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• How to perform different operations within Observer's update() in Java?

  - by Nazgulled

  I just started playing with Observable, Observer and it's update() method and I can't understand what should I do when different actions call notifyObservers(). I mean, my Observable class has a few different methods that call setChanged() and notifyObservers() in the end. Depending on the called method, some part of the UI (Swing) needs to be updated. However, there is only one update() method implemented in the Observer class. I though of passing something to the notifyObservers() method and then I can check the argument on update() but it doesn't seem feel like a good way to do it. Even if it did, what should I pass? A string with a short description of the action/method? And int, like an action/method code? Something else? What's the best way to handle this situation?

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• C# - calling ext. DLL function containing Delphi "variant record" parameter

  - by CaldonCZE

  Hello, In external (Delphi-created) DLL I've got the following function that I need to call from C# application. function ReadMsg(handle: longword; var Msg: TRxMsg): longword; stdcall; external 'MyDll.dll' name 'ReadMsg'; The "TRxMsg" type is variant record, defined as follows: TRxMsg = record case TypeMsg: byte of 1: (accept, mask: longword); 2: (SN: string[6]); 3: (rx_rate, tx_rate: word); 4: (rx_status, tx_status, ctl0, ctl1, rflg: byte); end; In order to call the function from C#, I declared auxiliary structure "my9Bytes" containing array of bytes and defined that it should be marshalled as 9 bytes long array (which is exactly the size of the Delphi record). private struct my9Bytes { [MarshalAs(UnmanagedType.ByValArray, ArraySubType = UnmanagedType.U1, SizeConst = 9)] public byte[] data; } Then I declared the imported "ReadMsg" function, using the "my9bytes" struct. [DllImport("MyDll.dll")] private static extern uint ReadMsg(uint handle, ref my9Bytes myMsg); I can call the function with no problem... Then I need to create structure corresponding to the original "TRxMsg" variant record and convert my auxiliary "myMsg" array into this structure. I don't know any C# equivalent of Delphi variant array, so I used inheritance and created the following classes. public abstract class TRxMsg { public byte typeMsg; } public class TRxMsgAcceptMask:TRxMsg { public uint accept, mask; //... } public class TRxMsgSN:TRxMsg { public string SN; //... } public class TRxMsgMRate:TRxMsg { public ushort rx_rate, tx_rate; //... } public class TRxMsgStatus:TRxMsg { public byte rx_status, tx_status, ctl0, ctl1, rflg; //... } Finally I create the appropriate object and initialize it with values manually converted from "myMsg" array (I used BitConverter for this). This does work fine, this solution seems to me a little too complicated, and that it should be possible to do this somehow more directly, without the auxiliary "my9bytes" structures or the inheritance and manual converting of individual values. So I'd like to ask you for a suggestions for the best way to do this. Thanks a lot!

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• Boost signals and passing class method

  - by Ockonal

  Hello, I've defined some signal: typedef boost::signals2::signal<void (int temp)> SomeSig; typedef SomeSig::slot_type SomeSigType; I have some class: class SomeClass { SomeClass() { SomeSig.connect(&SomeClass::doMethod); } void doMethod(const SomeSig &slot); }; And got a lot of errors: error: ‘BOOST_PP_ENUM_SHIFTED_PARAMS_M’ was not declared in this scope error: ‘T’ was not declared in this scope error: a function call cannot appear in a constant-expression error: a function call cannot appear in a constant-expression error: template argument 1 is invalid error: ‘BOOST_SIGNALS2_MISC_STATEMENT’ has not been declared error: expected identifier before ‘~’ token error: expected ‘)’ before ‘~’ token error: expected ‘;’ before ‘~’ token

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• Unit testing UDP socket handling code

  - by JustJeff

  Are there any 'good' ways to cause a thread waiting on a recvfrom() call to become unblocked and return with an error? The motivation for this is to write unit tests for a system which includes a unit that reads UDP datagrams. One of the branches handles errors on the recvfrom call itself. The code isn't required to distinguish between different types of errors, it just has to set a flag. I've thought of closing the socket from another thread, or do a shutdown on it, to cause recvfrom to return with an error, but this seems a bit heavy handed. I've seen mention elsewhere that sending an over-sized packet would do it, and so set up an experiment where a 16K buffer was sent to a recvfrom waiting for just 4K, but that didn't result in an error. The recvfrom just return 4096, to indicate it had gotten that many bytes.

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• Android - Looking for an AOP solution

  - by Serj Lotutovici

  I'm writing an application that on the bottom line uses it's internal API for some manipulations. The problem is that to call any method provided by that class first I (or anybody who uses the API) have to call #prepare() and after that #cleanup(). It all worked fine until the application and the API started to grow. And the risk of not calling one of the supplied methods before or after the API is now to big to be ignored (which makes it a bug risky application). Searching for a solution I found this question. I use Google Guice in my app for other purposes, but Android doesn't support AOP, that's why a use only guice-no_aop-x.jar. So I end-up with two questions: Is there an AOP solution for android to implement the same approach that is shown in the link above? Or may be someone has an idea that will be suitable for my case? Thanks in advice!

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• Categories & singelton in cocoa

  - by Nava Carmon

  Hi, I have a SingletonClass, which has only one instance. I want to expand it and add to it a category (MoreFeatures). I created a source SingletonClass+MoreFeatures, which interface/implementation looks like that: @interface SingletonClass (MoreFeatures) - (void) feature; @end @implementation SingletonClass (MoreFeatures) - (void) feature() { } @end When I created my SingletonClass i followed the Apple's example of Singleton implementation in cocoa. This singleton resides in a project B, which is a dependency of a bigger project A. I can call for [[SingletonClass sharedInstance] foo] from a source in project A and it works in case that function foo is located in SingletonClass interface/implementation. When I try to call [[SingletonClass sharedInstance] feature] from a source in project A, I get a crash, which says that there is no method feature for class SingletonClass... Why it happens? Thanks a lot, Nava EDIT: The crash happens in a runtime. The category file source resides in project B along with a SingletonClass

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• Java singleton VO class implementing serializable, having default values using getter methods

  - by user309281

  Hi All I have a J2SE application having user threads running in a separate JVM outside JBOSS server. During startup, J2SE invokes a EJB inside jboss, by passing a new object(singleton) of simple JAVA VO class having getter/setter methods. {The VO class is a singleton and implements serialiable(as mandated by EJB)}. EJB receives the object, reads all db configuration and uses the setter methods of new object to set all the values. It then returns back this updated object back to J2SE in the same remote call. After J2SE receives the object(singleton/serializable), if i invoke getter methods, I could see only default values set during object creation before EJB call, and not the values set by the EJB. Kindly throw some light on, why the received object from EJB does not see any updated values and how to rectify this. I believe it got to do with object initialization during deserialization. And i tried overriding readResolve() in the VO class, but of no help. With Regards, Krishna

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• AuthLogic perishable_token resets on every request

  - by go minimal

  In my User model I have: acts_as_authentic do |c| c.perishable_token_valid_for = 30.minutes end In my Application Controller I have the standard boilerplate code: def current_user_session return @current_user_session if defined?(@current_user_session) @current_user_session = UserSession.find end def current_user return @current_user if defined?(@current_user) @current_user = current_user_session && current_user_session.record end Now in my view I need to see if a user is logged in: <% if current_user %> Sign Out <% else %> Sign In <% end %> On every single request, current_user is being called, and that causes a SELECT call to be made to the database to find the user, then an UPDATE call that updates the last_request_at and perishable_token even though I set perishable_token_valid_for = 30.minutes. Does anyone have a better way to see if a user is logged in without causing a SELECT and UPDATE on every single page of my app. Does anyone know why the perishable token keeps updating even if I set it to be valid for 30 minutes???

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• Alternative to WhitePages API?

  - by Oscar Godson

  I'm using the WhitePages API ( developer.whitepages.com ) to get a phone type (landline or cellular) and the phone's service provider (Verizon, T-Mobile, etc), but they only have a personal API which limits you to 2 calls a second and/or 1,500 calls a day. The paid version, or "Pro", is a minimum of $500 a month and/or $0.10 a call. Does anyone know another service where I can get that information for free or cheaper than $500 / $0.10 a call? If not I'll have to try to cache everything and it'll technically be against their TOS...

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• How to organize code using an optional assembly reference?

  - by apoorv020

  I am working on a project and want to optionally use an assembly if available. This assembly is only available on WS 2008 R2, and my ideal product whould be a common binary for both computers with and without the assembly. However, I'm primarily developing on a Windows 7 machine, where I cannot install the assembly. How can I organize my code so that I can (with minimum changes) build my code on a machine without the assembly and secondly, how do I ensure that I call the assembly functions only when it is present. (NOTE : The only use of the optional assembly is to instantiate a class in the library and repeatedly call a (single) function of the class, which returns a boolean. The assembly is fsrmlib, which exposes advanced file system management operations on WS08R2.) I'm currently thinking of writing a wrapper class, which will always return true if the assembly is not present. Is this the right way to go about doing this?

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• Anyone have experience calling Rake from MSBuild for code gen and other benefits? How did it go? Wha

  - by Charlie Flowers

  While programming in C# using Visual Studio 2008, I often wish for "automatic" code generation. If possible, I'd like to achieve it by making my MSBuild solution file call out to Rake, which would call Ruby code for the code generation, having the resulting generated files automatically appear in my solution. Here's one business example (of many possible examples I could name) where this kind of automatic code generation would be helpful. In a recent project I had an interface with some properties that contained dollar amounts. I wanted a second interface and a third interface that had the same properties as the first interface, except they were "qualified" with a business unit name. Something like this: public interface IQuarterlyResults { double TotalRevenue { get; set; } double NetProfit { get; set; } } public interface IConsumerQuarterlyResults { double ConsumerTotalRevenue { get; set; } double ConsumerNetProfit { get; set; } } public interface ICorporateQuarterResults { double CorporateTotalRevenue { get; set; } double CorporateNetProfit { get; set; } } In this example, there is a "Consumer Business Unit" and a "Corporate Business Unit". Every property on IQuarterlyResults becomes a property called "Corporate" + [property name] on ICorporateQuarterlyResults, and likewise for IConsumerQuarterlyResults. Why make interfaces for these, rather than merely having an instance of IQuarterlyResults for Consumer and another instance for Corporate? Because, when working with the calculator object I was building, the user had to deal with 100's of properties, and it is much less confusing if he can deal with "fully qualified" property names such as "ConsumerNetProfit". But let's not get bogged down in this example. It is only an example and not the main question. The main question is this: I love using Ruby and ERB for code generation, and I love using Rake to manage dependencies between tasks. To solve the problem above, what I'd like to do is have MSBuild call out to Rake, and have Rake / Ruby read the list of properties on the "core" interface and then generate the code to make all the dependent interfaces and their properties. This would get triggered every time I do a build, because I'd put it into the MSBuild file for the VS.NET solution. Has anyone tried anything like this? How did it work out for you? What insights can you share about pros, cons, tips for success, etc.? Thanks!

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• CQRS - Should a Command try to create a "complex" master-detail entity?

  - by Simon Crabtree

  I've been reading Greg Young and Udi Dahan's thoughts on Command Query Responsibilty Separation and a lot of what I read strikes a chord with me. My domain (we track vehicles which are doing deliveries) has the concept of a Route which contains one or more Stops. I need my customers to be able to set these up in our system by calling a webservice, and then be able to retrieve information about a Route and how the vehicle is progressing. In the past I would have "cut-down" DTO classes which closely resemble my domain classes, and the customer would create a RouteDto with an array of StopDto(s), and call our CreateRoute webmethod, passing in the RouteDto. When they query our system by calling the GetRouteDetails method, I would return exactly the same objects to them. One of the appealing aspects of CQRS is that the RouteDto might have all manner of properties that the customer wants to query, but have no business setting when they create a Route. So I create a separate CreateRouteRequest class which is passed in when calling the CreateRoute "command", and a Route DTO class which gets returned as a query result. class Route{ string Reference; List<Stop> Stops; } But I need my customer to provide me with Route AND Stop details when they create a route. As I see it I could either... Give my CreateRouteRequest class a Stops(s) property which is an array of "something" representing the data they need to provide about each stop - but what do I call this class? It's not a Stop as that's what I'm calling the list of DTO inside my Route DTO, but I don't like "CreateStopRequest". I also wonder if I'm stuck in a CRUD mindset here thinking in terms of master-detail information and asking the customer to think like that too. class CreateRouteRequest{ string Reference; ... List<CreateStopRequest> Stops; } or They call CreateRoute, and then make a number of calls to an AddStopToRoute method. This feels a bit more "behavioural" but I'm going to lose the ability to treat creating a route including its stops as a single atomic command. If they create a Route and then try to add a Stop which fails due to some validation problem they're going to have a partially correct Route. The fact that I can't come up with a good name for the list of "StopCreationData" objects I'd be working with in option 1, makes me wonder if there's something I'm missing.

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• How do I throttle my site's API users?

  - by scotts

  The legitimate users of my site occasionally hammer the server with API requests that cause undesirable results. I want to institute a limit of no more than say one API call every 5 seconds or n calls per minute (haven't figured out the exact limit yet). I could obviously log every API call in a DB and do the calculation on every request to see if they're over the limit, but all this extra overhead on EVERY request would be defeating the purpose. What are other less resource-intensive methods I could use to institute a limit? I'm using PHP/Apache/Linux, for what it's worth.

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• NSDate & Memory management

  - by iFloh

  Hi, memory management still gives me grief. This time it is an NSDate iVar that I init using NSDate *myNSDate = [[NSDate date] firstDayOfMonth]; with a method call to - (NSDate *)firstDayOfMonth { NSDateComponents *tmpDateComponents = [[NSCalendar currentCalendar] components:NSYearCalendarUnit | NSMonthCalendarUnit | NSEraCalendarUnit | NSWeekCalendarUnit | NSWeekdayOrdinalCalendarUnit fromDate:self]; [tmpDateComponents setDay:1]; [tmpDateComponents setHour:0]; [tmpDateComponents setMinute:0]; [tmpDateComponents setSecond:0]; return [[NSCalendar currentCalendar] dateFromComponents:tmpDateComponents]; } At the end of the init call the retain count is at 1 (Note the iVar is not defined as a property). When I step into the viewWillAppear method the myNSDate has vanished. I tried to do an explicit retain on it, but that only lasts until I update the iVar using the above method again. I though - ok - I add the retain to the return of the function, but that makes the leak analyser throw up an error. What am I doing wrong?

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• [Android] accessing another Activity's preferences

  - by Raffaele

  I have a Login Activity which stores credentials in its own SharedPreferences; then I added two getters for reading them, something like public String getUsername() { return getPreferences(MODE_PRIVATE).getString("#username", null); } but this throws a NPE when I call it like this String mUser = (new Login()).getUsername(); It seems that the Activity cannot read its preferences after a simple contructor call, as if it were in some uncompleted state. I read lots of related topics, but wasn't able to find a solution. Basically, I need to share these credentials among activities in my application

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• Rails: how do you access RESTful helpers?

  - by Ethan

  I'm trying to work through this guide to Rails routing, but I got stuck in section 3.3: Creating a RESTful route will also make available a pile of helpers within your application and then they list some helpers like photos_url, photos_path, etc. My questions: Where can I find the complete list of helpers that is "made available?" Is there a way to call the helpers in the console? I created an app, then opened up the console with script/console. I tried to call one of the helpers on the console like this: >> entries_url But got: NameError: undefined local variable or method `entries_url' for #<Object:0x349a4> from (irb):8

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• How can this closure test be written in other languages?

  - by Jian Lin

  I wonder how the following closure test can be written in other languages, such as C and Java. Can the same result be expected also in Perl, Python, and PHP? Ideally, we don't need to make a new local variable such as x and assign it the value of i inside the loop, but just so that i has a new copy in the new scope each time. (if possible). (some discussion is in this question.) The following is in Ruby, the "1.8.6" on the first line of result is the Ruby version which can be ignored. p RUBY_VERSION $foo = [] (1..5).each do |i| $foo[i] = lambda { p i } end (1..5).each do |j| $foo[j].call() end the print out is: [MacBook01:~] $ ruby scope.rb "1.8.6" 1 2 3 4 5 [MacBook01:~] $ Contrast that with another test, with i defined outside: p RUBY_VERSION $foo = [] i = 0 (1..5).each do |i| $foo[i] = lambda { p i } end (1..5).each do |j| $foo[j].call() end the print out: [MacBook01:~] $ ruby scope2.rb "1.8.6" 5 5 5 5 5 [MacBook01:~] $

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• Who calls the Destructor of the class when operator delete is used in multiple inheritance.

  - by dicaprio-leonard

  This question may sound too silly, however , I don't find concrete answer any where else. With little knowledge on how late binding works and virtual keyword used in inheritance. As in the code sample, when in case of inheritance where a base class pointer pointing to a derived class object created on heap and delete operator is used to deallocate the memory , the destructor of the of the derived and base will be called in order only when the base destructor is declared virtual function. Now my question is : 1) When the destructor of base is not virtual, why the problem of not calling derived dtor occur only when in case of using "delete" operator , why not in the case given below: derived drvd; base *bPtr; bPtr = &drvd; //DTOR called in proper order when goes out of scope. 2) When "delete" operator is used, who is reponsible to call the destructor of the class? The operator delete will have an implementation to call the DTOR ? or complier writes some extra stuff ? If the operator has the implementation then how does it looks like , [I need sample code how this would have been implemented]. 3) If virtual keyword is used in this example, how does operator delete now know which DTOR to call? Fundamentaly i want to know who calls the dtor of the class when delete is used. Sample Code class base { public: base() { cout<<"Base CTOR called"<<endl; } virtual ~base() { cout<<"Base DTOR called"<<endl; } }; class derived:public base { public: derived() { cout<<"Derived CTOR called"<<endl; } ~derived() { cout<<"Derived DTOR called"<<endl; } }; I'm not sure if this is a duplicate, I couldn't find in search. int main() { base *bPtr = new derived(); delete bPtr;// only when you explicitly try to delete an object return 0; }

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• Starting new transaction within existing one in Spring bean

  - by Marcus

  We have: @Transactional(propagation = Propagation.REQUIRED) public class MyClass implementes MyInterface { ... MyInterface has a single method: go(). When go() executes we start a new transaction which commits/rollbacks when the method is complete - this is fine. Now let's say in go() we call a private method in MyClass that has @Transactional(propagation = Propagation.REQUIRES_NEW. It seems that Spring "ignores" the REQUIRES_NEW annotation and does not start a new transaction. I believe this is because Spring AOP operates on the interface level (MyInterface) and does not intercept any calls to MyClass methods. Is this correct? Is there any way to start a new transaction within the go() transaction? Is the only way to call another Spring managed bean that has transactions configured as REQUIRES_NEW?

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• Solr dataimport skips entities in my data-config.xml

  - by lerhaupt

  My data-config.xml defines 3 different entities under the document tag (lets call them foo, bar and baz). When I issue a basic full import localhost:8983/solr/dataimport?command=full-import, only 2 of the 3 entities get indexed (foo and bar are in my index but baz never makes it). However, if I then issue a command to just import baz via localhost:8983/solr/dataimport?command=full-import&entity=baz&clean=false it adds baz documents just fine and the index then has all 3 types. Does anyone have any thoughts on why one entity gets skipped in the general data import but then still works okay if I specifically call it out? Is there an error/warning log I can check? Nothing bad shows up in /solr/logs/ but those just appear to be request logs.

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• Returning the value of an identity column during/after SQL INSERT command

  - by Adam Kane

  Using VS 2010, with ASP.NET, and .NET 3.0, and C#... When I use a System.Web.UI.WebControls.SqlDataSource and call its Insert() method to insert a new row, and that table has an identity column, I'd like my method to return the value of that column. For example, in my SQL 2005 table, I've got: Customer.Id Customer.FirstName Customer.LastName Where Customer.Id is an identity colum. When I call my method InsertNewCustomerRecord( "John", "Smith" ), I'd like to be able to return the Customer.Id that gets automatically generated in the database. Sorry for such a roughly posed question. Let me know if I can add better detail. Thanks.

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• Passing parameters to a JQuery function.

  - by jmpena

  Hello, ive a problem using JQuery.. Im creating a HTML with a loop and it has a column for Action, that column is a HyperLink that when the user click the link call a JavaScript function and pass the parameters... example: <a href="#" OnClick="DoAction(1,'Jose');" > Click </a> <a href="#" OnClick="DoAction(2,'Juan');" > Click </a> <a href="#" OnClick="DoAction(3,'Pedro');" > Click </a> ... <a href="#" OnClick="DoAction(n,'xxx');" > Click </a> i want that function to Call an Ajax JQuery function with the correct parameters. any help ??

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• Synclock a section of code while waiting for ShowDialog to return

  - by clawson

  I'm having trouble working out how to lock my application out of a section of code while it waits for a response from an external program. I've used Synclock on a section of code with the Me object in the expression. In this Synclock I call an overridden ShowDialog method of a dialog box, which has a timeout parameter, but does return the value from the underlying ShowDialog function call ,once the timer is setup. Works like this. SyncLock Me Dim frmDlgWithTimeout As New frmDlgWithTimeout ' dialog box with overridden ShowDialog ' Dim res As DialogResult = frmDlgWithTimeout.ShowDialog(10 * 1000) ' 10 sec timeout ' End SyncLock Now, external programs may raise events that bring my application to this Synclock but it doesn't prevent it from entering it, even though the ShowDialog function hasn't returned a value (and hence what I thought would keep the section of code locked). There is only one instance of the object that is used for lock in the program. Your help is greatly appreciated.

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• Why is my Extension Method not showing up in my test class?

  - by Robert Harvey

  I created an extension method called HasContentPermission on the System.Security.Principal.IIdentity interface: namespace System.Security.Principal { public static bool HasContentPermission (this IIdentity itentity, int contentID) { // I do stuff here return result; } } And I call it like this: bool hasPermission = User.Identity.HasPermission(contentID); Works like a charm. Now I want to unit test it. To do that, all I really need to do is call the extension method directly, so: using System.Security.Principal; namespace MyUnitTests { [TestMethod] public void HasContentPermission_PermissionRecordExists_ReturnsTrue() { IIdentity identity; bool result = identity.HasContentPermission(... But HasContentPermission won't intellisense. I tried creating a stub class that inherits from IIdentity, but that didn't work either. Why? Or am I going about this the wrong way?

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• List of private iPhone APIs?

  - by diego nunes

  . . Hi there, everybody. . . I need to do an app to be distributed ad hoc (it doesn't need to go to the store) but I need to get the information about the "data usage" (gprs/3g traffic). It is available on the system, but there is no official API call to get that info. One app made it through Apple testing (it's called "Download Meter"), though, and I emailed the guys to see if they would share the call, but they were not in that mood. . . Is there any list of private APIs or anything like that? Does anyone have any ideas of how could I get that info? Again: the app doesn't need to go to the store, but I need to install it on stock iPhone (ad hoc will do). . Thanks.

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