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  • Which coding style is more common?

    - by Babiker
    In no way shape or form am i advertising/promoting my programming style, but as far as 'multiple variable declarations' are concerned, which case is more acceptable professionally and commonly: case 1: private $databaseURL = "localhost" ; private $databaseUName = "root" ; private $databasePWord = "" ; private $databaseName = "AirAlliance"; case 2: private $databaseURL = "localhost"; private $databaseUName = "root"; private $databasePWord = ""; private $databaseName = "AirAlliance"; The reason i like case 1 is because i can skim though it and see that all is correct way faster than case 2. Also i can visually get familiar with variable names witch makes it faster to work with them l latter on the program.

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  • Problem with the nonresponding threads

    - by Oxygen
    Hello there, I have a web application which runs multiple threads on button click each thread making IO call on different ipAddresses ie(login windows account and then making file operations). There is a treshold value of 30 seconds. I assume that while login attempt if the treshold is exceeded, device on ipAddress does not match my conditions thus I dont care it. Thread.Abort() does not fit my situation where it waits for the IO call to finish which might take long time. I tried doing the db operations acording to states of the threads right after the treshold timeout. It worked fine but when I checked out the log file, I noticed that the thread.IsAlive property of the nonresponding threads were still true. After several debuggings on my local pc, I encountered a possible deadlock situation (which i suspect) that my pc crashed badly. In short, do you have any idea about killing (forcefully) nonresponding threads (waiting for the IO opreation) right after the execution of the button_click? (PS: I am not using the threadpool) Oguzhan

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  • Sporadic name resolution failure happening on web service call

    - by ansleygal
    One of our wcf service applications calls a seperate third party web service to submit information. We are getting the following error every so often, but not all the time: System.Net.WebException: The remote name could not be resolved: 'ws.examplesite.net' at System.Net.HttpWebRequest.GetRequestStream() at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters) The wierd thing is that after the error happens, we can hit "Submit" again a second later and it will go through just fine. We have checked and double checked with our network guys and they have confirmed that DNS is correct, and they have done multiple nslookups in a row to confirm. This is happening in all environments (dev, test and prod). We use the third party test and prod urls, and it is happening when we point to both. Does anyone have any other trouble shooting techniques for this or any reason this would happen? Much thanks, ~Ansley

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  • Programmaticaly prevent Vista desktop search (WDS) from indexing pst files placed on mapped network

    - by Jao
    Hi! After several days and multiple attempts I didn't find any 100% solution for this trouble. My search and investigation scopes: Direct access to registry: HKLM\SOFTWARE\Microsoft\Windows Search\CrawlScopeManager\Windows\SystemIndex\WorkingSetRules HKCU\Software\Microsoft\Windows Search\Gather\Windows\SystemIndex\Protocols\Mapi HKLM\SOFTWARE\Microsoft\Windows Search\Gather\Windows\SystemIndex\Sites\ and other keys... Windows Search 3.X interfaces like ISearchManager using Microsoft.Search.Interop Microsoft.Office.Interop.Outlook classes: NameSpace, Store AD policies (useless, no effect :( Preferred technologies: VB.NET, C#. This solution must be deployed within a large organization (about 5000 wokstations). Any ideas? Thanks in advance.

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  • C++ Preprocessor string literal concatenation

    - by ezpz
    I found this regarding how the C preprocessor should handle string literal concatenation (phase 6). However, I can not find anything regarding how this is handled in C++ (does C++ use the C preprocessor?). The reason I ask is that I have the following: const char * Foo::encoding = "\0" "1234567890\0abcdefg"; where encoding is a static member of class Foo. Without the availability of concatenation I wouldnt be able to write that sequence of characters like that. const char * Foo::encoding = "\01234567890\0abcdefg"; Is something entirely different due to the way \012 is interpreted. I dont have access to multiple platforms and I'm curious how confident I should be that the above is always handled correctly - i.e. I will always get { 0, '1', '2', '3', ... }

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  • ISO Files to USB &ndash; The Cheap and Easy Way

    - by RonGarlit
    (DISCLAIMER: Yes there are lots of more elegant ISO software beside the free Microsoft one I’m about to show. But free is free and it has been tested and works for me for making advance bootable USB drives. That is another story. Look up Windows 8 Developer Preview for that one on BING.) For those of use that work with new technology all the time we accumulate a lot of ISO files and have to burn them to CD/DVD’s quite often. But we now have machines without burner in the corporate environment. We have personally Netbooks and light wait highly mobile laptops that do not have DVD burner. USB ports are all the rage and now we have USB 3.0 which is way faster than the 2.0 we are used to. Just looking at the technology, space saving and the cost issues alone is a reason to buy these answer to the DVD’s. So what is special about USB 2.0 and USB 3.0? USB 2 has a maximum speed of 480 Mbps... (That is Megabits per SECOND!!) Now look at the storage that we have with USB thumb drives that are now up to 64 GB in size, cell phone and PDAs that have a lots of internal storage built in well above the 16 Gig range. At the MAX USB 2.0 speed of 480 Mbps a full transfer of data in between devices can take a long time. Time is money right. Every back up a iPhone? Don’t get me started. So at least the engineers have been planning ahead with USB 3.0 which offers a maximum transfer speed of 4.8 Gbps... (That is Giga bits per SECOND!!) That speed is almost 10 times faster than USB 2.0 …. We don’t need to do the math on that one do we? But for now I'm thrilled with USB 2.0 and the fact I can get these little 4 Gig USB drives for $4.00 each at Staples on sale. Well that is a no brainer don’t you think. But what can you do with them to replace that DVD. Simply and cheaply put………. THIS! First let’s get an ISO file like the Visual Studio 2010 Ultimate DVD ISO from MSDN to demonstrate with. I develop on several computers so this is a good choice for me. So we downloaded the ISO file and put it in a folder somewhere like this. Next we go download to the Windows 7 USB/DVD Download Tool site and read about the tool. http://www.microsoftstore.com/store/msstore/html/pbPage.Help_Win7_usbdvd_dwnTool And click this like to get the tool and install it. Once it is installed you go to the Start, Programs menu, Windows 7 USB DVD Download Tool folder. And then click the tool to open it up. As you will see it is a sweet, simple tool that was originally designed to put the ISO for Windows 7 which is designed to be bootable on a USB or DVD for us geeks to play with. It is now being used for the Windows 8 Developer Preview by many developers for that for the same purpose it was built for in the past. But for now we will use it to put a NON Bootable ISO on a USB. Hey it does the job and I’m reusing a left over program. Why buy the fancy one or a free trial and clutter up my machine. We will click the BROWSE button and navigate to where we put our ISO file we want to put on the USB drive. Obviously we are going to click NEXT and continue to select a USB Device (you can guess what the DVD button is for). Next we select the USB that we have plugged into one of our laptops USB ports. Then we click the BEGIN COPYING button and the first thing the program does is format our USB drive. Then it starts copying out files out of the ISO and constructing the USB as if it was a DVD. So now that the files are copying to the drive I’m going to warn you. We will error out here. This program was design for bootable ISO’s of which this one is NOT. No problem because what fails it the writing of the bootable data to the drive that isn’t there. No biggie…. Forget the STARTOVER button is even there and click the dialog’s CLOSE button and exit the program. Now go to Windows Explorer and navigate to the USB Device. You can now access everything and even add stuff to the drive. But for me I want to keep this drive for one purpose and that is to install VS2010 on various machines. So the only stuff I’ll add to this is a folder of notes on things on visual studio that I might want to put on other machines I’m installing VS2010 on to. So that is it. Have a nice day! The Ron

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  • SSRS 2005: Filter Nested Table within a List

    - by Even Mien
    In SQL Server Reporting Services 2005, how can I filter a nested table within a list? I have 2 datasets. The first, datasetHeader, contains one row per account. The second, datasetDetails contains multiple rows per account. Control: Dataset name List: datasetHeader Table: datasetDetails The table is placed within the list. When I attempt to filter on the table, I get fields from datasetHeader instead of datasetDetails. Previously I had the table within a subreport, and I had that working by using parameters; however, I needed to pull it into the main report because of the implied KeepTogether=true property for subreports that was causing undesired pagination.

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  • Design for a machine learning artificial intelligence framework (community wiki)

    - by Lirik
    This is a community wiki which aims to provide a good design for a machine learning/artificial intelligence framework (ML/AI framework). Please contribute to the design of a language-agnostic framework which would allow multiple ML/AI algorithms to be plugged into a single framework which: runs the algorithms with a user-specified data set. facilitates learning, qualification, and classification. allows users to easily plug in new algorithms. can aggregate or create an ensemble of the existing algorithms. can save/load the progress of the algorithm (i.e. save the network and weights of a neural network, save the tree of a decision tree, etc.). What is a good design for this sort of ML/AI framework?

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  • CakePHP: shortcomings with indirectly associated models

    - by Dan
    I'm having some issues with dealing with indirectly associated models in cakephp. My current model setup is as follows: Deliveries hasOne License License belongsTo Delivery License hasAndBelongsToMany Product (and vice-versa) License hasAndBelongsToMany ProductOption (and vice-versa) I'm trying to save information about ALL of these models inside ONE form. The shortcomings I'm running into are the following: The form helper only seems able to see the field type one level deep. saveAll() only seems able to save records one level deep (for multiple model forms). I'm searching everywhere for the solutions to these issues, but since I'm new to CakePHP, I'm not sure what the newest methods or "correct" methods are for dealing with these issues. Any advice is much appreciated. Thank you all! EDIT: I've posted code to my failed attempt here: http://bin.cakephp.org/saved/58501

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  • Segue Popover won't behave properly

    - by CStreel
    I'm trying to use Segue to present then dismiss a Popover view a UIBarButtonItem is clicked. I've created a generic Segue that is not anchored to anything but the view and given it a name I've Anchored the UIBarButtonItem in the Interface Builder to: - (IBAction)clickedSettings:(id)sender { if(self.popSegue != nil) { [self.popSegue.popoverController dismissPopoverAnimated:YES]; } else { //Current says only a button may [self performSegueWithIdentifier:@"Settings" sender:sender]; } } But when ever i click the button to display the Segue it gives me an error: Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'UIStoryboardPopoverSegue must be presented from a bar button item or a view.' It doesn't even hit my -(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender I've read the following questions on stack: iOS:How to dismiss Popover UIBarButtonItem + popover segue creates multiple popovers But i still get the same error. For the life of me i can't figure out what is going wrong

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  • SQL CLR Assembly Error 80131051 when late binding to a registered C# COM .dll

    - by Shanubus
    I must have hit an unusual one, because I can't find any reference to this specific failing anywhere... Scenario: I have a legacy SQL function used to transform(encrypt) data. This function is called from within many stored procedures used by multiple applications. I say this, because the obvious answer of 'just call it from your code' is not really an option (or at least one I'd prefer not explore). The legacy function used sp_OA with an ActiveX dll on SQL2000 to perform its work. The new function is targeted at SQL2008 x64. I am ditching the sp_OA call in favor of CLR assembly; and am getting rid of the ActiveX dll and using a COM+ .dll (3rd party) to perform the same work. This 3rd party COM+ is required to be used based on spec given to me, so can't get rid of this piece either. Problem: After multiple attempts at getting this to work I have eliminated the following approaches 1) Create a Sql Assembly to call the local COM+ directly -- Can't do this as it requires a reference to System.EnterpriseServices. Including this requires that a whole slew of unsupported assemblies be registered which I don't want. The COM+ requires it's methods to be accessed via an Interface, so my attempts at late binding to it directly have not been successful (late binding would allow me to drop the unsupported references). 2) Create a Sql Assembly which references a C# class library that then calls the COM+. -- Same issue as #1; since the referenced dll uses System.EnterpriseServices and will be added as a dependency when referenced in the Sql Assembly, again trying to load all the unsupported libraries 3) Create a Sql Assembly which late binds to an ActiveX COM dll that calls the COM+. -- Worked in my dev environment, but can't go to x64 in production with ActiveX dll's written in VB6 (not to mention I hate backtracking anyway)... again failure... I am now onto an approach that is almost working, with of course one last hangup. I now have -a Sql Assembly that late binds to a C# COM dll, eliminating the need for including System.EnterpriseServices and eliminating the need to reference the C# COM in the SqlAssembly itself. The C# COM does reference System.EnterpriseServices to call the COM+, but since I am late binding to it from the SqlAssembly, I bypass the need for Sql to actually load them as referenced assemblies. Works in debugger.. Works on my dev box when the SqlAssembly dll is referenced in a test console app and called directly Installs to Sql2008 just fine Executing the actual UDF works, but returns no data due to a failure reporting from the late bound dll! So the SqlAssembly is instanciated just fine. It actually fails on it's late binding to the C# COM, which is working from a test console app on the same machine. It appears to be a difference in behavior based on whether called from within the SQL UDF or not. Since it is working on the same box from my console app, I am assuming it's on the SQL side. My steps to install were. --Install the COM+ dll and ensure it can be called successfully (as from with in the console app) --Register the C# COM dll (which calls the COM+) and get it to the GAC (again proofed to be working from console app) --Create my Assymetric Key CREATE ASYMMETRIC KEY SqlCryptoKey FROM EXECUTABLE FILE = 'D:\SqlEx.dll' CREATE LOGIN SqlExLogin FROM ASYMMETRIC KEY SqlExKey GRANT UNSAFE ASSEMBLY TO SqlExLogin GO --Add the assembly CREATE ASSEMBLY SqlEx FROM 'D:\SqlEx.dll' WITH PERMISSION_SET = UNSAFE; GO --Create the function CREATE FUNCTION dbo.f_SqlEx( @clearText [nvarchar](512) ) RETURNS nvarchar(512) WITH EXECUTE AS CALLER AS EXTERNAL NAME SqlEx.[SqlEx.SqlEx].Ex GO With all that done, I can now call my function SELECT dbo.f_SqlEx('test') But get this error in the event log... Retrieving the COM class factory for component with CLSID {F69D6320-5884-323F-936A-7657946604BE} failed due to the following error: 80131051. I can't really provide direct code examples, due to internal security implications; but all the code itself seems to work, I am suspecting perms or something of the like... I just find it odd that I can't find any reference to error 80131051. If someone out there believe some 'indirect' code samples will help, I will be happy to provide. Any assistance is appreciated.

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  • SQLCEException was unhandled: Internal Error: Cannot open the shared memory region

    - by dwaz
    I am trying to do a TableAdapter.Fill(dataTable) and it fails with the above error. Here is the code in Zenware.DataSet.Designer.cs [global::System.Diagnostics.DebuggerNonUserCodeAttribute()] [global::System.ComponentModel.DataObjectMethodAttribute(global::System.ComponentModel.DataObjectMethodType.Fill, true)] public virtual int Fill(ZenwareDataSet.BatchPDADataTable dataTable) { this.Adapter.SelectCommand = this.CommandCollection[0]; if ((this.ClearBeforeFill == true)) { dataTable.Clear(); } int returnValue = this.Adapter.Fill(dataTable); // <---Fails here. return returnValue; } This is generated code. Maybe there is something that I need to change? I am wondering if my app has multiple connections to the database. What can this be? Thanks for any help you can provide. Windows Mobile 6.1 device (Trimble Juno SB) SQLServerCompact 3.5 Service Pack 2 Microsoft .NET CF 3.5

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  • Additional spaces in String having read text file to String using FileInputStream

    - by David
    Hi, I'm trying to read in a text file to a String variable. The text file has multiple lines. Having printed the String to test the "read-in" code, there is an additional space between every character. As I am using the String to generate character bigrams, the spaces are making the sample text useless. The code is try{ FileInputStream fstream = new FileInputStream(textfile); DataInputStream in = new DataInputStream(fstream); BufferedReader br = new BufferedReader(new InputStreamReader(in)); //Read corpus file line-by-line, concatenating each line to the String "corpus" while ((strLine = br.readLine()) != null) { corpus = (corpus.concat(strLine)); } in.close(); //Close the input stream } catch (Exception e) {//Catch exception if any System.err.println("Error test check: " + e.getMessage()); } I'd be grateful for any advice. Thanks.

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  • How to use Blazeds with a custom classloader?

    - by festerwim
    Hi, has anybody tried using a custom classloader with BlazeDS? We have a web application using BlazeDS and we can convert Java objects in to ActionScript object and back without problems in the main application. However, we also have a plug-in mechanism based on a custom classloader. BlazeDS cannot map the types contained in jar files of that custom classloader since I don't know how to tell it to BlazeDS. Has anybody already done this? The livedocs of TypeMarshallingcontext show a setClassloader() method, but since the context seems to be a singleton, I assume this will not work if you have multiple custom classloaders (we have 1 for each plugin that is deployed) regards, Wim

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  • underline text in UIlabel

    - by semix
    How to underline a text that could be multiple lines of string? I find some people suggest UIWebView, but it is obviously too heave a class for just text rendering. My thoughts was to figure out the start point and length of each string in each line. And draw a line under it accordingly. I meet problems at how to figure out the length and start point forthe string. Can anybody help me on this? I try to use UILable::textRectForBounds, this should be the drawing bounding rect for the text right? Then I have to work on the aligment ? How can I get the start point of each line when it is center-justified and right justfied? I am new here, so thank in advance.

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  • Any alternative to Sybase Sql Advantage?

    - by eKek0
    Sybase Sql Advantage is the default editor for the Sybase database. But it has lots of shortcomings, because it basically is what Notepad is for Windows users: Can't do multiple undo's Monochrome, text is black and background is white Can't see what character did you exactly paste from clipboard, and sometimes this lead to weirdness behaviour Don't see what line or column you are in the moment Lack of funcionality like exports to different formats, integration with source control, plugins, etc. I have to deal with this editor in my daily work, so I was wondering if there are any other tool. Do you know any replacement?

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  • SWT applet: swt-win32-3650.dll already loaded in another classloader

    - by kilonet
    I have multiple pages with java applet written with SWT. The problem is, applet loads only on first page, to load it on another page i need restart browser, otherwise i get following error: Exception in thread "Thread-27" java.lang.UnsatisfiedLinkError: Could not load SWT library. Reasons: no swt-win32-3650 in java.library.path no swt-win32 in java.library.path Native Library C:\Documents and Settings\xxx\Local Settings\Temp\swtlib-32\swt-win32-3650.dll already loaded in another classloader C:\Documents and Settings\xxx\Local Settings\Temp\swtlib-32\swt-win32.dll: %1 is not a valid Win32 application at org.eclipse.swt.internal.Library.loadLibrary(Unknown Source) at org.eclipse.swt.internal.Library.loadLibrary(Unknown Source) at org.eclipse.swt.internal.C.<clinit>(Unknown Source) at org.eclipse.swt.widgets.Display.<clinit>(Unknown Source) I wonder, how can I unload swt dlls when browser page with applet is closed?

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  • Windows Phone 7 development: first impressions

    - by DigiMortal
    After hard week in work I got some free time to play with Windows Phone 7 CTP developer tools. Although my first test application is still unfinished I think it is good moment to share my first experiences to you. In this posting I will give you quick overview of Windows Phone 7 developer tools from developer perspective. If you are familiar with Visual Studio 2010 then you will feel comfortable because Windows Phone 7 CTP developer tools base on Visual Studio 2010 Express. Project templates There are five project templates available. Three of them are based on Silverlight and two on XNA Game Studio: Windows Phone Application (Silverlight) Windows Phone List Application (Silverlight) Windows Phone Class Library (Silverlight) Windows Phone Game (XNA Game Studio) Windows Phone Game Library (XNA Game Studio) Currently I am writing to test applications. One of them is based on Windows Phone Application and the other on Windows Phone List Application project template. After creating these projects you see the following views in Visual Studio. Windows Phone Application. Click on image to enlarge. Windows Phone List Application. Click on image to enlarge.  I suggest you to use some of these templates to get started more easily. Windows Phone 7 emulator You can run your Windows Phone 7 applications on Windows Phone 7 emulator that comes with developer tools CTP. If you run your application then emulator is started automatically and you can try out how your application works in phone-like emulator. You can see screenshot of emulator on right. Currently there is opened Windows Phone List Application as it is created by default. Click on image to enlarge it. Emulator is a little bit slow and uncomfortable but it works pretty well. This far I have caused only couple of crashes during my experiments. In these cases emulator works but Visual Studio gets stuck because it cannot communicate with emulator. One important note. Emulator is based on virtual machine although you can see only phone screen and options toolbar. If you want to run emulator you must close all virtual machines running on your machine and run Visual Studio 2010 as administrator. Once you run emulator you can keep it open because you can stop your application in Visual Studio, modify, compile and re-deploy it without restarting emulator. Designing user interfaces You can design user interface of your application in Visual Studio. When you open XAML-files it is displayed in window with two panels. Left panel shows you device screen and works as visual design environment while right panel shows you XAML mark-up and let’s you modify XML if you need it. As it is one of my very first Silverlight applications I felt more comfortable with XAML editor because property names in property boxes of visual designer confused me a little bit. Designer panel is not very good because it is visually hard to follow. It has black background that makes dark borders of controls very hard to see. If you have monitor with very high contrast then it is may be not a real problem. I have usual monitor and I have problem. :) Putting controls on design surface, dragging and resizing them is also pretty painful. Some controls are drawn correctly but for some controls you have to set width and height in XML so they can be resized. After some practicing it is not so annoying anymore. On the right you can see toolbox with some controllers. This is all you get out of the box. But it is sufficient to get started. After getting some experiences you can create your own controls or use existing ones from other vendors or developers. If it is your first time to do stuff with Silverlight then keep Google open – you need it hard. After getting over the first shock you get the point very quickly and start developing at normal speed. :) Writing source code Writing source code is the most familiar part of this action. Good old Visual Studio code editor with all nice features it has. But here you get also some surprises: The anatomy of Silverlight controls is a little bit different than the one of user controls in web and forms projects. Windows Phone 7 doesn’t run on full version of Windows (I bet it is some version of Windows CE or something like this) then there is less system classes you can use. Some familiar classes have less methods that in full version of .NET Framework and in these cases you have to write all the code by yourself or find libraries or source code from somewhere. These problems are really not so much problems than limitations and you get easily over them. Conclusion Windows Phone 7 CTP developer tools help you do a lot of things on Windows Phone 7. Although I expected better performance from tools I think that current performance is not a problem. This far my first test project is going very well and Google has answer for almost every question. Windows Phone 7 is mobile device and therefore it has less hardware resources than desktop computers. This is why toolset is so limited. The more you need memory the more slower is device and as you may guess it needs the more battery. If you are writing apps for mobile devices then make your best to get your application use as few resources as possible and act as fast as possible.

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  • Android vertical line xml

    - by Kaspa
    Hello, I'm trying to figure out how to define a verical line (1px thick) to be used as a drawable. to make a horizontal one, it's pretty straightforward: <shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="line"> <stroke android:width="1dp" android:color="#0000FF"/> <size android:height="50dp" /> </shape> The question is, how to make this line vertical? Yes, there are workarounds, such as drawing a rectangle shape 1px thick, but that complicates the drawable xml, if it consists of multiple <item> elements. Anyone had any chance with this?

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  • JQuery IE7 Z-Index Bug

    - by Thomas
    I built a Jquery dropdown menu using this tutorial: http://noupe.indexsite.org/tutorial/drop-down-menu-jquery-css.html It works across browsers except for IE7 (shooooocking). There seems to be a z-index sorting problem and the drop down menu shows up under all of my other JQuery elements. Im not sure how to set the z-index so that it shows up on top. I have thoroughly googled the issue and it seems to be related to multiple 'position:relative' elements. I've messed with it for a few hours but I can't seem to sort it out. I have already tried defining z-index for all the different page elements but it doesn't seem t help the situation. You can check out the problem here: http://hardtopdepot.com/dev/index.html Any help would be really appreciated - thanks! Also, I know there are other IE7 issues, but Im pretty confident that I can solve those as they are standard IE padding/margins nonsense.

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  • Formal Languages, Inductive Proofs &amp; Regular Expressions

    - by MarkPearl
    So I am slogging away at my UNISA stuff. I have just finished doing the initial once non stop read through the first 11 chapters of my COS 201 Textbook - “Introduction to Computer Theory 2nd Edition” by Daniel Cohen. It has been an interesting couple of days, with familiar concepts coming up as well as some new territory. In this posting I am going to cover the first couple of chapters of the book. Let start with Formal Languages… What exactly is a formal language? Pretty much a no duh question for me but still a good one to ask – a formal language is a language that is defined in a precise mathematical way. Does that mean that the English language is a formal language? I would say no – and my main motivation for this is that one can have an English sentence that is correct grammatically that is also ambiguous. For example the ambiguous sentence: "I once shot an elephant in my pyjamas.” For this and possibly many other reasons that I am unaware of, English is termed a “Natural Language”. So why the importance of formal languages in computer science? Again a no duh question in my mind… If we want computers to be effective and useful tools then we need them to be able to evaluate a series of commands in some form of language that when interpreted by the device no confusion will exist as to what we were requesting. Imagine the mayhem that would exist if a computer misinterpreted a command to print a document and instead decided to delete it. So what is a Formal Language made up of… For my study purposes a language is made up of a finite alphabet. For a formal language to exist there needs to be a specification on the language that will describe whether a string of characters has membership in the language or not. There are two basic ways to do this: By a “machine” that will recognize strings of the language (e.g. Finite Automata). By a rule that describes how strings of a language can be formed (e.g. Regular Expressions). When we use the phrase “string of characters”, we can also be referring to a “word”. What is an Inductive Proof? So I am not to far into my textbook and of course it starts referring to proofs and different types. I have had to go through several different approaches of proofs in the past, but I can never remember their formal names , so when I saw “inductive proof” I thought to myself – what the heck is that? Google to the rescue… An inductive proof is like a normal proof but it employs a neat trick which allows you to prove a statement about an arbitrary number n by first proving it is true when n is 1 and then assuming it is true for n=k and showing it is true for n=k+1. The idea is that if you want to show that someone can climb to the nth floor of a fire escape, you need only show that you can climb the ladder up to the fire escape (n=1) and then show that you know how to climb the stairs from any level of the fire escape (n=k) to the next level (n=k+1). Does this sound like a form of recursion? No surprise then that in the same chapter they deal with recursive definitions. An example of a recursive definition for the language EVEN would the 3 rules below: 2 is in EVEN If x is in EVEN then so is x+2 The only elements in the set EVEN are those that be produced by the rules above. Nothing to exciting… So if a definition for a language is done recursively, then it makes sense that the language can be proved using induction. Regular Expressions So I am wondering to myself what use is this all – in fact – I find this the biggest challenge to any university material is that it is quite hard to find the immediate practical applications of some theory in real life stuff. How great was my joy when I suddenly saw the word regular expression being introduced. I had been introduced to regular expressions on Stack Overflow where I was trying to recognize if some text measurement put in by a user was in a valid form or not. For instance, the imperial system of measurement where you have feet and inches can be represented in so many different ways. I had eventually turned to regular expressions as an easy way to check if my parser could correctly parse the text or not and convert it to a normalize measurement. So some rules about languages and regular expressions… Any finite language can be represented by at least one if not more regular expressions A regular expressions is almost a rule syntax for expressing how regular languages can be formed regular expressions are cool For a regular expression to be valid for a language it must be able to generate all the words in the language and no other words. This is important. It doesn’t help me if my regular expression parses 100% of my measurement texts but also lets one or two invalid texts to pass as well. Okay, so this posting jumps around a bit – but introduces some very basic fundamentals for the subject which will be built on in later postings… Time to go and do some practical examples now…

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  • Why would HTTP transfer via wget be faster than lftp/pget?

    - by jondahl
    I'm building software that needs to do massive amounts of file transfer via both HTTP and FTP. Often times, I get faster HTTP download with a multi-connection download accelerator like axel or lftp with pget. In some cases, I've seen 2x-3x faster file transfer using something like: axel http://example.com/somefile or lftp -e 'pget -n 5 http://example.com/somefile;quit' vs. just using wget: wget http://example.com/somefile But other times, wget is significantly faster than lftp. Strangly, this is even true even when I do lftp with get, like so: lftp -e 'pget -n 1 http://example.com/somefile;quit' I understand that downloading a file via multiple connections won't always result in a speedup, depending on how bandwidth is constrained. But: why would it be slower? Especially when calling lftp/pget with -n 1?

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  • Noftification between J2EE components.

    - by Pratik
    Hi There! I have a design problem . My application has multiple J2EE components ,In simple terms one acts as a service provider(Non UI) and others are consumers(UI webapp) . The consumer gets the configuration data from the service provider(this basically reads the data from DB) during the start up and stores it in the Cache. The cache gets refreshed after periodic time to reflect any changes done at the database. The Problem Apart from the cache refresh ,I also want to notify the consumers when someone changes the DB . that configuration has been changed please reload it. What notification mechanism's can I use to achieve this. Thanks! Pratik

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  • How to organize modules for PyPI to support 2.x and 3.x

    - by Craig McQueen
    I have a Python module that I would like to upload to PyPI. So far, it is working for Python 2.x. It shouldn't be too hard to write a version for 3.x now. But, after following guidelines for making modules in these places: Distributing Python Modules The Hitchhiker’s Guide to Packaging it's not clear to me how to support multiple source distributions for different versions of Python, and it's not clear if/how PyPI could support it. I envisage I would have separate code for: 2.x 2.6 (maybe, as a special case to use the new buffer API) 3.x How is it possible to set up a Python module in PyPI so that someone can do: easy_install modulename and it will install the right thing whether the user is using 2.x or 3.x?

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  • Relative Path To Absolute Path in VB .NET

    - by Mehdi Anis
    Hi, I am writing a VB .NET console app where it spits takes relative path and spits out all file name, or error for invalid input. I am havinf trouble getting PhysicalPath from RelativePath Example: ` 1. I am in folder: C:\Documents and Settings\MehdiAnis.ULTIMATEBANGLA\My Documents\Visual Studio 2005\Projects\SP_Sol\SP_Proj\bin\Debug My App SP.exe is also in the same folder I run: "SP.exe ..\" OutPut will be a list of all files in the folder of "C:\Documents and Settings\MehdiAnis.ULTIMATEBANGLA\My Documents\Visual Studio 2005\Projects\SP_Sol\SP_Proj\bin" I run: "SP.exe ..\..\" OutPut will be a list of all files in the folder of "C:\Documents and Settings\MehdiAnis.ULTIMATEBANGLA\My Documents\Visual Studio 2005\Projects\SP_Sol\SP_Proj" I run: "SP.exe ..\..\..\" OutPut will be a list of all files in the folder of "C:\Documents and Settings\MehdiAnis.ULTIMATEBANGLA\My Documents\Visual Studio 2005\Projects\SP_Sol" ` Currently I am Handling 1 relative path, but not more than one: If Source.IndexOf("..\") = 0 Then Dim Sibling As String = Directory.GetParent(Directory.GetCurrentDirectory()).ToString()()) Source = Source.Replace("..\", Sibling) End If How can I easily handle multiple ..\ easily ? Thanks.

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