem answering the question, "How do we know every commit was reviewed?" (Or "What commits have yet to be reviewed?") One answer would be to submit every commit or every push for review and track incomplete reviews in the review tool. I'm not entirely happy with relying on a another tool -- especially if it's not open source -- to tell us this. What seems to be a better answer is to rely on sign offs in git (e.g., "Signed-off-by: Chris Nelson") and use a hook in the review tool to sign off commits on behalf of the reviewer. And advantage of this is if we use some other review mechanism for some commits, we have just one place to look for results. One problem with this is that we can't require review before push because the review tool is unlikely to have access to the developer's private repository clone to add the sign-off. Any ideas on integrating code review with code management to achieve ease of use and high visibility of unreviewed changes?

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• Sending Email through Gmail

  - by persistence

  I am writing a program that send an email through GMail but I have serious Operation timeout error. What is the likely cause. class Mailer { MailMessage ms; SmtpClient Sc; public Mailer() { Sc = new SmtpClient("smtp.gmail.com"); //Sc.Credentials = CredentialCache.DefaultNetworkCredentials; Sc.EnableSsl = true; Sc.Port =465; Sc.Timeout = 900000000; Sc.DeliveryMethod = SmtpDeliveryMethod.Network; Sc.UseDefaultCredentials = false; Sc.Credentials = new NetworkCredential("uid", "mypss"); } public void MailTodaysBirthdays(List<Celebrant> TodaysCelebrant) { int i = TodaysCelebrant.Count(); foreach (Celebrant cs in TodaysCelebrant) { //if (IsEmail(cs.EmailAddress.ToString().Trim())) //{ ms = new MailMessage(); ms.To.Add(cs.EmailAddress); ms.From = new MailAddress("uid","Developers",System.Text.Encoding.UTF8); ms.Subject = "Happy Birthday "; String EmailBody = "Happy Birthday " + cs.FirstName; ms.Body = EmailBody; ms.Priority = MailPriority.High; try { Sc.Send(ms); } catch (Exception ex) { Sc.Send(ms); BirthdayServices.LogEvent(ex.Message.ToString(),EventLogEntryType.Error); } //} } } }

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• How Random is System.Guid.NewGuid()? (Take two)

  - by Vilx-

  Before you start marking this as a duplicate, read me out. The other question has a (most likely) incorrect accepted answer. I do not know how .NET generates its GUIDs, probably only Microsoft does, but there's a high chance it simply calls CoCreateGuid(). That function however is documented to be calling UuidCreate(). And the algorithms for creating an UUID are pretty well documented. Long story short, be as it may, it seems that System.Guid.NewGuid() indeed uses version 4 UUID generation algorithm, because all the GUIDs it generates matches the criteria (see for yourself, I tried a couple million GUIDs, they all matched). In other words, these GUIDs are almost random, except for a few known bits. This then again raises the question - how random IS this random? As every good little programmer knows, a pseudo-random number algorithm is only as random as its seed (aka entropy). So what is the seed for UuidCreate()? How ofter is the PRNG re-seeded? Is it cryptographically strong, or can I expect the same GUIDs to start pouring out if two computers accidentally call System.Guid.NewGuid() at the same time? And can the state of the PRNG be guessed if sufficiently many sequentially generated GUIDs are gathered?

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• Python: How to execute a SQL file or command

  - by Mestika

  Hi, I have this Python script: import sys import getopt import timeit import random import os import re import ibm_db import time from string import maketrans runs=5 queries=50 file = open("results.txt", "a") for r in range(5): print "Run %s\n" % r os.system("python reads.py -r1 -pquery1.sql -q50 -sespec") file.write('END QUERY READ 01') file.close() os.system("python query_read_02.py") Everything here is working, it is creating the results.txt file, it run the os.system("python reads.py...") file and that file is doing everything it's suppose to, but the problem comes when go and run the query_read_02.py file. In this file, it should execute a SQL command or a SQL file on my database, so I can create an index and see what the performance of that input is, but how do i do it? I create the connection to the database in the reads.py file, but it's hard to create the queries in there because I doesn't keep track of which file it has reached, it just execute commands from what the parameters are. I hope I've explained myself clear enough, otherwise please let me know. I just want to execute a SQL command or file which each query_read_0x.py file. Sincerely Mestika

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• Why not systematically attach event in WPF instead of using delegate ?

  - by user310291

  For a button to handle event, we can add a delegate to the click property of the button: this.button1.Click += new System.EventHandler(this.button1_Click); But in WPF contrary to Winform, you can also attach a handler http://msdn.microsoft.com/en-us/magazine/cc785480.aspx So why not do so for the button ? Is performance better in first case maybe ? Update: I mean this Attached Events In order to enable elements to handle events that are declared in a different element, WPF supports something called attached events. Attached events are routed events that support a hookup in XAML on elements other than the type on which the event is declared. For example, if you want the Grid element to listen for a Button.Click event to bubble past, you would simply hook it up like the following: <Grid Button.Click="myButton_Click"> <Button Name="myButton" >Click Me</Button> </Grid> The resulting code in the compile-time-generated partial class now looks like this: #line 5 "..\..\Window1.xaml" ((System.Windows.Controls.Grid)(target)).AddHandler( System.Windows.Controls.Primitives.ButtonBase.ClickEvent, new System.Windows.RoutedEventHandler(this.myButton_Click));

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• SQLite on iPhone - Techniques for tracking down multithreading-related bugs

  - by Jasarien

  Hey guys, I'm working with an Objective-C wrapper around SQLite that I didn't write, and documentation is sparse... It's not FMDB. The people writing this wrapper weren't aware of FMDB when writing this code. It seems that the code is suffering from a bug where database connections are being accessed from multiple threads -- which according to the SQLite documentation won't work if the if SQLite is compiled with SQLITE_THREADSAFE 2. I have tested the libsqlite3.dylib provided as part of the iPhone SDK and seen that it is compiled in this manner, using the sqlite_threadsafe() routine. Using the provided sqlite library, the code regularly hits SQLITE_BUSY and SQLITE_LOCKED return codes when performing routines. To combat this, I added some code to wait a couple of milliseconds and try again, with a maximum retry count of 50. The code didn't contain any retry logic prior to this. Now when a sqlite call returns SQLITE_BUSY or SQLITE_LOCKED, the retry loop is invoked and the retry returns SQLITE_MISUSE. Not good. Grasping at straws, I replaced the provided sqlite library with a version compiled by myself setting SQLITE_THREADSAFE to 1 - which according to the documentation means sqlite is safe to be used in a multithreaded environment, effectively serialising all of the operations. It incurs a performance hit, that which I haven't measured, but it ridded the app of the SQLITE_MISUSE happening and seemed to not need the retry logic as it never hit a busy or locked state. What I would rather do is fix the problem of accessing a single db connection from multiple threads, but I can't for the life of me find where it's occurring. So if anyone has any tips on locating multithreaded bugs I would be extremely appreciative. Thanks in advance.

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• What file format can represent an uncompressed raster image at 48 or 64 bits per pixel?

  - by finnw

  I am creating screenshots under Windows and using the LockBits function from GDI+ to extract the pixel data, which will then be written to a file. To maximise performance I am also: Using the same PixelFormat as the source bitmap, to avoid format conversion Using the ImageLockModeUserInputBuf flag to extract the pixel data into a pre-allocated buffer This pre-allocated buffer (pointed to by BitmapData::Scan0) is part of a memory-mapped file (to avoid copying the pixel data again.) I will also be writing the code that reads the file, so I can use (or invent) any format I wish. However I would prefer to use a well-known format that existing programs (ideally web browsers) are able to read, because that means I can visually confirm that the images are correct before writing the code for the other program (that reads the image.) I have implemented this successfully for the PixelFormat32bppRGB format, which matches the format of a 32bpp BMP file, so if I extract the pixel data directly into the memory-mapped BMP file and prefix it with a BMP header I get a valid BMP image file that can be opened in Paint and most browsers. Unfortunately one of the machines I am testing on returns pixels in PixelFormat64bppPARGB format (presumably this is influenced by the video adapter driver) and there is no corresponding BMP pixel format for this. Converting to a 16, 24 or 32bpp BMP format slows the program down considerably (as well as being lossy) so I am looking for a file format that can use this pixel format without conversion, so I can extract directly into the memory-mapped file as I have done with the 32bpp format. What raster image file formats support 48bpp and/or 64bpp?

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• Should I store generated code in source control

  - by Ron Harlev

  This is a debate I'm taking a part in. I would like to get more opinions and points of view. We have some classes that are generated in build time to handle DB operations (in This specific case, with SubSonic, but I don't think it is very important for the question). The generation is set as a pre-build step in Visual Studio. So every time a developer (or the official build process) runs a build, these classes are generated, and then compiled into the project. Now some people are claiming, that having these classes saved in source control could cause confusion, in case the code you get, doesn't match what would have been generated in your own environment. I would like to have a way to trace back the history of the code, even if it is usually treated as a black box. Any arguments or counter arguments? UPDATE: I asked this question since I really believed there is one definitive answer. Looking at all the responses, I could say with high level of certainty, that there is no such answer. The decision should be made based on more than one parameter. Reading the answers below could provide a very good guideline to the types of questions you should be asking yourself when having to decide on this issue. I won't select an accepted answer at this point for the reasons mentioned above.

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• Need help in support multiple resolution screen on android

  - by michael

  Hi, In my android application, I would like to support multiple screens. So I have my layout xml files in res/layout (the layout are the same across different screen resolution). And I place my high-resolution asserts in res/drawable-hdpi In my layout xml, I have <?xml version="1.0" encoding="utf-8"?> <TableLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/table" android:background="@drawable/bkg"> And I have put bkg.png in res/drawable-hdpi And I have started my emulator with WVGA-800 as avd. But my application crashes: E/AndroidRuntime( 347): Caused by: android.content.res.Resources$NotFoundException: Resource is not a Drawable (color or path): TypedValue{t=0x1/d=0x7f020023 a=-1 r=0x7f020023} E/AndroidRuntime( 347): at android.content.res.Resources.loadDrawable(Resources.java:1677) E/AndroidRuntime( 347): at android.content.res.TypedArray.getDrawable(TypedArray.java:548) E/AndroidRuntime( 347): at android.view.View.<init>(View.java:1850) E/AndroidRuntime( 347): at android.view.View.<init>(View.java:1799) E/AndroidRuntime( 347): at android.view.ViewGroup.<init>(ViewGroup.java:284) E/AndroidRuntime( 347): at android.widget.LinearLayout.<init>(LinearLayout.java:92) E/AndroidRuntime( 347): ... 42 more Does anyone know how to fix my problem? Thank you.

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• How to properly combine two files in XAML in Microsoft Blend?

  - by MartyIX

  Hello, I have a test project with the file MainWindow.xaml with the content: <Window x:Class="MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:ad="clr-namespace:AvalonDock;assembly=AvalonDock" xmlns:diag="clr-namespace:System.Diagnostics;assembly=WindowsBase" xmlns:view="clr-namespace:Sokoban.View;assembly=Solvers" Title="Window1" Height="300" Width="300" Loaded="Window_Loaded"> <ad:DockingManager x:Name="dockingManager"> <ad:ResizingPanel Orientation="Vertical"> <view:Solvers x:Name="solvers" diag:PresentationTraceSources.TraceLevel="High" /> <!-- LINE BELOW DEMONSTRATES WORKING CODE INSTEAD OF LINE ABOVE --> <!--<ad:DocumentPane Name="GamesDocumentPane" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"> <ad:DockableContent x:Name="classesContent" Title="Classes"> <TextBlock>test</TextBlock> </ad:DockableContent> </ad:DocumentPane>--> </ad:ResizingPanel> </ad:DockingManager> </Window> and in another project I have the file Solvers.xaml: <ad:DocumentPane x:Class="Sokoban.View.Solvers" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:ad="clr-namespace:AvalonDock;assembly=AvalonDock" xmlns:diag="clr-namespace:System.Diagnostics;assembly=WindowsBase" Name="GamesDocumentPane" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"> </ad:DocumentPane> When I open my Visual Studio solution in Microsoft Blend 4 then I see the error: InvalidOperationException: DocumentPane must be put under a DockingManager! when I open either MainWindow.xaml or Solvers.xaml. It is all right in Solvers.xaml because there really is no DockingManager but MainWindow.xaml should work, shouldn't it? How to solve the problem? Note: It seems to me that the files are processed separately and because the file Solvers.xaml contains the error the MainWindow.xaml file also contains the very same error. Note 2: XAML files use AvalonDock library Is there a way how to say that Solvers.xaml is only an extension of another file? Thank you for any help!

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