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  • C++ STL 101: Overload function causes build error

    - by Sidjal
    Trivial code that works if I do not overload myfunc. void myfunc(int i) { std::cout << "calling myfunc with arg " << i << std::endl; } void myfunc(std::string s) { std::cout << "calling myfunc with arg " << s << std::endl; } void testalgos() { std::vector<int> v; v.push_back(1); v.push_back(2); std::vector<std::string> s; s.push_back("one"); s.push_back("two"); std::for_each( v.begin(), v.end(), myfunc); std::for_each( s.begin(), s.end(), myfunc); return; } int _tmain(int argc, _TCHAR* argv[]) { std::cout << "Hello World" << std::endl; testalgos(); return 0; } The following build errors repeat for both for_each calls. error C2914: 'std::for_each' : cannot deduce template argument as function argument is ambiguous error C2784: '_Fn1 std::for_each(_InIt,_InIt,_Fn1)' : could not deduce template argument for '_InIt' from 'std::_Vector_iterator<_Ty,_Alloc'. It does work if I do not overload myfunc.Can someone explain what is happening here. TIA

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  • please help me to solve problem

    - by davit-datuashvili
    first of all this is not homework and nobody tag it as homewrok i did not understand this porblem can anybody explain me?this is not english problem it is just misunderstanding what problem say Consider the problem of neatly printing a paragraph on a printer. The input text is a sequence of n words of lengths l1 , l2 , . . . , ln , measured in characters. We want to print this paragraph neatly on a number of lines that hold a maximum of M characters each. Our criterion of “neatness” is as follows. If a given line contains words i through j , where i = j , and we leave exactly one space between words, the number of extra space characters at the end of the line is M - j + i -(k=i,k< j,k++) lk , which must be nonnegative so that the words fit on the line. We wish to minimize the sum, over all lines except the last, of the cubes of the numbers of extra space characters at the ends of lines. Give a dynamic-programming algorithm to print a paragraph of n words neatly on a printer. Analyze the running time and space requirements of your algorithm.

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  • Checking Selected Radio Button after POST

    - by coffeeaddict
    I've been using ASP.NET controls which perform a lot of the manual for you. But I'm going back to the basics, what everyone else does. I'm using standard input tags. So for example if I have a radio button group and I select a button. When the form submits and does a POST back to whatever action="MyPage.aspx" then to grab and check the radio button's value that was selected is it always done like this below? <label><input type="radio" name="rbGroup" value='<%# ((Action)Container.DataItem).ID %>'/><%# ((Action)Container.DataItem).Name %></label> So here I'm appending the ID to the value. And then when it hits the page that my action specifies, I'm checking to see which was selected by trimming off and getting that ID from the value: string selection = Request.Form["rbGroup"]; string dbRecordIdSelected = int.Parse(selection.Substring(1)); so now I can check the id they selected...that is the ID of the db record that gave that selected radio it's name. Is that how you basically always check what radio was selected by checking the name/value pair that comes across for that selected radioButton group name? And then you can append stuff like IDs or whatever you want to grab and parse out to then do additional logic on the server-side once that header reaches the server and your specified page in the action attribute? The above code is not production code, just something to explain what I'm talking about.

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  • Global State and Singletons Dependency injection

    - by Manu
    this is a problem i face lot of times when i am designing a new app i'll use a sample problem to explain this think i am writing simple game.so i want to hold a list of players. i have few options.. 1.use a static field in some class private static ArrayList<Player> players = new ArrayList<Integer>(); public Player getPlayer(int i){ return players.get(i); } but this a global state 2.or i can use a singleton class PlayerList{ private PlayerList instance; private PlayerList(){...} public PlayerList getInstance() { if(instance==null){ ... } return instance; } } but this is bad because it's a singleton 3.Dependency injection class Game { private PlayerList playerList; public Game(PlayerList list) { this.list = list; } public PlayerList getPlayerList() { return playerList; } } this seems good but it's not, if any object outside Game need to look at PlayerList (which is the usual case) i have to use one of the above methods to make the Game class available globally. so I just add another layer to the problem. didn't actually solve anything. what is the optimum solution ? (currently i use Singleton approach)

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  • PHP: Adding arrays together

    - by Svish
    Could someone help me explain this? I have two snippets of code, one works as I expect, but the other does not. This works $a = array('a' => 1, 'b' => 2); $b = array('c' => 3); $c = $a + $b; print_r($c); // Output Array ( [a] => 1 [b] => 2 [c] => 3 ) This does not $a = array('a', 'b'); $b = array('c'); $c = $a + $b; print_r($c); // Output Array ( [a] => 1 [b] => 2 ) What is going on here?? Why doesn't the second version also add the two arrays together? What have I misunderstood? What should I be doing instead? Or is it a bug in PHP?

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  • Session in php are not enough clear to me

    - by Lulzim
    I find sessions in php kind of confusing, can anybody of you explain those to me. I have an example which is not working in my case: I register sessions this way, would you please tell me is this the right way of registering sessions //this is the page from where i register myusername in sessions if($count==1){ session_start(); $_SESSION['myusername'] = $_POST['myusername']; include("enterpincover.php"); } else { echo "Wrong Pin"; } here i check first whether the username is registered in sessions in oder to open his account , otherwise open again login. It works, if user is not loged in, it will show login page which is right, if user is loged it shows welcome message but not the Welcome the name of the user as I want. for ex: Welcome David <?php session_start(); if(isset($_SESSION['myusername'])) { echo 'Welcome '.$_SESSION['myusername']; } else { include("leftmodules.php"); include("rightmodules.php"); include("login.php"); } ?>

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  • Strange behavior when overloading methods in Java

    - by Sep
    I came across this weird (in my opinion) behavior today. Take this simple Test class: public class Test { public static void main(String[] args) { Test t = new Test(); t.run(); } private void run() { List<Object> list = new ArrayList<Object>(); list.add(new Object()); list.add(new Object()); method(list); } public void method(Object o) { System.out.println("Object"); } public void method(List<Object> o) { System.out.println("List of Objects"); } } It behaves the way you expect, printing "List of Objects". But if you change the following three lines: List<String> list = new ArrayList<String>(); list.add(""); list.add(""); you will get "Object" instead. I tried this a few other ways and got the same result. Is this a bug or is it a normal behavior? And if it is normal, can someone explain why? Thanks.

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  • Is there a selector or a work around to select any element with no children.

    - by rnaud
    Looking at the CSS3 specs, I can't find any way to select any element that has no children. Let me explain. <body> <h1>Main Page</h1> <div id="main"> <div class="post"> <h2>Article 1</h1> <p>some text</p> </div> <div class="post"> <h2>Article 2</h1> <p>some text</p> </div> </div> </body> I'm looking for a CSS syntax to select the h1, the two h2 and the two p. A way to select in any page, all elements with no children. Any suggestion ? Sorry, I forgot to add the "empty" part, I am actually already using the *:empty selector, but it's not working for any tag that has a nodeText as a child. So it's working for any input, image, object, but not for h2, h1, or any p.

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  • Bizarre static_cast trick?

    - by Rob
    While perusing the Qt source code I came across this gem: template <class T> inline T qgraphicsitem_cast(const QGraphicsItem *item) { return int(static_cast<T>(0)->Type) == int(QGraphicsItem::Type) || (item && int(static_cast<T>(0)->Type) == item->type()) ? static_cast<T>(item) : 0; } Notice the static_cast<T>(0)->Type? I've been using C++ for many years but have never seen 0 being used in a static_cast before. What is this code doing and is it safe? Background: If you derive from QGraphicsItem you are meant to declare an unique enum value called Type that and implement a virtual function called type that returns it, e.g.: class Item : public QGraphicsItem { public: enum { Type = MAGIC_NUMBER }; int type() const { return Type; } ... }; You can then do this: QGraphicsItem* item = new Item; ... Item* derivedItem = qgraphicsitem_cast<Item*>(item); This will probably help explain what that static_cast is trying to do.

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  • Simple javascript/jquery append, remove question

    - by Scarface
    Hey guys, quick question. I have a div that on click will execute a jquery function onclick, and then replace the div with its opposite div which onclick will replace back to the first div just like the favorite function on this site. I am having a simple problem I hope someone can spot or explain to me it is not possible. The function works with the initial two divs that are served directly, but when I click on either of the original two divs, and the function executes and replaces the div with the corresponding div the replacement div does not execute the function. I have to refresh the page to get the original div, which is identical to execute the function. Is the div actually replaced on the page with append, or does it just visually show it? Any advice appreciated. original div <div class="unfavorite"><img id="unfavorite_img" src="images/favorite2.png" /></div> javascript div replacement $(".favorite").remove(); $(".favoriteholder").append('<div class="unfavorite"><img id="unfavorite_img" src="images/favorite2.png" /></div>');

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  • Big-Oh running time of code in Java (are my answers accurate

    - by Terry Frederick
    the Method hasTwoTrueValues returns true if at least two values in an array of booleans are true. Provide the Big-Oh running time for all three implementations proposed. // Version 1 public boolean has TwoTrueValues( boolean [ ] arr ) { int count = 0; for( int i = 0; i < arr. length; i++ ) if( arr[ i ] ) count++; return count >= 2; } // Version 2 public boolean hasTwoTrueValues( boolean [ ] arr ) { for( int i = 0; i < arr.length; i++ ) for( int j = i + 1; j < arr.length; j++ ) if( arr[ i ] && arr[ j ] ) return true; } // Version 3 public boolean hasTwoTrueValues( boolean [ ] arr ) { for( int i = 0; i < arr.length; i++ if( arr[ i ] ) for( int j = i + 1; j < arr.length; j++ ) if( arr[ j ] ) return true; return false; } For Version 1 I say the running time is O(n) Version 2 I say O(n^2) Version 3 I say O(n^2) I am really new to this Big Oh Notation so if my answers are incorrect could you please explain and help.

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  • Nested modal view controller gives strange message under iOS6?

    - by user1840362
    I am presenting a modal view controller from another modal view controller, and this worked fine under all iOS versions prior to iOS6. But under iOS6 I am getting the following warning message in the emulator: Warning: Attempt to present <UINavigationController: 0x14e93680> on <UINavigationController: 0x9fc6b70> while a presentation is in progress! The modal view controller is not shown if this warning appears. Basically I am using code like this to show the modal view controller: WebAuthViewController *authController = [[WebAuthViewController alloc] initWithNibName:nil bundle:nil]; authController.challenge = challenge; authController.delegate = self; UINavigationController *aNavController = [[UINavigationController alloc] initWithRootViewController:authController]; [self presentModalViewController:aNavController animated:YES]; [aNavController release]; [authController release]; The view that is already shown is a UIWebView also shown in a modal view, like this: WebViewController *addController = [[WebViewController alloc] initWithNibName:nil bundle:nil]; addController.urlToLoad = [NSURL URLWithString:urlString]; addController.delegate = self; UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:addController]; navigationController.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal; [self presentModalViewController:navigationController animated:YES]; [navigationController release]; [addController release]; The apple docs still suggest that one is supposed to be able to stack navigation controllers like this, so I am at a loss to explain why this happens. Any hints?

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  • an error "has no member named"

    - by helloWorld
    I have this snippet of the code account.cpp #include "account.h" #include <iostream> #include <string> using namespace std; Account::Account(string firstName, string lastName, int id) : strFirstName(firstName), strLastName(lastName), nID(id) {} void Account::printAccount(){ cout << strFirstName; } account.h #include <string> using std::string; class Account{ private: string strLastName; //Client's last name string strFirstName; //Client's first name int nID; //Client's ID number int nLines; //Number of lines related to account double lastBill; public: Account(string firstName, string lastName, int id); void printAccount(); }; company.h #ifndef CELLULAR_COMPANY_H #define CELLULAR_COMPANY_H #include <string> #include <list> #include <iostream> #include "account.h" using namespace std; class Company { private: list<Account> listOfAccounts; public: void addAccount(string firstName, string lastName, int id) { Account newAccount(firstName, lastName, id); listOfAccounts.push_back(newAccount); } void printAccounts(){ for(list<Account>::iterator i = listOfAccounts.begin(); i != listOfAccounts.end(); ++i){ i.printAccount; //here bug } } }; #endif // CELLULAR_COMPANY_H main.cpp #include "cellularcompany.h" int main(){ Company newCompany; newCompany.addAccount("Pavel", "Nedved", 11111); newCompany.printAccounts(); return 0; } can somebody please explain what does my error mean? thanks in advance (I have it in company.h see comment there) I have bug 'struct std::_List_iterator<Account>' has no member named 'printAccount'

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  • jQuery .ready() automatically assigning variables for each element with ID in DOM

    - by Greg
    I have noticed some unexpected behaviour when using the jQuery .ready() function, whereby afterwards you can reference an element in the DOM simply by using its ID without prior declaration or assignment: <html> <script src="jquery.js"></script> <script> $(document).ready(function() { myowndiv.innerHTML = 'wow!' }); </script> <body> <div id="myowndiv"></div> </body> </html> I would have expected to have to declare and assign myowndiv with document.getElementById("myowndiv"); or $("#myowndiv"); before I could call innerHTML or anything else on it? Is this behaviour by design? Can anyone explain why? My fear is that if I refactor and end up not using .ready() or even using jQuery at all then my code will fail to execute. Cheers!

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  • c# Find value in a range using lambda

    - by n4rzul
    I'm trying to find an item in a list of values based on another value using a lambda expression using the Find method. In this example I'm expecting to get back -1000, but for the life of me, I just can't come up with the proper lamda expression. If that sounds confusing I hope the code and comments below explain it better. TIA. using System; using System.Collections.Generic; namespace TestingStuff { class Program { static void Main(string[] args) { double amount = -200; //The Range of values List<MyValue> values = new List<MyValue>(); values.Add(new MyValue(-1000)); values.Add(new MyValue(-100)); values.Add(new MyValue(-10)); values.Add(new MyValue(0)); values.Add(new MyValue(100)); values.Add(new MyValue(1000)); //Find it!!! MyValue fVal = values.Find(x => (x.Value > amount) && (x.Value < amount)); //Expecting -1000 as a result here since -200 falls between -1000 and -100 //if it were -90 I'd expect -100 since it falls between -100 and 0 if (fVal != null) Console.WriteLine(fVal.Value); Console.ReadKey(); } } public class MyValue { public double Value { get; set; } public MyValue(double value) { Value = value; } } }

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  • Why doesn't sed's automatic printing deliver the expected results?

    - by CodeGnome
    What Works This sed script works as intended: $ echo -e "2\n1\n4\n3" | sed -n 'h; n; G; p' 1 2 3 4 It takes pair of input lines at a time, and swaps the lines. So far, so good. What Doesn't Work What I don't understand is why I can't use sed's automatic printing. Since sed automatically prints the pattern space at the end of each execution cycle (except when it's suppressed), why is this not equivalent? $ echo -e "2\n1\n4\n3" | sed 'h; n; G' 2 1 2 4 3 4 What I think the code says is: The input line is copied to the hold space. The next line is read into the pattern space. The hold space is appended to the pattern space. The pattern space (line1 + newline + line2) is printed automatically because we've reached the end of the execution cycle. Obviously, I'm wrong...but I don't understand why. Can anyone explain why this second example breaks, and why print suppression is needed to yield the correct results?

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  • Database tables with dynamic information

    - by Tim Fennis
    I've googled this and found that it's almost impossible to create a database with dynamic collumns. I'll explain my problem first. I am making a webshop for a customer. It has multiple computer products for sale. CPU's HDD's RAM ect. All these products have different properties, a CPU has an FSB, RAM has a CAS latency. But this is very inconvenient because my orders table needs foreign keys to different tables which is impossible. An other option is to store all the product specific information in a varchar or blob field and let PHP figure it out. The problem with this solution is that the website needs a PC builder. A step-by-step guide to building your PC. So for instance if a customer decides he wants a new "i7 920" or whatever i want to be able to sellect all motherboards for socket 1366, which is impossible because all the data is stored in one field. I know it's possible to select all motherboards form the DB and let PHP figure out which ones are for socket 1366 but i was wondering, is there a better solution?

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  • Memcached getDelayed alternative implementation

    - by iBobo
    I would like to use getDelayed on the PHP Memcached extension but I think it's not implemented in the right way. Right now you ask for some keys and then retrieve all of them with fetch() and fetchAll(). But imagine a scenario where I need to retrieve 15 keys used in different parts of the page which I don't know in advance, but I can ask the various objects to give me the list. What I want is give the Memcached instance this list (each component would give its part) then later when I need them retrieve from the instance, but not all of them at once: each component would take the one it needs. Basically if I were to implement this I would prohibit using getDelayed alone and implement a bookGet($keys) method where you would add the keys to book (which actually calls getDelayed), and redefine get to handle these three cases: key is booked and retrieved - return the value; key is booked but not retrieved - go and force the fetch of the booked keys and return the correct value; key not booked - do a normal lookup. I want to know if this makes sense, your thoughts on the subject and if someone already implemented this or maybe PECL Memcached already works this way and actually the documentation doesn't explain it correctly.

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  • how to fetch data using jquery

    - by user3566029
    I have tried to connect my index.php file in 000webhost.com using jQuery. From the site menu I have connected with 000webhost using FTP details available in 000webhost.com. When I tried to read data from jQuery it doesn’t working. Anyone please tell me what should I need to change? Should I need to connect my Dreamweaver database to webhost? If yes please explain? This is what I have done. index.php $mysql_host = "mysql0.000webhost.com"; $mysql_database = "a000000_mydb"; $mysql_user = "a000000_root"; $mysql_password = "******"; $conn=@mysql_connect ( $mysql_host,$mysql_user,$mysql_password )or die('aa'); mysql_select_db($mysql_database,$conn) or die('eoor on db'); $quer=mysql_query("SELECT * FROM sam"); $res=array(); while($row=mysql_fetch_row($quer)) { $res[]=$row; } print(json_encode($res)); return json_encode($res); mysql_close(); index.html $.get('public_html/index.php', function( data ) { alert( 'Successful' +data); });

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  • how to make custom ROMs for lesser-known Android devices (i.e., WellcoM A69)

    - by gonzobrains
    Hi, I have a WellcoM A69 Android phone I would like to start hacking. I bought it in Thailand (I think WellcoM is a Thai company). However, the docs don't explain how to get a recovery menu or anything like that. I would like to figure out how to make custom ROMs for it, because it doesn't have any Google Experience apps and I also want to change the boot screen. How can I go about doing this? If I can't do this, I want to at least be able to use the device in the Eclipse debugger. I select the debugging option under applications but the device still isn't recognized. Is this something that can be disabled by the manufacturer? In any case, I would like to re-enable it if a custom ROM can allow this. If this cannot be done at all, please at least point me in the direction of where I can start writing/building my own ROMs for the G1? I figured that would be a good starting point for learning. Thanks, Jeff

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  • PHP: Need a double check on an error in this small code

    - by Josh K
    I have this simple Select box that is suppose to store the selected value in a hidden input, which can then be used for POST (I am doing it this way to use data from disabled drop down menus) <body> <?php $Z = $_POST[hdn]; ?> <form id="form1" name="form1" method="post" action="test.php"> <select name="whatever" id="whatever" onchange="document.getElementById('hdn').value = this.value"> <option value="1">1Value</option> <option value="2">2Value</option> <option value="3">3Value</option> <option value="4">4Value</option> </select> <input type="hidden" name ='hdn' id="hdn" /> <input type="submit" id='submit' /> <?php echo "<p>".$Z."</p>"; ?> </form> </body> The echo call works for the last 3 options (2,3,4) but if I select the first one it doesnt output anything, and even if i change first one it still doesnt output anything. Can someone explain to me whats going on, I think it might be a syntax issue.

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  • Required attribute HTML5

    - by Joop
    First of all I will explain how I stumbled into this behavior. Within my web application I am using some custom validation for my form fields. Within the same form I have two buttons. One to actually submit the form and the other to cancel/reset the form. Mostly I use Safari as my default browser. Now Safari 5 is out and suddenly my cancel/reset button didn't work anymore. Every time I did hit the reset button the first field in my form did get the focus. However this is the same behavior as my custom form validation. When trying it with another browser everything just worked fine. I had to be a Safari 5 problem. I changed a bit in my Javascript code and I found out that the following line was causing the problem: document.getElementById("somefield").required = true; To be sure that would be really the problem I created a test scenario: <!DOCTYPE html> <html> <head> <title>Test</title> </head> <body> <form id="someform"> <label>Name:</label>&nbsp;<input type="text" id="name" required="true" /><br/> <label>Car:</label>&nbsp;<input type="text" id="car" required="true" /><br/> <br/> <input type="submit" id="btnsubmit" value="Submit!" /> </form> </body> </html> What I expected would happen did happen. The first field "name" did get the focus automatically. Anyone else stumbled into this?

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  • Dojo's nested BorderContainer disappear in IE

    - by h4b0
    I have this terrible problem with IE 7/8/9. I wrote an app using Dojo toolkit 1.8.0 and Play! framework. It works fine in all browser except for IE. Its 'developers tools' show no error, so does firebug. The problematic code section is here: <div data-dojo-type="dijit.layout.BorderContainer" data-dojo-props="design: 'headline'"> <div data-dojo-type="dijit.layout.ContentPane" id="head" region="top"> </div> <div data-dojo-type="dijit.layout.BorderContainer" data-dojo-props="region: 'center'"> <div data-dojo-type="dijit.layout.ContentPane" id="menu" region="left"> </div> <div data-dojo-type="dijit.layout.BorderContainer" data-dojo-props="region: 'center'"> <div data-dojo-type="dijit.layout.ContentPane" id="content_1" region="top"> </div> <div data-dojo-type="dijit.layout.ContentPane" id="content_2" region="bottom"> </div> </div> </div> <div data-dojo-type="dijit.layout.ContentPane" id="foot" region="bottom"> </div> </div> The result, in all browsers except for IE is like that: But in IE it is shown like that: Can anyone explain why there are such differences? At first I thought that in IE content is hidden, so I set overflow: auto, but no scrollbar appeared after page load.

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  • Why is Attributes.IsDefined() missing overloads?

    - by Hans Passant
    Inspired by an SO question. The Attribute class has several overloads for the IsDefined() method. Covered are attributes applied to Assembly, Module, MemberInfo, ParameterInfo. The MemberInfo overload covers PropertyInfo, FieldInfo, EventInfo, MethodInfo, ConstructorInfo. That takes care of most of the AttributeTargets. Except for one biggy: there is no overload for Attribute.IsDefined(Type, Type) so that you could check if an attribute is defined on a class. Or a struct, delegate or enum for that matter. Not that this is a real problem, Type.GetCustomAttributes() can fix that. But all of the BlahInfo types have this too. I wonder at the lack of symmetry. I can't put a finger on why this would be problem for Type. Guessing at an inheritance problem doesn't explain it to me. Having ValueType in the mix might be a lead, still doesn't make sense. I don't buy "they forgot", they never do. Why is this overload missing?

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  • How to set the ActiveMQ redeliveryPolicy on a queue?

    - by edbras
    How do I set the redeliveryPolicy in ActiveMQ on a Queue? 1) In the doc, see: activeMQ Redelivery, the explain that you should set it on the ConnectionFactory or Connection. But I want to use different value's for different Queue's. 2) Apart from that, I don't seem to get it work. Setting it on the connection factory in Spring (I am using activemq 5.4.2. with Spring 3.0) like this don't seem to have any effect: <amq:connectionFactory id="amqConnectionFactory" brokerURL="${jms.factory.url}" > <amq:properties> <amq:redeliveryPolicy maximumRedeliveries="6" initialRedeliveryDelay="15000" useExponentialBackOff="true" backOffMultiplier="5"/> </amq:properties> </amq:connectionFactory> I also tried to set it as property on the defined Queue, but that also seem to be ignored as the redelivery occurs sooner that the defined values: <amq:queue id="jmsQueueDeclarationSnd" physicalName="${jms.queue.declaration.snd}" > <amq:properties> <amq:redeliveryPolicy maximumRedeliveries="6" initialRedeliveryDelay="15000" useExponentialBackOff="true" backOffMultiplier="5"/> </amq:properties> </amq:queue> Thanks

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