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  • ADO.NET zombie transaction bug? How to ensure that commands will not be executed on implicit transac

    - by TN
    e.g. When deadlock occurs, following SQL commands are successfully executed, even if they have assigned SQL transaction that is after rollback. It seems, it is caused by a new implicit transaction that is created on SQL Server. Someone could expect that ADO.NET would throw an exception that the commands are being executed on a zombie transaction. However, such exception is not thrown. (I think this is a bug in ASP.NET.) Moreover, because of zombie transaction the final Dispose() silently ignores the rollback. Any ideas, how can I ensure that nobody can execute commands on implicit transaction? Or, how to check that transaction is zombie? I found that Commit() and Rollback() check for zombie transaction, however I can call them for a test:) I also found that also reading IsolationLevel will do the check, but I am not sure whether simple calling transaction.IsolationLevel.ToString(); will not be removed by a future optimizer. Or do you know any other safe way invoke a getter (without using reflection or IL emitting)?

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  • Dependency Injection for objects that require parameters

    - by Andrew
    All of our reports are created from object graphs that are translated from our domain objects. To enable this, we have a Translator class for each report, and have been using Dependency Injection for passing in dependencies. This worked great, and would yield nice classes structured like this: public class CheckTranslator : ICheckTranslator { public CheckTranslator (IEmployeeService empSvc , IPaycheckService paySvc) { _empSvc = empSvc; _paySvc = paySvc; } public Check CreateCheck() { //do the translation... } } However, in some cases the mapping has many different grouping options. As a result, the c-tor would turn into a mix of class dependencies and parameters. public class CheckTranslator : ICheckTranslator { public CheckTranslator (IEmployeeService empSvc , IPaycheckService paySvc , bool doTranslateStubData , bool doAttachLogo) { _empSvc = empSvc; _paySvc = paySvc; _doTranslateStubData = doTranslateStubData; _doAttachLogo = doAttachLogo; } public Check CreateCheck() { //do the translation... } } Now, we can still test it, but it no longer really works with an IoC container, at least in a clean fashion. Plus, we can no longer call the CreateCheck twice if the settings are different for each check. While I recognize it's a problem, I don't necessarily see the right solution. It seems kind of strange to create a Factory for each class ... or is this the best way?

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  • How to test a struts 2.1.x developer?

    - by Jason Pyeron
    We employ test to filter out those who can't. The tests are designed to be very low effort for those who can and too much effort for those who can't. Here is an example for java web application developer on an Oracle project: We only work with contractors who can use the tools we use, to determine if you can use the tools we have devised some very simple tests. Instructions If you are prepared and knowledgeable this will take you about 2-5 minutes. Suggested knowledge and tools: * subversion 1.6 see http://subversion.tigris.org/ or http://cygwin.com/setup.exe * java 1.6 see http://java.sun.com/javase/downloads/index.jsp * oracle >=10g see http://www.oracle.com/technology/software/products/jdev/index.html * j2ee server see http://tomcat.apache.org/download-55.cgi or http://www.jboss.org/jbossas/downloads/ Steps 1. check out svn://statics32.pdinc.us/home/subversion/guest 2. deploy the war file found at trunk/test.war 3. browse to the web application you installed from the war file and answer the one SQL question: How many rows are in the table 'testdata' where column 'value' ends with either an 'A' or an 'a'? The login credentials are in trunk/doc/oracle.txt 4. make a RESULTS HASH by submitting your answer to the form. 5. create a file in tmp/YourUserName.txt and put the RESULTS HASH in it, not the answer. 6. check in your file (don't forget to add the file first). 7. message me with the revision number of your check in. As such I am looking for ideas on how to test for someone to be a struts 2.1 w/ annotations.

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  • Entity Framework and stored procedure returning temp table Issues

    - by kaplooeymom
    (Disclaimer - I'm not the database designer. I'm just the poor developer what has to make this work.) There are 17 (at the moment) tables with identical structure - name, address, phone number. Given a phone number, I have to check to see if there's a matching entry in any of the tables, then return that address. So, I created a view to get the list of tables (there's a ref table that holds that info), then I created a stored procedure to create a temp table, using cursors, check each table in the view for the phone number, using sql concatenation. If a record is found, insert it into the temp table. return the rows from the temp table. This all works in straight T-SQL. Now, I'm trying to use Entity Framework 4+ to call the stored procedure. But the function import interface won't generate columns. It says return type = none, and the LINQ code expects an int and won't compile. Any ideas on how to make this work? I know I can move the check tables part to code, if I absolutely have to, but I'd rather have the above method work.

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  • Errors In Programmatically Running ANT Build In Eclipse

    - by Sujay
    I am trying to run an ANT script through a small Java program and I keep on encountering the following error: build: Exception in thread "main" build.xml:7: Problem: failed to create task or type eclipse.refreshLocal Cause: The name is undefined. Action: Check the spelling. Action: Check that any custom tasks/types have been declared. Action: Check that any <presetdef>/<macrodef> declarations have taken place. at org.apache.tools.ant.UnknownElement.getNotFoundException(UnknownElement.java:487) at org.apache.tools.ant.UnknownElement.makeObject(UnknownElement.java:419) at org.apache.tools.ant.UnknownElement.maybeConfigure(UnknownElement.java:163) I used to get this problem when I used to execute the build file manually. All I had to do to make Eclipse run this build was to go to Run External Tools External Tools Configuration JRE and select "Run in the same JRE as the workspace" and then attempt to execute. But I have no idea how to achieve the same effect through my code. Any suggestion would really be appreciated. Note that this has reference to a previous question that I asked over here

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  • JSF/ADF/PPR can't refresh the page as expected

    - by Nhut Le
    Hi, I am having issues with JSF/ADF/PPR on refreshing the page incorrectly. I have a selectManyCheckBox with 5 options in it, one of the option is 'All'. If users check that checkbox, I should check all the others. <h:panelGrid styleClass="myBox leftAligned" id="applyChangesBox"> <af:selectManyCheckbox id="changesCheckedBox" autoSubmit="true" label="Hello: " value="#{updateForm.applyChangesList}" valueChangeListener="#{updateForm.testValueChanged}"> <af:selectItem value="A" label="All Changes"/> <af:selectItem value="R" label="Residential Address"/> <af:selectItem value="M" label="Mailing Address"/> <af:selectItem value="P" label="Personal Phone/Fax Numbers"/> <af:selectItem value="E" label="Personal Email Addresses"/> </af:selectManyCheckbox> <af:outputText value="#{updateForm.testValue}" partialTriggers="changesCheckedBox"/> </h:panelGrid> I am using valueChangeListener so that I can see my bean updated and printed out correctly, but my page does not refresh and check all the other checkbox if I need to.

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  • How to implement "business rules" in Rails?

    - by Zabba
    What is the way to implement "business rules" in Rails? Let us say I have a car and want to sell it: car = Cars.find(24) car.sell car.sell method will check a few things: does current_user own the car? check: car.user_id == current_user.id is the car listed for sale in the sales catalog? check: car.catalogs.ids.include? car.id if all o.k. then car is marked as sold. I was thinking of creating a class called Rules: class Rules def initialize(user,car) @user = user @car = car end def can_sell_car? @car.user_id == @user.id && @car.catalogs.ids.include? @car.id end end And using it like this: def Car def sell if Rules.new(current_user,self).can_sell_car ..sell the car... else @error_message = "Cannot sell this car" nil end end end As for getting the current_user, I was thinking of storing it in a global variable? I think that whenever a controller action is called, it's always a "fresh" call right? If so then storing the current user as a global variable should not introduce any risks..(like some other user being able to access another user's details) Any insights are appreciated! UPDATE So, the global variable route is out! Thanks to PeterWong for pointing out that global variables persist! I've now thinking of using this way: class Rules def self.can_sell_car?(current_user, car) ......checks.... end end And then calling Rules.can_sell_car?(current_user,@car) from the controller action. Any thoughts on this new way?

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  • JavaFX: JNLP file error

    - by jeff porter
    Hello everyone, I'm getting the following error when I upload a JavaFX app to a website, but I don't get it locally. I'm presuming that I'm missing something like the 'codebase' tag, but I'm not sure where it goes, can anyone help me out please? Java Console error: exception: JNLP file error: iShout_Foxpro_browser.jnlp. Please make sure the file exists and check if "codebase" and "href" in the JNLP file are correct.. java.io.FileNotFoundException: JNLP file error: iShout_Foxpro_browser.jnlp. Please make sure the file exists and check if "codebase" and "href" in the JNLP file are correct. at sun.plugin2.applet.JNLP2Manager.loadJarFiles(Unknown Source) at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source) at java.lang.Thread.run(Unknown Source) Exception: java.io.FileNotFoundException: JNLP file error: iShout_Foxpro_browser.jnlp. Please make sure the file exists and check if "codebase" and "href" in the JNLP file are correct. HTML file source... <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>app_one</title> </head> <body> <script src="http://dl.javafx.com/1.3/dtfx.js"></script> <script> javafx( { archive: "app_one.jar", draggable: true, width: 480, height: 320, code: "app.Main", name: "app_one" } );

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  • php mysql parallel array checkboxes

    - by gramware
    I have an array of checkboxes that I edit at once to set up a 'tinyint' field. the problem comes in when i uncheck the checkbox and post the vales to mysql. since it posts an array of checkboxes and another parallel array of values to edit, unchecking a checkbox results in the 0 value been ignored by PHP_POST and hence the checkbox array will be less by the number of unchecked values in the form while the array to be edited will have all the records in the form. here is the submit code while($row=mysql_fetch_array($result)) { $checked = ($row[active]==1) ? 'checked="checked"' : ''; ... echo "<input type='hidden' name='TrID[]' value='$TrID'>"; echo "<input type='checkbox' name='active1[]' value='$row[active]''$checked' >"; ... and the processing php script $userid = ($_POST['TrID']); $checked= ($_POST['active']); $i=0; foreach ($userid as $usid) { if ($checked[$i]==1){ $check = 1; } else{ $check = 0; } $qry1 ="UPDATE `epapers`.`clientelle` SET `active` = '$check' WHERE `clientelle`.`user_id` = '$usid' "; $result = mysql_query($qry1); $i++; }

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  • CheckBox won't toggle in Android ListView with focusable="false"

    - by user3563124
    I'm creating a ListView with a custom Adapter for displaying my entries. Each row contains a checkbox, and my adapter contains the following code: CheckBox cb = (CheckBox) v.findViewById(R.id.item_sold); cb.setChecked(p.isSold); setupCheckboxListener(cb, v, position); ... private void setupCheckboxListener(CheckBox check, final View v, final int position) { check.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { CheckBox cb = (CheckBox) v; if (cb.isChecked()) { System.out.println("Should become false!"); cb.setChecked(false); } else { System.out.println("Should become true!"); cb.setChecked(true); } } }); My row XML file includes the following: <CheckBox android:id="@+id/item_sold" android:layout_width="0dp" android:layout_height="wrap_content" android:layout_weight="0.10" android:layout_gravity="center" android:gravity="center" android:focusable="false" android:clickable="false"/> But anytime I press one of the checkboxes, check.isChecked() returns true, even if the box is unchecked. I even checked to make sure that the checkboxes were distinct and weren't picking up just the last value/etc. Setting up the listeners inline instead of in a method doesn't seem to help, either. It's literally just the isChecked() condition that isn't working appropriately - it seems to always give me the inverse value. Setting an onClick on the row is not acceptable in this case because I need to allow row selection for something else. What could be causing this issue?

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  • C++ : Avoid lot of boolean variable for multiple verification conditions in trading app

    - by Naveen
    Hi i am a junior dev in trading app... we have a order refresh verification unit. It has to verify order confirmation from exchange. We send a bunch of different request in bulk ( NEW, MODIFY, CANCEL ) to exchange... Verification has to happen for max N times with each T intervals for all orders. if verification successful for all the order before N retry then fine.. otherwise we need to indicate as verification unsuccessfull. i hv done a basic coding done in very urgent like below for( N times ) { for_each ( sent_request_order ) // SENT { 1) get all the refreshed order from DB or shared mem i.e REFRESHED 2) find current sent order in REFRESHED if( not_found ) not refreshed from exchange, continue to next order if( found ) case NEW : //check for new status, mark verification done case MODIFY : //check for modified status.. //if not mark pending, go to next order, //revisit the same after T time case CANCEL : //check for cancelled status.. //if not mark pending, go to next order, //revisit the same after T time } if( all_verified ) exit from verification. wait ( T sec ) } order_verification_pending, order_verification_done, order_visited, order_not_visited, all_verified, all_not_verified ... lot of boolean flags used for indication.. is there any better approach for doing this.... splitting responsibilities across the classes......???? i know this is not a general question.... but still flags are making me tidious to handle...

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  • VB.net httpwebrequest For loop hangs every 10 or so iterations

    - by user574632
    Hello, I am trying to loop through an array and perform an httpwebrequest in each iteration. The code seems to work, however it pauses for a while (eg alot longer than the set timeout. Tried setting that to 100 to check and it still pauses) after every 10 or so iterations, then carries on working. Here is what i have so far: For i As Integer = 0 To numberOfProxies - 1 Try 'create request to a proxyJudge php page using proxy Dim request As HttpWebRequest = HttpWebRequest.Create("http://www.pr0.net/deny/azenv.php") request.Proxy = New Net.WebProxy(proxies(i)) 'select the current proxie from the proxies array request.Timeout = 10000 'set timeout Dim response As HttpWebResponse = request.GetResponse() Dim sr As StreamReader = New StreamReader(response.GetResponseStream()) Dim pageSourceCode As String = sr.ReadToEnd() 'check the downloaded source for certain phrases, each identifies a type of proxy 'HTTP_X_FORWARDED_FOR identifies a transparent proxy If pageSourceCode.Contains("HTTP_X_FORWARDED_FOR") Then 'delegate method for cross thread safe UpdateListbox(ListBox3, proxies(i)) ElseIf pageSourceCode.Contains("HTTP_VIA") Then UpdateListbox(ListBox2, proxies(i)) Else UpdateListbox(ListBox1, proxies(i)) End If Catch ex As Exception 'MessageBox.Show(ex.ToString) used in testing UpdateListbox(ListBox4, proxies(i)) End Try completedProxyCheck += 1 lblTotalProxiesChecked.CustomInvoke(Sub(l) l.Text = completedProxyCheck) Next I have searched all over this site and via google, and most responses to this type of question say the response must be closed. I have tried a using block, eg: Using response As HttpWebResponse = request.GetResponse() Using sr As StreamReader = New StreamReader(response.GetResponseStream()) Dim pageSourceCode As String = sr.ReadToEnd() 'check the downloaded source for certain phrases, each identifies a type of proxy 'HTTP_X_FORWARDED_FOR identifies a transparent proxy If pageSourceCode.Contains("HTTP_X_FORWARDED_FOR") Then 'delegate method for cross thread safe UpdateListbox(ListBox3, proxies(i)) ElseIf pageSourceCode.Contains("HTTP_VIA") Then UpdateListbox(ListBox2, proxies(i)) Else UpdateListbox(ListBox1, proxies(i)) End If End Using End Using And it makes no difference (though i may have implemented it wrong) As you can tell im very new to VB or any OOP so its probably a simple problem but i cant work it out. Any suggestions or just tips on how to diagnose these types of problems would be really appreciated.

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  • Why my events aren't registered after postback?

    - by lucian.jp
    I have a problem where I have a page with a checkbox : <asp:CheckBox runat="server" ID="chkSelectAll" OnCheckedChanged="chkSelectAll_CheckedChanged" EnableViewState="true" Text='<%# CommonFunctions.GetText(Page, "CreateTask", "chkSelectAll.text") %>' AutoPostBack="true" /> First I had the problem that when the event was raised the checkbox wasn't keeping the checked property value. This is still strange because nowhere in the application we set the EnableViewState to false and by default it should be true. Well this behavior was fixed by puting EnableViewState="true". So now, I have a checkbox that when I first load the page, wworks correctly. I check the box, the event is raised Checked property valu is good and the method is executed. Postback completes and renders the page. I check the box back to false, the event is not triggered and the page is reloaded with the previous data but the Checked Property stays at true. So after the first postback I seem to loose behavior of event and ViewState. We suspect the fact that we move dynamically the controls in the page (See answer here) But this suspicion doesn't explain why everything works perfectly after the first load and stops working after first PostBack. EDIT CODE SAMPLE I created a test project where you can experience my problem. At load if you check any checkbox both raise their respective event. After postback only the second raise both events. I seem to have a problem when I register the events after moving control.

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  • Passing parameters to eventListener function

    - by bryan sammon
    I have this function check(e) that I'd like to be able to pass parameters from test() when I add it to the eventListener. Is this possible? Like say to get the mainlink variable to pass through the parameters. Is this even good to do? I put the javascript below, I also have it on jsbin: http://jsbin.com/ujahe3/9/edit function test() { if (!document.getElementById('myid')) { var mainlink = document.getElementById('mainlink'); var newElem = document.createElement('span'); mainlink.appendChild(newElem); var linkElemAttrib = document.createAttribute('id'); linkElemAttrib.value = "myid"; newElem.setAttributeNode(linkElemAttrib); var linkElem = document.createElement('a'); newElem.appendChild(linkElem); var linkElemAttrib = document.createAttribute('href'); linkElemAttrib.value = "jsbin.com"; linkElem.setAttributeNode(linkElemAttrib); var linkElemText = document.createTextNode('new click me'); linkElem.appendChild(linkElemText); if (document.addEventListener) { document.addEventListener('click', check/*(WOULD LIKE TO PASS PARAMETERS HERE)*/, false); }; }; }; function check(e) { if (document.getElementById('myid')) { if (document.getElementById('myid').parentNode === document.getElementById('mainlink')) { var target = (e && e.target) || (event && event.srcElement); var obj = document.getElementById('mainlink'); if (target!= obj) { obj.removeChild(obj.lastChild); }; }; }; };

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  • Timer Service in ejb 3.1 - schedule calling timeout problem

    - by Greg
    Hi Guys, I have created simple example with @Singleton, @Schedule and @Timeout annotations to try if they would solve my problem. The scenario is this: EJB calls 'check' function every 5 secconds, and if certain conditions are met it will create single action timer that would invoke some long running process in asynchronous fashion. (it's sort of queue implementation type of thing). It then continues to check, but as long as long running process is there it won't start another one. Below is the code I came up with, but this solution does not work, because it looks like asynchronous call I'm making is in fact blocking my @Schedule method. @Singleton @Startup public class GenerationQueue { private Logger logger = Logger.getLogger(GenerationQueue.class.getName()); private List<String> queue = new ArrayList<String>(); private boolean available = true; @Resource TimerService timerService; @Schedule(persistent=true, minute="*", second="*/5", hour="*") public void checkQueueState() { logger.log(Level.INFO,"Queue state check: "+available+" size: "+queue.size()+", "+new Date()); if (available) { timerService.createSingleActionTimer(new Date(), new TimerConfig(null, false)); } } @Timeout private void generateReport(Timer timer) { logger.info("!!--timeout invoked here "+new Date()); available = false; try { Thread.sleep(1000*60*2); // something that lasts for a bit } catch (Exception e) {} available = true; logger.info("New report generation complete"); } What am I missing here or should I try different aproach? Any ideas most welcome :) Testing with Glassfish 3.0.1 latest build - forgot to mention

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  • What's wrong with this code to un-camel-case a string?

    - by omair iqbal
    Here is my attempt to solve the About.com Delphi challenge to un-camel-case a string. unit challenge1; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls; type check = 65..90; TForm1 = class(TForm) Edit1: TEdit; Button1: TButton; procedure Button1Click(Sender: TObject); private { Private declarations } public { Public declarations } end; var Form1: TForm1; var s1,s2 :string; int : integer; implementation {$R *.dfm} procedure TForm1.Button1Click(Sender: TObject); var i: Integer; checks : set of check; begin s1 := edit1.Text; for i := 1 to 20 do begin int :=ord(s1[i]) ; if int in checks then insert(' ',s1,i-1); end; showmessage(s1); end; end. check is a set that contains capital letters so basically whenever a capital letter is encountered the insert function adds space before its encountered (inside the s1 string), but my code does nothing. ShowMessage just shows text as it was entered in Edit1. What have I done wrong?

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  • How do I create a selection list in ASP.NET MVC?

    - by Gary McGill
    I have a database table that records what publications a user is allowed to access. The table is very simple - it simply stores user ID/publication ID pairs: CREATE TABLE UserPublication (UserId INTEGER, PublicationID INTEGER) The presence of a record for a given user & publication means that the user has access; absence of a record implies no access. I want to present my admin users with a simple screen that allows them to configure which publications a user can access. I would like to show one checkbox for each of the possible publications, and check the ones that the user can currently access. The admin user can then check or un-check any number of publications and submit the form. There are various publication types, and I want to group the similarly-typed publications together - so I do need control over how the publications are presented (I don't want to just have a flat list). My view model obviously needs to have a list of all the publications (since I need to display them all regardless of the current selection), and I also need a list of the publications that the user currently has access to. (I'm not sure whether I'd be better off with a single list where each item includes the publication ID and a yes/no field?). But that's as far as I've got. I've really no idea how to go about binding this to some checkboxes. Where do I start?

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  • Nested hyperlinks in XHTML 1.1 document

    - by Nazgulled
    Hi, I'm doing a simple widget for WordPress that fetches the most recent tweets from the RSS feed provided by Twitter. This widget parses any link posted on a tweet, it also parses mentions (ie: @username) and trending topics (ie: #nowplaying). For these 3 situations, it creates links pointing to some Twitter feature. For instance: "Hi @UserA, check out the song Foo from FooBar that I'm listening, it's awesome. #nowplaying" And it will parse into this: Hi <a href="http://twitter.com/UserA">@UserA</a>, check out the song Foo from FooBar that I'm listening, it's awesome. <a href="http://twitter.com/#search?q=nowplaying">#nowplaying</a> Now now I need to add a global link to the whole message, like this: <a href="http://twitter.com/UserA/statuses/1234567890"> Hi <a href="http://twitter.com/UserA">@UserA</a>, check out the song Foo from FooBar that I'm listening, it's awesome. <a href="http://twitter.com/#search?q=nowplaying">#nowplaying</a> </a> But this code does not validate and it doesn't work anyways (the browsers don't really seem to know what to do with it). Any suggestions how could I fix this?

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  • Delphi Performance: Case Versus If

    - by Andreas Rejbrand
    I guess there might be some overlapping with previous SO questions, but I could not find a Delphi-specific question on this topic. Suppose that you want to check if an unsigned 32-bit integer variable "MyAction" is equal to any of the constants ACTION1, ACTION2, ... ACTIONn, where n is - say 1000. I guess that, besides being more elegant, case MyAction of ACTION1: {code}; ACTION2: {code}; ... ACTIONn: {code}; end; if much faster than if MyAction = ACTION1 then // code else if MyAction = ACTION2 then // code ... else if MyAction = ACTIONn then // code; I guess that the if variant takes time O(n) to complete (i.e. to find the right action) if the right action ACTIONi has a high value of i, whereas the case variant takes a lot less time (O(1)?). Am I correct that switch is much faster? Am I correct that the time required to find the right action in the switch case actually is independent of n? I.e. is it true that it does not really take any longer to check a million cases than to check 10 cases? How, exactly, does this work?

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  • 2D Platformer Collision Problems With Both Axes

    - by AusGat
    I'm working on a little 2D platformer/fighting game with C++ and SDL, and I'm having quite a bit of trouble with the collision detection. The levels are made up of an array of tiles, and I use a for loop to go through each one (I know it may not be the best way to do it, and I may need help with that too). For each side of the character, I move it one pixel in that direction and check for a collision (I also check to see if the character is moving in that direction). If there is a collision, I set the velocity to 0 and move the player to the edge of the tile. My problem is that if I check for horizontal collisions first, and the player moves vertically at more than one pixel per frame, it handles the horizontal collision and moves the character to the side of the tile even if the tile is below (or above) the character. If I handle vertical collision first, it does the same, except it does it for the horizontal axis. How can I handle collisions on both axes without having those problems? Is there any better way to handle collision than how I'm doing it?

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  • F# and statically checked union cases

    - by Johan Jonasson
    Soon me and my brother-in-arms Joel will release version 0.9 of Wing Beats. It's an internal DSL written in F#. With it you can generate XHTML. One of the sources of inspiration have been the XHTML.M module of the Ocsigen framework. I'm not used to the OCaml syntax, but I do understand XHTML.M somehow statically check if attributes and children of an element are of valid types. We have not been able to statically check the same thing in F#, and now I wonder if someone have any idea of how to do it? My first naive approach was to represent each element type in XHTML as a union case. But unfortunately you cannot statically restrict which cases are valid as parameter values, as in XHTML.M. Then I tried to use interfaces (each element type implements an interface for each valid parent) and type constraints, but I didn't manage to make it work without the use of explicit casting in a way that made the solution cumbersome to use. And it didn't feel like an elegant solution anyway. Today I've been looking at Code Contracts, but it seems to be incompatible with F# Interactive. When I hit alt + enter it freezes. Just to make my question clearer. Here is a super simple artificial example of the same problem: type Letter = | Vowel of string | Consonant of string let writeVowel = function | Vowel str -> sprintf "%s is a vowel" str I want writeVowel to only accept Vowels statically, and not as above, check it at runtime. How can we accomplish this? Does anyone have any idea? There must be a clever way of doing it. If not with union cases, maybe with interfaces? I've struggled with this, but am trapped in the box and can't think outside of it.

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  • ADO.NET Multiple simultaneous reads from an open database.

    - by Deverill
    Answer not needed - my logic was wrong and this question is invalid. Charles helped me see where I went off-tracks. Thanks I have a utility that moves data from one source to another. In the process of writing the record I check to see if it exists and do an update/insert as necessary. The difficulty I have is that as I'm writing the main record info there is a 2nd table for "custom data" that I have to check to see if it exists and do an update/insert for that as well. Example: I may be loading a pencil sharpener that may or may not exist. While I'm writing it into destination it has characteristics such as style, color, etc. and each of them may or may not exist. As written I seem to need to have 2 DataReaders open, one for the sharpener and one to check for and update color. I am new to ADO.NET, but not to programming and it's more complicated than I listed but for sanity's sake I didn't put all the details. My question is: What am I missing? You can't have 2 readers open at the same time on a connection, yet I can't close the first if I'm stepping through all products. It seems inefficient to have 2 connections, readers, etc. for this. Is there a feature of ADO.NET DBs that I'm missing? How would you do it? Thanks!

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  • Validating Time & Date To Be At Least A Certain Amount Of Time In The Future

    - by MJH
    I've built a reservation form for a taxi company which works fine, but I'm having an issue with users making reservations that are due too soon in the future. Since the entire form is kind of long, I first want to make sure the user is not trying to make a reservation for less than an hour ahead of time, without them having to fill out the whole form. This is what I have come up with so far, but it's just not working: <?php //Set local time zone. date_default_timezone_set('America/New_York'); //Get current date and time. $current_time = date('Y-m-d H:i:s'); //Set reservation time variable $res_datetime = $_POST['res_datetime']; //Set event time. $event_time = strtotime($res_datetime); ?> <!doctype html> <html> <head> <meta charset="utf-8"> <title>Check Date and Time</title> </head> <?php //Check to be sure reservation time is at least one hour in the future. if (($current_time - $event_time) <= (3600)) { echo "You must make a reservation at least one hour ahead of time."; } ?> <form name="datetime" action="" method="post"> <input name="res_datetime" type="datetime-local" id="res_datetime"> <input type="submit"> </form> <body> </body> </html> How can I create a validation check to make sure the date and time of the reservation is at least one hour ahead of time?

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  • Script to install and compile Python, Django, Virtualenv, Mercurial, Git, LessCSS, etc... on Dreamho

    - by tmslnz
    The Story After cleaning up my Dreamhost shared server's home folder from all the cruft accumulated over time, I decided to start afresh and compile/reinstall Python. All tutorials and snippets I found seemed overly simplistic, assuming (or ignoring) a bunch of dependencies needed by Python to compile all modules correctly. So, starting from http://andrew.io/weblog/2010/02/installing-python-2-6-virtualenv-and-virtualenvwrapper-on-dreamhost/ (so far the best guide I found), I decided to write a set-and-forget Bash script to automate this painful process, including along the way a bunch of other things I am planning to use. The Script I am hosting the script on http://bitbucket.org/tmslnz/python-dreamhost-batch/src/ The TODOs So far it runs fine, and does all it needs to do in about 900 seconds, giving me at the end of the process a fully functional Python / Mercurial / etc... setup without even needing to log out and back in. I though this might be of use for others too, but there are a few things that I think it's missing and I am not quite sure how to go for it, what's the best way to do it, or if this just doesn't make any sense at all. Check for errors and break Check for minor version bumps of the packages and give warnings Check for known dependencies Use arguments to install only some of the packages instead of commenting out lines Organise the code in a manner that's easy to update Optionally make the installers and compiling silent, with error logging to file failproof .bashrc modification to prevent breaking ssh logins and having to log back via FTP to fix it EDIT: The implied question is: can anyone, more bashful than me, offer general advice on the worthiness of the above points or highlight any problems they see with this approach? (see my answer to Ry4an's comment below) The Gist I am no UNIX or Bash or compiler expert, and this has been built iteratively, by trial and error. It is somehow going towards apt-get (well, 1% of it...), but since Dreamhost and others obviously cannot give root access on shared servers, this looks to me like a potentially very useful workaround; particularly so with some community work involved.

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  • What are some methods to prevent double posting in a form? (PHP)

    - by jpjp
    I want to prevent users from accidentally posting a comment twice. I use the PRG (post redirect get) method, so that I insert the data on another page then redirect the user back to the page which shows the comment. This allows users to refresh as many times as they want. However this doesn't work when the user goes back and clicks submit again or when they click submit 100 times really fast. I don't want 100 of the same comments. I looked at related questions on SO and found that a token is best. But I am having trouble using it. //makerandomtoken(20) returns a random 20 length char. <form method="post" ... > <input type="text" id="comments" name="comments" class="commentbox" /><br/> <input type="hidden" name="_token" value="<?php echo $token=makerandomtoken(20); ?>" /> <input type="submit" value="submit" name="submit" /> </form> if (isset($_POST['submit']) && !empty($comments)) { $comments= mysqli_real_escape_string($dbc,trim($_POST['comments'])); //how do I make the if-statment to check if the token has been already set once? if ( ____________){ //don't insert comment because already clicked submit } else{ //insert the comment into the database } } So I have the token as a hidden value, but how do I use that to prevent multiple clicking of submit. METHODS: someone suggested using sessions. I would set the random token to $_SESSION['_token'] and check if that session token is equal to the $_POST['_token'], but how do I do that? When I tried, it still doesn't check

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