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  • MinGW/GCC Delay Loaded DLL equivalent?

    - by VoiDeD
    Hello, I'm trying to port some old MSVC C++ code to MinGW/GCC. One problem is that the project relies heavily on the /DELAYLOAD option for functions that aren't always used, and where the proper dll is located at runtime. Is there such a similar option on MinGW/GCC? This code is targeting the windows platform.

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  • Creating/Maintaining a large project-agnostic code library

    - by bufferz
    In order to reduce repetition and streamline testing/debugging, I'm trying to find the best way to develop a group of libraries that many projects can utilize. I'd like to keep individual executable relatively small, and have shared libraries for math, database, collections, graphics, etc. that were previously scattered among several projects and in many cases duplicated (bad!). This library is to be in an SVN repo and several programmers will be working on it. This library will be in constant development along with the executables that utilize it. For example, I want a code file in ProjectA to look something like the following: using MyCompany.Math.2D; //static 2D math methods using MyCompany.Math.3D; //static #D math methods using MyCompany.Comms.SQL; //static methods for doing simple SQLDB I/O using MyCompany.Graphics.BitmapOperations; //static methods that play with bitmaps So in my ProjectA solution file in VisualStudio, in order to develop/debug the MyCompany library I have to add several projects (Math, Comms, Graphics). Things get pretty cluttered and Solution files get out of date quickly between programmer SVN commits. I'm just looking for a high level approach to maintaining a large, shared code base in an SCN repository. I am fully willing to radically redesign my approach. I'm looking for that warm fuzzy feeling you get when you're design approach is spot on and development is fluid and natural. And ideas? Thanks!!

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  • An interesting case of delete and destructor (C++)

    - by Viet
    I have a piece of code where I can call destructor multiple times and access member functions even the destructor was called with member variables' values preserved. I was still able to access member functions after I called delete but the member variables were nullified (all to 0). And I can't double delete. Please kindly explain this. Thanks. #include <iostream> using namespace std; template <typename T> void destroy(T* ptr) { ptr->~T(); } class Testing { public: Testing() : test(20) { } ~Testing() { printf("Testing is being killed!\n"); } int getTest() const { return test; } private: int test; }; int main() { Testing *t = new Testing(); cout << "t->getTest() = " << t->getTest() << endl; destroy(t); cout << "t->getTest() = " << t->getTest() << endl; t->~Testing(); cout << "t->getTest() = " << t->getTest() << endl; delete t; cout << "t->getTest() = " << t->getTest() << endl; destroy(t); cout << "t->getTest() = " << t->getTest() << endl; t->~Testing(); cout << "t->getTest() = " << t->getTest() << endl; //delete t; // <======== Don't do it! Double free/delete! cout << "t->getTest() = " << t->getTest() << endl; return 0; }

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  • How can I extend this SQL query to find the k nearest neighbors?

    - by Smigs
    I have a database full of two-dimensional data - points on a map. Each record has a field of the geometry type. What I need to be able to do is pass a point to a stored procedure which returns the k nearest points (k would also be passed to the sproc, but that's easy). I've found a query at http://blogs.msdn.com/isaac/archive/2008/10/23/nearest-neighbors.aspx which gets the single nearest neighbour, but I can't figure how to extend it to find the k nearest neighbours. This is the current query - T is the table, g is the geometry field, @x is the point to search around, Numbers is a table with integers 1 to n: DECLARE @start FLOAT = 1000; WITH NearestPoints AS ( SELECT TOP(1) WITH TIES *, T.g.STDistance(@x) AS dist FROM Numbers JOIN T WITH(INDEX(spatial_index)) ON T.g.STDistance(@x) < @start*POWER(2,Numbers.n) ORDER BY n ) SELECT TOP(1) * FROM NearestPoints ORDER BY n, dist The inner query selects the nearest non-empty region and the outer query then selects the top result from that region; the outer query can easily be changed to (e.g.) SELECT TOP(20), but if the nearest region only contains one result, you're stuck with that. I figure I probably need to recursively search for the first region containing k records, but without using a table variable (which would cause maintenance problems as you have to create the table structure and it's liable to change - there're lots of fields), I can't see how.

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  • Design pattern to keep track UITableView rows correspondance to underlying data in constant time.

    - by DenNukem
    When my model changes I want to animate changes in UITableView by inserting/deleting rows. For that I need to know the ordinal of the given row (so I can construct NSIndexPath), which I find hard to do in better-than-linear time. For example, consider that I have a list of addressbook entries which are manualy sorted by the user, i.e. there is no ordering "key" that represents the sort order. There is also a corresponding UITableView that shows one row per addressbook entry. When UITableView queries the datasource I query the NSMUtableArray populated with my entries and return required data in constant time for each row. However, if there is a change in underlying model I am getting a notification "Joe Smith, id#123 has been removed". Now I have a dilemma. A naive approach would be to scan the array, determine the index at which Joe Smith is and then ask UITableView to remove that precise row from the view, also removing it form the array. However, the scan will take linear time to finish. Now I could have an NSDictionary which allows me to find Joe Smith in constant time, but that doesn't do me a lot of good because I still need to find his ordinal index within the array in order to instruct UITableView to remove that row, which is again a linear search. I could further decide to store each object's ordinal inside the object itself to make it constant, but it will become outdated after first such update as all subsequent index values will have changed due to removal of an object. So what is the correct design pattern to accurately reflect model changes in the UITableView in costant (or at least logarithmic) time?

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  • aio_write on linux with rtkaio is sometimes long

    - by Drakosha
    I'm using async io on linux with rtkaio library. In my tests everything works perfectly, but, in my real application i see that aio_write which is supposed to return very fast, is very slow. It can take more than 100 milis to write a 128KB to a O_DIRECT padded file. Both my test and the application use same I/O size, i check on the same file system (GFS). I added counting and i see that there are about 50% of async io operations that are short (shorter then 2 milis) and 50% that are long (longer than 2 milis). I also checked that the test and the application both use the same rtkaio library. I'm pretty lost, anyone any ideas where should i look? Another my related question: http://stackoverflow.com/questions/1799537/proc-sys-fs-aio-nr-is-never-higher-than-1024-aio-on-linux

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  • How to properly use CoreData validation & error framework ?

    - by Xav
    I've created a model in Xcode, and for various attributes I have minimum & maximum values defined and that are enforced by coreData at runtime. I'm using NSManagedObject validateValue:forKey:error to check for user input values. I was a bit disappointed to see that the localized error message is not specific, and I get a "The operation couldn't be completed. (Cocoa error 1620)" for too small values and a "The operation couldn't be completed. (Cocoa error 1610)" for too large values. It's written in the coreData documentation that "you can localize most aspects of a managed object model, including entity and property names and error messages". Unfortunately it's not very detailed on how you implement it for error messages. So How do you customize error message ? How do you localize them ? Is it possible to customize it in a way where it will mentioned the reference value ex: "Value should be lower than %@" or "Value should be higher than %@" ?

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  • Rails, Apache2 on Ubuntu (karmic) deployment

    - by Steve
    I just need some clarification on a couple of files. My site has an admin subdomain and SSL in addition to the normal *:80 details found in the virtual hosts. My question(s): Do I need to specify a 1) ServerName and 2) DocumentRoot in: /etc/apache2/apache2.conf? I currently enable my site from this directory: /etc/apache2/sites-available/site Here are the contents of my site file in the above directory (/etc/apache2/sites-available/site): <VirtualHost *:80> ServerName www.site.com ServerAlias www.site.com DocumentRoot /home/user/public_html/site/current/public RailsAllowModRewrite off <directory "/home/user/public_html/site/current/public"> Order allow,deny Allow from all </directory> </VirtualHost> <VirtualHost *:80> ServerName www.site.com ServerAlias admin.site.com DocumentRoot /home/user/public_html/site/current/public RailsAllowModRewrite off <directory "/home/user/public_html/site/current/public"> Order allow,deny Allow from all </directory> </VirtualHost> <VirtualHost *:443> ServerName www.site.com ServerAlias www.site.com # SSL releated SSLEngine on SSLOptions +FakeBasicAuth +ExportCertData +StrictRequire SSLCertificateFile /path/to/site.com.crt SSLCertificateChainFile /path/to/bundle.crt SSLCertificateKeyFile /path/to/site.key # Used by rails RequestHeader set X_FORWARDED_PROTO "https" </VirtualHost> Do you see anything wrong?

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  • Why does the jQuery on this page work for Internet Explorer 8, but nothing else?

    - by Ben McCormack
    I made a web page that uses jQuery: http://benmccormack.com/demo/MichaelMassPsalm/Psalm16Mode5.html When you change the selection in the combo box from Higher Key to Lower Key, all of the music images are supposed to change their source to be images that represent the lower key signature. This works great in IE8, but it won't work in Safari, Firefox, or Chrome. Why not? Here's the jQuery code that I'm using: $(document).ready(function () { $("#musicKey").change(function (event) { if ($("#musicKey").val() * 1) { $("img[src*='Low'").each(function (index) { $(this).attr("src", $(this).attr("src").replace("Low", "High")); }); } else { $("img[src*='High'").each(function (index) { $(this).attr("src", $(this).attr("src").replace("High", "Low")); }); } }); });

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  • Runtime C function details

    - by Sridhar
    Hi, Is there any way to find particular C language function's input and output parameters from a framework (apple's ARM) during the runtime or from any method with out knowing the headers. It is a framework and there are no header files for it.I decompile it with IDA Pro and it gives me the function names but not input and output parameters information. I am able to load those private functions using dlsym. Is it possible to find the parameters info in runtime (C language or Objective C) or from IDA Pro ? Regards, Raghu

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  • Operator Overloading in C

    - by Leif Andersen
    In C++, I can change the operator on a specific class by doing something like this: MyClass::operator==/*Or some other operator such as =, >, etc.*/(Const MyClass rhs) { /* Do Stuff*/; } But with there being no classes (built in by default) in C. So, how could I do operator overloading for just general functions? For example, if I remember correctly, importing stdlib.h gives you the - operator, which is just syntactic sugar for (*strcut_name).struct_element. So how can I do this in C? Thank you.

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  • C - floating point rounding

    - by hatorade
    I'm trying to understand how floating point numbers work. I think I'd like to test out what I know / need to learn by evaluating the following: I would like to find the smallest x such that x + 1 = x, where x is a floating point number. As I understand it, this would happen in the case where x is large enough so that x + 1 is closer to x than the next number higher than x representable by floating point. So intuitively it seems it would be the case where I don't have enough digits in the significand. Would this number x then be the number where the significand is all 1's. But then I can't seem to figure out what the exponent would have to be. Obviously it would have to be big (relative to 10^0, anyway).

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  • How does a VxWorks scheduler get executed?

    - by Ashwin
    Hello All, Would like to know how the scheduler gets called so that it can switch tasks. As in even if its preemptive scheduling or round robin scheduling - the scheduler should come in to picture to do any kind of task switching. Supposing a low priority task has an infinite loop - when does the scheduler intervene and switch to a higher priority task? Query is: 1. Who calls the scheduler? [in VxWorks] 2. If it gets called at regular intervals - how is that mechanism implemented? Thanks in advance. --Ashwin

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  • Function-Local Static Const variable Initialization semantics.

    - by Hassan Syed
    The questions are in bold, for those that cannot be bothered reading a question in depth. This is a followup to this question. It is to do with the initialization semantics of static variables in functions. Static variables should be initialized once, and their internal state might be altered later - as I (currently) do in the linked question. However, the code in question does not require the feature to change the state of the variable later. Let me clarrify my position, since I don't require the string object's internal state to change. The code is for a trait class for meta programming, and as such would would benifit from a const char * const ptr -- thus Ideally a local cost static const variable is needed. My educated guess is that in this case the string in question will be optimally placed in memory by the link-loader, and that the code is more secure and maps to the intended semantics. This leads to the semantics of such a variable "The C++ Programming language Third Edition -- Stroustrup" does not have anything (that I could find) to say about this matter. All that is said is that the variable is initialized once when the flow of control of the thread first reaches the code. This leads me to ponder if the following code would be sensible, and if not what are the intended semantics ?. #include <iostream> const char * const GetString(const char * x_in) { static const char * const x = x_in; return x; } int main() { const char * const temp = GetString("yahoo"); std::cout << temp << std::endl; const char * const temp2 = GetString("yahoo2"); std::cout << temp2 << std::endl; } The following compiles on GCC and prints "yahoo" twice. Which is what I want -- However it might not be standards compliant (which is why I post this question). It might be more elegant to have two functions, "SetString" and "String" where the latter forwards to the first. If it is standards compliant does someone know of a templates implementation in boost (or elsewhere) ?

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  • Can't access annotation property of subclassed uibutton

    - by Tzur Gazit
    I have a mapView to which I add annotations. The pin's callout have a button (rightCalloutAccessoryView). In order to be able to display various information when the button is pushed, i've subclassed uibutton and added a class called "Annotation". @interface CustomButton : UIButton { NSIndexPath *indexPath; Annotation *mAnnotation; } @property (nonatomic, retain) NSIndexPath *indexPath; @property (nonatomic, copy) Annotation *mAnnotation; - (id) setAnnotation2:(Annotation *)annotation; @end Here is "Annotation": @interface Annotation : NSObject <MKAnnotation> { CLLocationCoordinate2D coordinate; NSString *mPhotoID; NSString *mPhotoUrl; NSString *mPhotoName; NSString *mOwner; NSString *mAddress; } @property (nonatomic, assign) CLLocationCoordinate2D coordinate; @property (nonatomic, copy) NSString *mPhotoID; @property (nonatomic, copy) NSString *mPhotoUrl; @property (nonatomic, copy) NSString *mPhotoName; @property (nonatomic, copy) NSString *mOwner; @property (nonatomic, copy) NSString *mAddress; - (id) initWithCoordinates:(CLLocationCoordinate2D)coordinate; - (id) setPhotoId:(NSString *)id url:(NSString *)url owner:(NSString *)owner address:(NSString *)address andName:(NSString *)name; @end I want to set the annotation property of the uibutton at - (MKAnnotationView *)mapView:(MKMapView *)pMapView viewForAnnotation:(id )annotation, in order to refer to it at the button push handler (-(IBAction) showDetails:(id)sender). The problem is that I can't set the annotation property of the button. I get the following message at run time: 2010-04-27 08:15:11.781 HotLocations[487:207] *** -[UIButton setMAnnotation:]: unrecognized selector sent to instance 0x5063400 2010-04-27 08:15:11.781 HotLocations[487:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[UIButton setMAnnotation:]: unrecognized selector sent to instance 0x5063400' 2010-04-27 08:15:11.781 HotLocations[487:207] Stack: ( 32080987, 2472563977, 32462907, 32032374, 31884994, 55885, 30695992, 30679095, 30662137, 30514190, 30553882, 30481385, 30479684, 30496027, 30588515, 63333386, 31865536, 31861832, 40171029, 40171226, 2846639 ) I appreciate the help. Tzur.

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  • OS memory allocation addresses

    - by user1777914
    Quick curious question, memory allocation addresses are choosed by the language compiler or is it the OS which chooses the addresses for the memory asked? This is from a doubt about virtual memory, where it could be quickly explained as "let the process think he owns all the memory", but what happens on 64 bits architectures where only 48 bits are used for memory addresses if the process wants a higher address? Lets say you do a int a = malloc(sizeof(int)); and you have no memory left from the previous system call so you need to ask the OS for more memory, is the compiler the one who determines the memory address to allocate this variable, or does it just ask the OS for memory and it allocates it on the address returned by it?

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  • Having trouble using jQuery to set meta tag values

    - by Zhami
    I'm trying to set meta tags using jQuery (please don't reply that this doesn't make sense since search engines blah-blah-blah... I am loading invoking 3rd party Javascript functions that examine these vales, such as Tweetmeme and Facebook). If I use: $('meta[name=some-name]').attr('content', 'some value'); it does work to set the value of an existing meta tag, but does not create a meta tag if such a named one does not exist. If you have insight or experience with this, please reply...

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  • Django: Overriding the save() method: how do I call the delete() method of a child class

    - by Patti
    The setup = I have this class, Transcript: class Transcript(models.Model): body = models.TextField('Body') doPagination = models.BooleanField('Paginate') numPages = models.PositiveIntegerField('Number of Pages') and this class, TranscriptPages(models.Model): class TranscriptPages(models.Model): transcript = models.ForeignKey(Transcript) order = models.PositiveIntegerField('Order') content = models.TextField('Page Content', null=True, blank=True) The Admin behavior I’m trying to create is to let a user populate Transcript.body with the entire contents of a long document and, if they set Transcript.doPagination = True and save the Transcript admin, I will automatically split the body into n Transcript pages. In the admin, TranscriptPages is a StackedInline of the Transcript Admin. To do this I’m overridding Transcript’s save method: def save(self): if self.doPagination: #do stuff super(Transcript, self).save() else: super(Transcript, self).save() The problem = When Transcript.doPagination is True, I want to manually delete all of the TranscriptPages that reference this Transcript so I can then create them again from scratch. So, I thought this would work: #do stuff TranscriptPages.objects.filter(transcript__id=self.id).delete() super(Transcript, self).save() but when I try I get this error: Exception Type: ValidationError Exception Value: [u'Select a valid choice. That choice is not one of the available choices.'] ... and this is the last thing in the stack trace before the exception is raised: .../django/forms/models.py in save_existing_objects pk_value = form.fields[pk_name].clean(raw_pk_value) Other attempts to fix: t = self.transcriptpages_set.all().delete() (where self = Transcript from the save() method) looping over t (above) and deleting each item individually making a post_save signal on TranscriptPages that calls the delete method Any ideas? How does the Admin do it? UPDATE: Every once in a while as I'm playing around with the code I can get a different error (below), but then it just goes away and I can't replicate it again... until the next random time. Exception Type: MultiValueDictKeyError Exception Value: "Key 'transcriptpages_set-0-id' not found in " Exception Location: .../django/utils/datastructures.py in getitem, line 203 and the last lines from the trace: .../django/forms/models.py in _construct_form form = super(BaseInlineFormSet, self)._construct_form(i, **kwargs) .../django/utils/datastructures.py in getitem pk = self.data[pk_key]

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  • Android: how to convert a Drawable to Bitmap

    - by Rob
    How can I convert a Drawable to a Bitmap? I would like to set a certain drawable as the device's wallpaper, but all wallpaper functions accept Bitmaps only (I cannot use WallpaperManager - I'm pre 2.1). Also, my drawables are downloaded from the web and do not reside in R.drawable. Thanks, Rob

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  • SQL Alchemy MVC and cross controller joins

    - by Khorkrak
    When using SQL Alchemy for abstracting your data access layer and using controllers as the way to access objects from that abstraction layer, how should joins be handled? So for example, say you have an Orders controller class that manages Order objects such that it provides getOrder, saveOrder, etc methods and likewise a similar controller for User objects. First of all do you even need these controllers? Should you instead just treat SQL Alchemy as "the" thing for handling data access. Why bother with object oriented controller stuff there when you instead have a clean declarative way to obtain and persist objects without having to write SQL directly either. Well one reason could be that perhaps you may want to replace SQL Alchemy with direct SQL or Storm or whatever else. So having controller classes there to act as an intermediate layer helps limit what would need to change then. Anyway - back to the main question - so assuming you have these two controllers, now lets say you want the list of orders for a certain set of users meeting some criteria. How do you go about doing this? Generally you don't want the controllers crossing domains - the Orders controllers knows only about Orders and the User controller just about Users - they don't mess with each other. You also don't want to go fetch all the Users that match and then feed a big list of user ids to the Orders controller to go find the matching Orders. What's needed is a join. Here's where I'm stuck - that seems to mean either the controllers must cross domains or perhaps they should be done away with altogether and you simply do the join via SQL Alchemy directly and get the resulting User and / or Order objects as needed. Thoughts?

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  • Invoke Python modules from Java

    - by user36813
    I have a Python interface of a graph library written in C - igraph (the name of library). My need is to invoke the python modules pertaining to this graph library from Java code. It goes like this, the core of library is in c. This core has been imported into Python and interfaces to the functions embedded in core are available in Python. My project's rest of the code is in Java and hence I would like to call the graph functions by Java as well. Jython - which lets you invoke python modules with in Java was an option.I went on trying Jython to discover that it will not work in my case as the core code is in C and Jython wont support anything that is imported as a c dll in python code.I also thought of opting for the approach of calling graph routines directly in c. That is without passing through Python code. I am assuming there must be something which lets you call c code from Java, how ever I am not good in C hence I did not go for it. My last resort seems to execute Python interpreter from command line using Java. But that is a dirty and shameless. Also to deal with the results produced by Python code I will have to write the results in a file and read it back in java. Again dirty way. Is there something that any one can suggest me? Thanks to every one giving time. Thanks Igal for answering. I had a look at it. At first glance it appears as if it is simply calling the python script. Jep jep = new Jep(false, SCRIPT_PATH, cl); jep.set("query", query); jep.runScript(SCRIPT_PATH + file); jep.close(); Isnt it very similar to what we would do if called the python interpreter from command line through a Java code. Runtime runtime = Runtime.getRuntime(); Process proc = runtime.exec("python test.py"); Concern is how do I use the results generated by Python script. The naive way is to write them to file and read it back in Java. I am searching for a smarter approach.Thanks for suggestion anyway.

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  • Format fixed-format text file lines

    - by EugeneP
    there's a text file first second third 1 2 3 yes no ok hmmmmmmm yep_a_long_word_it_is ahahahahahahha what java functions /libs to use to align words so that they are looked like this (fixed width based on the longest column's length), let's say center align: first second third 1 2 3 yes no ok hmmmmmmm yep_a_long_word_it_is ahahahahahahha

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  • Rails paginate array items one-by-one instead of page-by-page

    - by hnovick
    Hi Guys, I have a group of assets, let's call them "practitioners". I'm displaying these practitioners in the header of a calendar interface. There are 7 columns to the calendar. 7 columns = 7 practitioners per view/page. Right now: if the first page shows you practitioners 1-7, when you go the next page you will see practitioners 8-15, next page 16-23, etc. etc. i am wondering how to page the practitioners so that if the first page shows you practitioners 1-7, the next page will show you practitioners 2-8, then 3-9, etc. etc. i would greatly appreciate any help you can offer. here is the rails code i am working with. best regards, harris novick # get the default sort order sort_order = RESOURCE_SORT_ORDER # if we've been given asset ids, start our list with them unless params[:asset_ids].blank? params[:asset_ids] = params[:asset_ids].values unless params[:asset_ids].is_a?(Array) sort_order = "#{params[:asset_ids].collect{|id| "service_provider_resources.id = #{id} DESC"}.join(",")}, #{sort_order}" end @asset_set = @provider.active_resources(:include => {:active_services => :latest_approved_version}).paginate( :per_page => RESOURCES_IN_DAY_VIEW, :page => params[:page], :order => sort_order )

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