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

  - by Senthil

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

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• Why does Hibernate 2nd level cache only cache queries within a session?

  - by Synesso

  Using a named query in our application and with ehcache as the provider, it seems that the query results are tied to the session within the cache. Any attempt to access the value from the cache for a second time results in a LazyInitializationException We have set lazy = true for the following mapping because this object is also used by another part of the system which does not require the reference... and we want to keep it lean. <class name="domain.ReferenceAdPoint" table="ad_point" mutable="false" lazy="false"> <cache usage="read-only"/> <id name="code" type="long" column="ad_point_id"> <generator class="assigned" /> </id> <property name="name" column="ad_point_description" type="string"/> <set name="synonyms" table="ad_point_synonym" cascade="all-delete-orphan" lazy="true"> <cache usage="read-only"/> <key column="ad_point_id" /> <element type="string" column="synonym_description" /> </set> </class> <query name="find.adpoints.by.heading">from ReferenceAdPoint adpoint left outer join fetch adpoint.synonyms where adpoint.adPointField.headingCode = ?</query> Here's a snippet from our hibernate.cfg.xml <property name="hibernate.cache.provider_class">net.sf.ehcache.hibernate.SingletonEhCacheProvider</property> <property name="hibernate.cache.use_query_cache">true</property> It doesn't seem to make sense that the cache would be constrained to the session. Why are the cached queries not usable outside of the (relatively short-lived) sessions?

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• Alternatives to static methods on interfaces for enforcing consistency

  - by jayshao

  In Java, I'd like to be able to define marker interfaces, that forced implementations to provide static methods. For example, for simple text-serialization/deserialization I'd like to be able to define an interface that looked something like this: public interface TextTransformable<T>{ public static T fromText(String text); public String toText(); Since interfaces in Java can't contain static methods though (as noted in a number of other posts/threads: here, here, and here this code doesn't work. What I'm looking for however is some reasonable paradigm to express the same intent, namely symmetric methods, one of which is static, and enforced by the compiler. Right now the best we can come up with is some kind of static factory object or generic factory, neither of which is really satisfactory. Note: in our case our primary use-case is we have many, many "value-object" types - enums, or other objects that have a limited number of values, typically carry no state beyond their value, and which we parse/de-parse thousands of time a second, so actually do care about reusing instances (like Float, Integer, etc.) and its impact on memory consumption/g.c. Any thoughts?

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• How to paginate Django with other get variables?

  - by vagabond

  I am having problems using pagination in Django. Take the URL below as an example: http://127.0.0.1:8000/users/?sort=first_name On this page I sort a list of users by their first_name. Without a sort GET variable it defaults to sort by id. Now if I click the next link I expect the following URL: http://127.0.0.1:8000/users/?sort=first_name&page=2 Instead I lose all get variables and end up with http://127.0.0.1:8000/users/?page=2 This is a problem because the second page is sorted by id instead of first_name. If I use request.get_full_path I will eventually end up with an ugly URL: http://127.0.0.1:8000/users/?sort=first_name&page=2&page=3&page=4 What is the solution? Is there a way to access the GET variables on the template and replace the value for the page? I am using pagination as described in Django's documentation and my preference is to keep using it. The template code I am using is similar to this: {% if contacts.has_next %} <a href="?page={{ contacts.next_page_number }}">next</a> {% endif %}

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• Adding label and text box control to GUI

  - by Mike

  I would like to know what code to insert and where to add a simple label that can just say the word "Label" and a input text box that I can enter a number. public CalculateDimensions() { JTabbedPane Tab = new JTabbedPane(); JPanel jplInnerPanel1 = createInnerPanel("First Tab"); Tab.addTab("One", jplInnerPanel1); Tab.setSelectedIndex(0); JPanel jplInnerPanel2 = createInnerPanel("Second Tab"); Tab.addTab("Two", jplInnerPanel2); JPanel jplInnerPanel3 = createInnerPanel("Third Tab"); Tab.addTab("Three", jplInnerPanel3); JPanel jplInnerPanel4 = createInnerPanel("Fourth Tab"); Tab.addTab("Four", jplInnerPanel4); JPanel jplInnerPanel5 = createInnerPanel("Fifth Tab"); Tab.addTab("Five", jplInnerPanel5); setLayout(new GridLayout(1, 1)); add(Tab); } protected JPanel createInnerPanel(String text) { JPanel jplPanel = new JPanel(); JLabel jlbDisplay = new JLabel(text); jlbDisplay.setHorizontalAlignment(JLabel.CENTER); jplPanel.setLayout(new GridLayout(1, 1)); jplPanel.add(jlbDisplay); return jplPanel; } public static void main(String[] args) { JFrame frame = new JFrame("Calculations"); frame.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } }); frame.getContentPane().add(new CalculateDimensions(), BorderLayout.CENTER); frame.setSize(400, 400); frame.setVisible(true); } }

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• Adjust width of td to make make row widths even

  - by user1729886

  I am trying to produce a table with a different number of cells in each row. The first row is a header row (every other row contains cells). This header is the width of the table. The second row has 2 cells in it... the third has 1 cell... the fourth has 4 cells... the fifth and final row has 3 cells. I want the table set up so that the rows span the full width of the table. If the table is 1000px... The header would be 1000px wide the cells in the 2nd row would be 500px EACH the cell in the 3rd row would be 1000px the cells in the 4th row would be 250px EACH and the cells in the 5th row would be 333px, 334px, and 333px each (left-to-right) I figured out I could use colspan for the first 4 rows, but the 5th (with 3 cells) would require a non-integer value. The cells in the 5th row won't expand beyond their column without colspan that I can tell... trying the width:## CSS code inside a div tag for each cell inside the td tag creating a class or classes that define the cell widths id-ing each cell, with or without a div tag, and defining widths individually and adjuting the table-layout: option After several days, I'm now at my rope's end. The only thing I can come up with is deliberately tripling the number of cells in each row so that colspan would be all integer values. That sounds inconvenient and unreasonably difficult to format the table the way I'd like. It's a table of Batman movies for a website -- a practice website I'm building, in order to learn HTML/CSS. I've been working on-and-off with HTML for several months, and CSS for a few weeks. PS: It is not being used for layout, I am simply trying to adjust the layout of the table itself.

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• Why are compilers so stupid?

  - by martinus

  I always wonder why compilers can't figure out simple things that are obvious to the human eye. They do lots of simple optimizations, but never something even a little bit complex. For example, this code takes about 6 seconds on my computer to print the value zero (using java 1.6): int x = 0; for (int i = 0; i < 100 * 1000 * 1000 * 1000; ++i) { x += x + x + x + x + x; } System.out.println(x); It is totally obvious that x is never changed so no matter how often you add 0 to itself it stays zero. So the compiler could in theory replace this with System.out.println(0). Or even better, this takes 23 seconds: public int slow() { String s = "x"; for (int i = 0; i < 100000; ++i) { s += "x"; } return 10; } First the compiler could notice that I am actually creating a string s of 100000 "x" so it could automatically use s StringBuilder instead, or even better directly replace it with the resulting string as it is always the same. Second, It does not recognize that I do not actually use the string at all, so the whole loop could be discarded! Why, after so much manpower is going into fast compilers, are they still so relatively dumb? EDIT: Of course these are stupid examples that should never be used anywhere. But whenever I have to rewrite a beautiful and very readable code into something unreadable so that the compiler is happy and produces fast code, I wonder why compilers or some other automated tool can't do this work for me.

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• How do you keep text from wrapping in an NSTableView using NSAttributedString

  - by Justin

  I have an NSTableView that has 2 columns, one for an icon and the other for two lines of text. In the second column, the text column, I have some larger text that is for the name of an item. Then I have a new line and some smaller text that describes the state of the item. When the name becomes so large that it doesn't fit on one line it wraps (or when you shrink the window down so small that it causes the names to not fit on a single line). row1=============== | image |  some name   | | image |   idle               | row2================ | image |  some name really long name   | <- this gets wrapped pushing 'idle' out of the view | image |   idle               | =================== My question is, how could I keep the text from wrapping and just have the NSTableView display a horizontal scroll-bar once the name is too large to fit?

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• Counting in R data.table

  - by Simon Z.

  I have the following data.table set.seed(1) DT <- data.table(VAL = sample(c(1, 2, 3), 10, replace = TRUE)) VAL 1: 1 2: 2 3: 2 4: 3 5: 1 6: 3 7: 3 8: 2 9: 2 10: 1 Now I want to to perform two tasks: Count the occurrences of numbers in VAL. Count within all rows with the same value VAL (first, second, third occurrence) At the end I want the result VAL COUNT IDX 1: 1 3 1 2: 2 4 1 3: 2 4 2 4: 3 3 1 5: 1 3 2 6: 3 3 2 7: 3 3 3 8: 2 4 3 9: 2 4 4 10: 1 3 3 where COUNT defines task 1. and IDX task 2. I tried to work with which and length using .I: dt[, list(COUNT = length(VAL == VAL[.I]), IDX = which(which(VAL == VAL[.I]) == .I))] but this does not work as .I refers to a vector with the index, so I guess one must use .I[]. Though inside .I[] I again face the problem, that I do not have the row index and I do know (from reading data.table FAQ and following the posts here) that looping through rows should be avoided if possible. So, what's the data.table way?

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• Most Elegant Way to write isPrime in java

  - by Anantha Kumaran

  public class Prime { public static boolean isPrime1(int n) { if (n <= 1) { return false; } if (n == 2) { return true; } for (int i = 2; i <= Math.sqrt(n) + 1; i++) { if (n % i == 0) { return false; } } return true; } public static boolean isPrime2(int n) { if (n <= 1) { return false; } if (n == 2) { return true; } if (n % 2 == 0) { return false; } for (int i = 3; i <= Math.sqrt(n) + 1; i = i + 2) { if (n % i == 0) { return false; } } return true; } } public class PrimeTest { public PrimeTest() { } @Test public void testIsPrime() throws IllegalArgumentException, IllegalAccessException, InvocationTargetException { Prime prime = new Prime(); TreeMap<Long, String> methodMap = new TreeMap<Long, String>(); for (Method method : Prime.class.getDeclaredMethods()) { long startTime = System.currentTimeMillis(); int primeCount = 0; for (int i = 0; i < 1000000; i++) { if ((Boolean) method.invoke(prime, i)) { primeCount++; } } long endTime = System.currentTimeMillis(); Assert.assertEquals(method.getName() + " failed ", 78498, primeCount); methodMap.put(endTime - startTime, method.getName()); } for (Entry<Long, String> entry : methodMap.entrySet()) { System.out.println(entry.getValue() + " " + entry.getKey() + " Milli seconds "); } } } I am trying to find the fastest way to check whether the given number is prime or not. This is what is finally came up with. Is there any better way than the second implementation(isPrime2).

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• URLLoader.load() issue when using the same URLRequest

  - by Rudy

  Hello, I have an issue with my eventListeners with the URLLoader, but this issue happens in IE, not in FF. public function getUploadURL():void { var request:URLRequest = new URLRequest(); request.url = getPath(); request.method = URLRequestMethod.GET; _loader = new URLLoader(); _loader.dataFormat = URLLoaderDataFormat.TEXT; _loader.addEventListener(Event.COMPLETE, getBaseURL); _loader.load(request); } private function getBaseURL(event:Event):void { _loader.removeEventListener(Event.COMPLETE, getBaseURL); } The issue is that my getBaseURL gets executed automatically after I have executed the code at least once, but that is the case only in IE. What happens is I call my getUploadURL, I make sure the server sends an event that will result in an Event.COMPLETE, so the getBaseURL gets executed, and the listener is removed. If I call the getUploadURL method and put the wrong path, I do not get an Event.COMPLETE but some other event, and getBaseURL should not be executed. That is the correct behavior in FireFox. In IE, it looks like the load() method does not actually call the server, it jumps directly to the getBaseURL() for the Event.COMPLETE. I checked the willTrigger() and hasEventListener() on _loader before assigning the new URLLoader, and it turns out the event has been well removed. I hope I make sense, I simplified my code. To sum up quickly: in FireFox it works well, but in IE, the first call will work but the second call won't really call the .load() method; it seems it uses the previously stored result from the first call. I hope someone can please help me, Thank you, Rudy

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• How to send Event signal through Processes - C

  - by Jamie Keeling

  Hello all! I have an application consisting of two windows, one communicates to the other and sends it a struct constaining two integers (In this case two rolls of a dice). I will be using events for the following circumstances: Process a sends data to process b, process b displays data Process a closes, in turn closing process b Process b closes a, in turn closing process a I have noticed that if the second process is constantly waiting for the first process to send data then the program will be just sat waiting, which is where the idea of implementing threads on each process occurred and I have started to implement this already. The problem i'm having is that I don't exactly have a lot of experience with threads and events so I'm not sure of the best way to actually implement what I want to do. I'm trying to work out how the other process will know of the event being fired so it can do the tasks it needs to do, I don't understand how one process that is separate from another can tell what the states the events are in especially as it needs to act as soon as the event has changed state. Thanks for any help Edit: I can only use the Create/Set/Open methods for events, sorry for not mentioning it earlier.

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• ASP.NET MVC 2 user input to SQL 2008 Database problems

  - by Rob

  After my publish in VS2010 the entire website loads and pulls data from the database perfectly. I can even create new users through the site with the correct key code, given out to who needs access. I have two connection strings in my web.config file The first: <add xdt:Transform="SetAttributes" xdt:Locator="Match(name)" name="EveModelContainer" connectionString="metadata=res://*/Models.EdmModel.EveModel.csdl|res://*/Models.EdmModel.EveModel.ssdl|res://*/Models.EdmModel.EveModel.msl;provider=System.Data.SqlClient;provider connection string=&quot;Data Source=localhost;Initial Catalog=fleet;Persist Security Info=True;User ID=fleet;Password=****&quot;" providerName="System.Data.EntityClient" /> The second: <add xdt:Transform="SetAttributes" xdt:Locator="Match(name)" name="ApplicationServices" connectionString="Data Source=localhost;Initial Catalog=fleet;Persist Security Info=True;User ID=fleet;Password=****;MultipleActiveResultSets=True" /> The first one is the one that is needed to post data with the main application, EveModelContainer. Everything else is pulled using the standard ApplicationServices connection. Do you see anything wrong with my connectionstring? I'm at a complete loss here. The site works perfectly on my friends server and not on mine... Could it be a provider issue? And if I go to iis 7's manager console, and click .net users I get a pop up message saying the custom provider isn't a trusted provider do I want to allow it to run at a higher trust level. I'm at the point where I think its either my string or this trusted provider error... but I have no clue how to add to the trusted provider list... Thank you in advance!!!

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• While loop problems

  - by Luke

  I have put together the following code, the problem is that each while loop is only returning one set of data. $result = mysql_query("SELECT date FROM ".TBL_FIXTURES." WHERE compname = '$comp_name' GROUP BY date"); $i = 1; echo "<table cellspacing=\"10\" style='border: 1px dotted' width=\"300\" bgcolor=\"#eeeeee\">"; while ($row = mysql_fetch_assoc($result)) { $date=date("F j Y", $row['date']); echo $date; echo " <tr> <td>Fixture $i - Deadline on $date</td> </tr> "; $result = mysql_query("SELECT * FROM ".TBL_FIXTURES." WHERE compname = '$comp_name' AND date = '$row[date]' ORDER BY date"); while ($row = mysql_fetch_assoc($result)) { extract ($row); echo " <tr> <td>$home_user - $home_team V $away_user - $away_team</td> </tr> "; } $i++; } echo "</table>"; I should get many dates, and then each set of fixture below. At the moment, the first row from the first while loop is present, along with the data from the second while loop. However, it doesn't continue? Any ideas where I can correct this? Thanks

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• Is it possible to refer to metadata of the target from within the target implementation in MSBuild?

  - by mark

  Dear ladies and sirs. My msbuild targets file contains the following section: <ItemGroup> <Targets Include="T1"> <Project>A\B.sln"</Project> <DependsOnTargets>The targets T1 depends on</DependsOnTargets> </Targets> <Targets Include="T2"> <Project>C\D.csproj"</Project> <DependsOnTargets>The targets T2 depends on</DependsOnTargets> </Targets> ... </ItemGroup> <Target Name="T1" DependsOnTargets="The targets T1 depends on"> <MSBuild Projects="A\B.sln" Properties="Configuration=$(Configuration)" /> </Target> <Target Name="T2" DependsOnTargets="The targets T2 depends on"> <MSBuild Projects="C\D.csproj" Properties="Configuration=$(Configuration)" /> </Target> As you can see, A\B.sln appears twice: As Project metadata of T1 in the ItemGroup section. In the Target statement itself passed to the MSBuild task. I am wondering whether I can remove the second instance and replace it with the reference to the Project metadata of the target, which name is given to the Target task? Exactly the same question is asked for the (Targets.DependsOnTargets) metadata. It is mentioned twice much like the %(Targets.Project) metadata. Thanks. EDIT: I should probably describe the constraints, which must be satisfied by the solution: I want to be able to build individual projects with ease. Today I can simply execute msbuild file.proj /t:T1 to build the T1 target and I wish to keep this ability. I wish to emphasize, that some projects depend on others, so the DependsOnTargets attribute is really necessary for them.

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• Parse a CSV file using python (to make a decision tree later)

  - by Margaret

  First off, full disclosure: This is going towards a uni assignment, so I don't want to receive code. :). I'm more looking for approaches; I'm very new to python, having read a book but not yet written any code. The entire task is to import the contents of a CSV file, create a decision tree from the contents of the CSV file (using the ID3 algorithm), and then parse a second CSV file to run against the tree. There's a big (understandable) preference to have it capable of dealing with different CSV files (I asked if we were allowed to hard code the column names, mostly to eliminate it as a possibility, and the answer was no). The CSV files are in a fairly standard format; the header row is marked with a # then the column names are displayed, and every row after that is a simple series of values. Example: # Column1, Column2, Column3, Column4 Value01, Value02, Value03, Value04 Value11, Value12, Value13, Value14 At the moment, I'm trying to work out the first part: parsing the CSV. To make the decisions for the decision tree, a dictionary structure seems like it's going to be the most logical; so I was thinking of doing something along these lines: Read in each line, character by character If the character is not a comma or a space Append character to temporary string If the character is a comma Append the temporary string to a list Empty string Once a line has been read Create a dictionary using the header row as the key (somehow!) Append that dictionary to a list However, if I do things that way, I'm not sure how to make a mapping between the keys and the values. I'm also wondering whether there is some way to perform an action on every dictionary in a list, since I'll need to be doing things to the effect of "Everyone return their values for columns Column1 and Column4, so I can count up who has what!" - I assume that there is some mechanism, but I don't think I know how to do it. Is a dictionary the best way to do it? Would I be better off doing things using some other data structure? If so, what?

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• How do I reference my MainViewController from another class?

  - by todd412

  Hi, I am building an iPhone Utility app that uses UIImageView to display an animation. Within the MainViewController's viewDidLoad() method, I am creating an instance of a CustomClass, and then setting up the animations: - (void)viewDidLoad { [super viewDidLoad]; cc = [CustomClass new]; NSArray * imageArray = [[NSArray alloc] initWithObjects: [UIImage imageNamed:@"image-1-off.jpg"], [UIImage imageNamed:@"image-2-off.jpg"], [UIImage imageNamed:@"image-3-off.jpg"], [UIImage imageNamed:@"image-4-off.jpg"], nil]; offSequence = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 320, 480)]; offSequence.animationImages = imageArray; offSequence.animationDuration = .8; offSequence.contentMode = UIViewContentModeBottomLeft; [self.view addSubview:offSequence]; [offSequence startAnimating]; } That works fine. However, I would like to be able to move all the above code that sets up the UIImageView into my CustomClass. The problem is in the second to last line: [self.view addSubview:offSequence]; I basically need to replace 'self' with a reference to the MainControllerView, so I can call addSubview from within my CustomClass. I tried creating an instance var of CustomClass called mvc and a setter method that takes a reference to the MainViewController as an argument as such: - (void) setMainViewController: (MainViewController *) the_mvc { mvc = the_mvc; } And then I called it within MainViewController like so: [cc setMainController:MainViewController:self]; But this yields all sorts of errors which I can post here, but it strikes me that I may be overcomplicating this. Is there an easier way to reference the MainViewController that instanatiated my CustomClass?

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• Windows loader problem - turn on verbose mode

  - by doobop

  Hi, I'm in the process of reorganizing some of the legacy libraries in our application which has unmanaged code calling into libraries of managed code. While I have the code reorganized, it produces the following loader error: ... 'app.exe': Loaded 'C:\WINDOWS\system32\CsDisp.dll' 'app.exe': Loaded 'C:\WINDOWS\system32\psapi.dll' 'app.exe': Loaded 'C:\WINDOWS\system32\shell32.dll' 'app.exe': Loaded 'C:\appCode\Debug\daq206_32.dll', Binary was not built with debug information. 'app.exe': Loaded 'C:\appCode\Debug\SiUSBXp.dll', Binary was not built with debug information. 'app.exe': Loaded 'C:\appCode\Debug\AdlinkDAQ.dll', Symbols loaded. 'app.exe': Loaded 'C:\WINDOWS\system32\P9842.dll', Binary was not built with debug information. LDR: LdrRelocateImageWithBias() failed 0xc0000018 LDR: OldBase : 10000000 LDR: NewBase : 00A80000 LDR: Diff : 0x7c90d6fa0012f6cc LDR: NextOffset : 00000000 LDR: *NextOffset : 0x0 LDR: SizeOfBlock : 0xa80000 Debugger:: An unhandled non-continuable exception was thrown during process load I believe 0xc0000018 error is an overlapping address range. So, I have two questions. First, what linker options may cause this error? I'm currently linking with /DYNAMICBASE:NO and /FIXED:No as this was how some of the previous libraries were set up. Second, is there a way to turn on verbose mode for the loader so I can see what exactly it's trying to load? P9842 is a third party library so I imagine it is getting to one of my libraries after P9842 and failing on that one. Can I narrow it down? Thanks.

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• ASP.NET 2.0 + Firefox/Safari - UI Issues?

  - by Tejaswi Yerukalapudi

  I'm developing on a system that was originally developed five years ago. I don't have access to the complete source code of the system, but it is completely driven by XML and runs on ASP.NET 2.0. This was originally written for IE6, but since Microsoft has officially decided to dump it, we moved to IE7. Some javascript is added on the client side, but nothing that changes the UI has been done. (We had to integrate a credit card reader into the system) This code is accessed primarily on tablet PCs running windows, but I'd like to persuade my company to use the iPad. [The tablet somehow costs around 3k$. I think selling a 3000$ device to a client when you have the iPad for 500$ is ridiculous.] Now, my problem is if we open it in any other browser (Tested it on safari / firefox), the UI is completely messed up with elements completely out of place. Doesn't ASP.NET generate HTML that runs on any browser? My second question is if there are any credit card readers available in the market that integrate with the iPad. I don't really care about the software part as it's taken care by our company, I just need it to read the card details and post it to the server. Thanks, Teja.

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• Problem in DataBinding an Enum using dictionary approach to a combobox in WPF.

  - by Ashish Ashu

  I have a Dictionary which is binded to a combobox. I have used dictionary to provide spaces in enum. public enum Option {Enter_Value, Select_Value}; Dictionary<Option,string> Options; <ComboBox x:Name="optionComboBox" SelectionChanged="optionComboBox_SelectionChanged" SelectedValuePath="Key" DisplayMemberPath="Value" SelectedItem="{Binding Path = SelectedOption}" ItemsSource="{Binding Path = Options}" /> This works fine. My queries: 1. I am not able to set the initial value to a combo box. In above XAML snippet the line SelectedItem="{Binding Path = SelectedOption}" is not working. I have declared SelectOption in my viewmodel. This is of type string and I have intialized this string value in my view model as below: SelectedOption = Options[Options.Enter_Value].ToString(); 2. The combobox is binded to datadictionary which have two options first is "Enter_value" and second is "Select_value" which is actually Option enum. Based on the Option enum value I want to perform different action. For example if option is equal to option.Enter_value then Combo box becomes editable and user can enter the numeric value in it. if option is equal to option.Select_value value then the value comes from the database and the combo box becomes read only and shows the fetched value from the database. Please Help!!

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• Attach an entity that is not new, perhaps having been loaded from another DataContext. LINQ to SQL -

  - by soldieraman

  Alright How I got this error I got one application sitting on a server 2 users accessing this application - doing some bulk data processing . eg. entering values and then the application is working with another system to extract values for them and then saving. I can't recreate the error The error logs show: The error happend at the same time in both the application Both happend on a Attach/Submit (but two different functions) There is no way they are using the same DataContext object as I save the DataContext in the HttpContext.Items My hunch / guess is: One datacontext was not refreshed i.e. the an object was created for the same item twice as it was new in both the forms. eg. Customer Number - a customer was created (as one couldn't be found) by one datacontext - the other one couldn't find it either (i am using compiled queries to find it in the datacontext) so it created another object and on attaching failed. The HttpContext.Items lost its value somehow (i am using a virtual pc as server - maybe something went wrong there) I am going more of the second as I can't recreate the error - but it just might be a timing (for attach/save) thing - also the error makes me think of the 2nd too.

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• vectorizing loops in Matlab - performance issues

  - by Gacek

  This question is related to these two: http://stackoverflow.com/questions/2867901/introduction-to-vectorizing-in-matlab-any-good-tutorials http://stackoverflow.com/questions/2561617/filter-that-uses-elements-from-two-arrays-at-the-same-time Basing on the tutorials I read, I was trying to vectorize some procedure that takes really a lot of time. I've rewritten this: function B = bfltGray(A,w,sigma_r) dim = size(A); B = zeros(dim); for i = 1:dim(1) for j = 1:dim(2) % Extract local region. iMin = max(i-w,1); iMax = min(i+w,dim(1)); jMin = max(j-w,1); jMax = min(j+w,dim(2)); I = A(iMin:iMax,jMin:jMax); % Compute Gaussian intensity weights. F = exp(-0.5*(abs(I-A(i,j))/sigma_r).^2); B(i,j) = sum(F(:).*I(:))/sum(F(:)); end end into this: function B = rngVect(A, w, sigma) W = 2*w+1; I = padarray(A, [w,w],'symmetric'); I = im2col(I, [W,W]); H = exp(-0.5*(abs(I-repmat(A(:)', size(I,1),1))/sigma).^2); B = reshape(sum(H.*I,1)./sum(H,1), size(A, 1), []); But this version seems to be as slow as the first one, but in addition it uses a lot of memory and sometimes causes memory problems. I suppose I've made something wrong. Probably some logic mistake regarding vectorizing. Well, in fact I'm not surprised - this method creates really big matrices and probably the computations are proportionally longer. I have also tried to write it using nlfilter (similar to the second solution given by Jonas) but it seems to be hard since I use Matlab 6.5 (R13) (there are no sophisticated function handles available). So once again, I'm asking not for ready solution, but for some ideas that would help me to solve this in reasonable time. Maybe you will point me what I did wrong.

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• How do I find all paths through a set of given nodes in a DAG?

  - by Hanno Fietz

  I have a list of items (blue nodes below) which are categorized by the users of my application. The categories themselves can be grouped and categorized themselves. The resulting structure can be represented as a Directed Acyclic Graph (DAG) where the items are sinks at the bottom of the graph's topology and the top categories are sources. Note that while some of the categories might be well defined, a lot is going to be user defined and might be very messy. Example: On that structure, I want to perform the following operations: find all items (sinks) below a particular node (all items in Europe) find all paths (if any) that pass through all of a set of n nodes (all items sent via SMTP from example.com) find all nodes that lie below all of a set of nodes (intersection: goyish brown foods) The first seems quite straightforward: start at the node, follow all possible paths to the bottom and collect the items there. However, is there a faster approach? Remembering the nodes I already passed through probably helps avoiding unnecessary repetition, but are there more optimizations? How do I go about the second one? It seems that the first step would be to determine the height of each node in the set, as to determine at which one(s) to start and then find all paths below that which include the rest of the set. But is this the best (or even a good) approach? The graph traversal algorithms listed at Wikipedia all seem to be concerned with either finding a particular node or the shortest or otherwise most effective route between two nodes. I think both is not what I want, or did I just fail to see how this applies to my problem? Where else should I read?

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• Two radically different queries against 4 mil records execute in the same time - one uses brute force.

  - by IanC

  I'm using SQL Server 2008. I have a table with over 3 million records, which is related to another table with a million records. I have spent a few days experimenting with different ways of querying these tables. I have it down to two radically different queries, both of which take 6s to execute on my laptop. The first query uses a brute force method of evaluating possibly likely matches, and removes incorrect matches via aggregate summation calculations. The second gets all possibly likely matches, then removes incorrect matches via an EXCEPT query that uses two dedicated indexes to find the low and high mismatches. Logically, one would expect the brute force to be slow and the indexes one to be fast. Not so. And I have experimented heavily with indexes until I got the best speed. Further, the brute force query doesn't require as many indexes, which means that technically it would yield better overall system performance. Below are the two execution plans. If you can't see them, please let me know and I'll re-post then in landscape orientation / mail them to you. Brute-force query: Index-based exception query: My question is, based on the execution plans, which one look more efficient? I realize that thing may change as my data grows.

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• Javascript "Match" Function Not Returning Proper Results in Safari or IE (but yes in FF)

  - by Jascha

  Forgive me as this is a time sensitive issue and I will have to switch the site back in a few hours so the link will be bad... but: I am simply comparing two strings looking for a match with this function... I have an array of objects called linkArray and I need to match the .src of each object to a .src I send it (the src of the clicked image). if the the src of the image I clicked matches the src of an object in my array, I set a variable to the link string of that object and return true, letting my page know that the link is available. Now, this works great in FF. But not in any other browser and I can't figure out for the life of me why. I have set up a dialogue box to literally compare, by eye, the two strings that should at the very least throw the message "match". Can anyone see what I am missing here??? here is the link... http://7thart.com/Jewish-History-and-Culture/Jews-and-Baseball-An-American-Love-Story If you click any of the thumbnails on the left, you will activate the function. Again, I apologize as after a few hours I have to switch back to the original site and this link will be invalid. Thanks in advance for your help. (function below)... function matchLink(a){ for(var i=0;i<linkArray.length;i++){ var fixLink = '../' + linkArray[i]['src']; alert(fixLink + '\n = \n' + a); if(fixLink == a){ alert('match'); newLink = linkArray[i]['link']; return true; } } return false; } Note: The "match" will return on two of the images.. the initial image, and the first thumbnail on the left. The second thumbnail SHOULD match, and the third one SHOULD NOT match.

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