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  • streaming xml pretty printer in C/C++ using expat or libxml2?

    - by Mark Zeren
    I have a library that outputs xml without whitespace all on one line. In some cases I'd like to pretty print that output. I'm looking for a BSD-ish licensed C/C++ library or sample code that will take a raw xml byte stream and pretty print it. Here's some pseudo code showing one way that I might use this functionality: void my_write(const char* buf, int len); PrettyPrinter pp(bind(&my_write)); while (...) { // ... get some more xml ... const char* buf = xmlSource.get_buf(); int len = xmlSource.get_buf_len(); int written = pp.write(buf, len); // calls my_write with pretty printed xml // ... error handling, maybe call write again, etc. ... } I'd like to avoid instantiating a DOM representation. I already have dependencies on the expat and libxml2 shared libraries, and I'd rather not add any more shared library dependencies.

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  • JQuery: Live <a> tag partially working second time around.

    - by BPotocki
    I have the following jquery code: $("a[id*='Add_']").live('click', function() { //Get parentID to add to. var parentID = $(this).attr('id').substring(4); //Get div. var div = $("#CreateList"); //Ajax call to refresh "CreateList" div with new XML. div.load("/AddUnit?ParentID=" + parentID); }); Basically, contained within the div is a nested unordered list with several "Add_#" links. Clicking the links uses an ajax call to recreate the list with a new node. It clears all the add links, but they are added again by the ajax call. This is why I used the .live method so newly added "Add_#" links still have the binding. This works in most cases. If I click "Add_1", the div refreshes with the new info. If I then click "Add_2", it works again as expected. The problem I'm having happens when I click "Add_1", then the page refreshes (and creates a new "Add_1" link), then I click the re-rendered "Add_1" again. It's the same link, but it was refreshed during the ajax call. When I do that, the javascript function still gets called, but the .load method doesn't work. Any ideas why this might be happening? Thanks.

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  • Indirect property notification

    - by Carlo
    Hello, this question might look a little trivial, but it might not be. I'm just wondering which of the following two cases is better for indirect property notification, or perhaps there is an even better way. The scenario: I have two properties, the first one is an object called HoldingObject, the second one is a boolean called IsHoldingObject, which is false if HoldingObject == null, otherwise it's true. I'm just wondering what is the best notification mechanism for IsHoldingObject: Case (A) - Notify IsHoldingObject changed from the HoldingObject proeperty: public class NotifyingClass1 : INotifyPropertyChanged { private object _holdingObject; public object HoldingObject { get { return _holdingObject; } set { if (_holdingObject != value) { _holdingObject = value; NotifyPropertyChanged("HoldingObject"); // Notify from the property that is being checked NotifyPropertyChanged("IsHoldingObject"); } } } public bool IsHoldingObject { get { return this.HoldingObject == null; } } #region INotifyPropertyChanged Members public event PropertyChangedEventHandler PropertyChanged; private void NotifyPropertyChanged(string propertyName) { if (this.PropertyChanged != null) this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); } #endregion } Case (B) - Notify IsHoldingObject changed from the IsHoldingObject directly, by setting it to false or true from HoldingObject property: public class NotifyingClass2 : INotifyPropertyChanged { private object _holdingObject; public object HoldingObject { get { return _holdingObject; } set { if (_holdingObject != value) { _holdingObject = value; NotifyPropertyChanged("HoldingObject"); // 1) Set the property here this.IsHoldingObject = _holdingObject != null; } } } private bool _isHoldingObject; public bool IsHoldingObject { get { return _isHoldingObject; } set { if (_isHoldingObject != value) { _isHoldingObject = value; // 2) Notify directly from the property NotifyPropertyChanged("IsHoldingObject"); } } } #region INotifyPropertyChanged Members public event PropertyChangedEventHandler PropertyChanged; private void NotifyPropertyChanged(string propertyName) { if (this.PropertyChanged != null) this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); } #endregion } I personally lean to the first one because it requires less code, but I'm not sure how recommendable it is to do that. Let me know if there is another (better) way. Thanks!

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  • Does Function pointer make the program slow?

    - by drigoSkalWalker
    Hi guys. I read about function pointers in C And everyone said that will make my program run slow. Is it true? I made a program to check it. And I got the same results on both cases. (mesure the time.) So, is it bad to use fuction pointer? Thanks in advance. To response for some guys. I said 'run slow' for the time that I have compared on a loop. like this. int end = 1000; int i = 0; while (i < end) { fp = func; fp (); } When you execute this, i got the same time if I execute this. while (i < end) { func (); } So I think that function pointer have no difference of time and it don't make a program run slow as many people said.

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  • Efficient (basic) regular expression implementation for streaming data

    - by Brendan Dolan-Gavitt
    I'm looking for an implementation of regular expression matching that operates on a stream of data -- i.e., it has an API that allows a user to pass in one character at a time and report when a match is found on the stream of characters seen so far. Only very basic (classic) regular expressions are needed, so a DFA/NFA based implementation seems like it would be well-suited to the problem. Based on the fact that it's possible to do regular expression matching using a DFA/NFA in a single linear sweep, it seems like a streaming implementation should be possible. Requirements: The library should try to wait until the full string has been read before performing the match. The data I have really is streaming; there is no way to know how much data will arrive, it's not possible to seek forward or backward. Implementing specific stream matching for a couple special cases is not an option, as I don't know in advance what patterns a user might want to look for. For the curious, my use case is the following: I have a system which intercepts memory writes inside a full system emulator, and I would like to have a way to identify memory writes that match a regular expression (e.g., one could use this to find the point in the system where a URL is written to memory). I have found (links de-linkified because I don't have enough reputation): stackoverflow.com/questions/1962220/apply-a-regex-on-stream stackoverflow.com/questions/716927/applying-a-regular-expression-to-a-java-i-o-stream www.codeguru.com/csharp/csharp/cs_data/searching/article.php/c14689/Building-a-Regular-Expression-Stream-Search-with-the-NET-Framework.htm But all of these attempt to convert the stream to a string first and then use a stock regular expression library. Another thought I had was to modify the RE2 library, but according to the author it is architected around the assumption that the entire string is in memory at the same time. If nothing's available, then I can start down the unhappy path of reinventing this wheel to fit my own needs, but I'd really rather not if I can avoid it. Any help would be greatly appreciated!

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  • Matching on search attributes selected by customer on front end

    - by CodeNinja1974
    I have a method in a class that allows me to return results based on a certain set of Customer specified criteria. The method matches what the Customer specifies on the front end with each item in a collection that comes from the database. In cases where the customer does not specify any of the attributes, the ID of the attibute is passed into the method being equal to 0 (The database has an identity on all tables that is seeded at 1 and is incremental). In this case that attribute should be ignored, for example if the Customer does not specify the Location then customerSearchCriteria.LocationID = 0 coming into the method. The matching would then match on the other attributes and return all Locations matching the other attibutes, example below: public IEnumerable<Pet> FindPetsMatchingCustomerCriteria(CustomerPetSearchCriteria customerSearchCriteria) { if(customerSearchCriteria.LocationID == 0) { return repository.GetAllPetsLinkedCriteria() .Where(x => x.TypeID == customerSearchCriteria.TypeID && x.FeedingMethodID == customerSearchCriteria.FeedingMethodID && x.FlyAblityID == customerSearchCriteria.FlyAblityID ) .Select(y => y.Pet); } } The code for when all criteria is specified is shown below: private PetsRepository repository = new PetsRepository(); public IEnumerable<Pet> FindPetsMatchingCustomerCriteria(CustomerPetSearchCriteria customerSearchCriteria) { return repository.GetAllPetsLinkedCriteria() .Where(x => x.TypeID == customerSearchCriteria.TypeID && x.FeedingMethodID == customerSearchCriteria.FeedingMethodID && x.FlyAblityID == customerSearchCriteria.FlyAblityID && x.LocationID == customerSearchCriteria.LocationID ) .Select(y => y.Pet); } I want to avoid having a whole set of if and else statements to cater for each time the Customer does not explicitly select an attribute of the results they are looking for. What is the most succint and efficient way in which I could achieve this?

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  • facebook Hacker cup: studious Student problem.

    - by smartmuki
    During the qualification round, the following question was asked: You've been given a list of words to study and memorize. Being a diligent student of language and the arts, you've decided to not study them at all and instead make up pointless games based on them. One game you've come up with is to see how you can concatenate the words to generate the lexicographically lowest possible string. Input As input for playing this game you will receive a text file containing an integer N, the number of word sets you need to play your game against. This will be followed by N word sets, each starting with an integer M, the number of words in the set, followed by M words. All tokens in the input will be separated by some whitespace and, aside from N and M, will consist entirely of lowercase letters. Output Your submission should contain the lexicographically shortest strings for each corresponding word set, one per line and in order. Constraints 1 <= N <= 100 1 <= M <= 9 1 <= all word lengths <= 10 Example input 5 6 facebook hacker cup for studious students 5 k duz q rc lvraw 5 mybea zdr yubx xe dyroiy 5 jibw ji jp bw jibw 5 uiuy hopji li j dcyi Example output cupfacebookforhackerstudentsstudious duzklvrawqrc dyroiymybeaxeyubxzdr bwjibwjibwjijp dcyihopjijliuiuy The program I wrote goes as: chomp($numberElements=<STDIN>); for(my $i=0; $i < $numberElements; $i++) { my $string; chomp ($string = <STDIN>); my @array=split(/\s+/,$string); my $number=shift @array; @sorted=sort @array; $sortedStr=join("",@sorted); push(@data,$sortedStr); } foreach (@data) { print "$_\n"; } The program gives the correct output for the given test cases but still facebook shows it to be incorrect. Is there something wrong with the program??

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  • Extracting DCT coefficients from encoded images and video

    - by misha
    Is there a way to easily extract the DCT coefficients (and quantization parameters) from encoded images and video? Any decoder software must be using them to decode block-DCT encoded images and video. So I'm pretty sure the decoder knows what they are. Is there a way to expose them to whomever is using the decoder? I'm implementing some video quality assessment algorithms that work directly in the DCT domain. Currently, the majority of my code uses OpenCV, so it would be great if anyone knows of a solution using that framework. I don't mind using other libraries (perhaps libjpeg, but that seems to be for still images only), but my primary concern is to do as little format-specific work as possible (I don't want to reinvent the wheel and write my own decoders). I want to be able to open any video/image (H.264, MPEG, JPEG, etc) that OpenCV can open, and if it's block DCT-encoded, to get the DCT coefficients. In the worst case, I know that I can write up my own block DCT code, run the decompressed frames/images through it and then I'd be back in the DCT domain. That's hardly an elegant solution, and I hope I can do better. Presently, I use the fairly common OpenCV boilerplate to open images: IplImage *image = cvLoadImage(filename); // Run quality assessment metric The code I'm using for video is equally trivial: CvCapture *capture = cvCaptureFromAVI(filename); while (cvGrabFrame(capture)) { IplImage *frame = cvRetrieveFrame(capture); // Run quality assessment metric on frame } cvReleaseCapture(&capture); In both cases, I get a 3-channel IplImage in BGR format. Is there any way I can get the DCT coefficients as well?

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  • Can you dynamically combine multiple conditional functions into one in Python?

    - by erich
    I'm curious if it's possible to take several conditional functions and create one function that checks them all (e.g. the way a generator takes a procedure for iterating through a series and creates an iterator). The basic usage case would be when you have a large number of conditional parameters (e.g. "max_a", "min_a", "max_b", "min_b", etc.), many of which could be blank. They would all be passed to this "function creating" function, which would then return one function that checked them all. Below is an example of a naive way of doing what I'm asking: def combining_function(max_a, min_a, max_b, min_b, ...): f_array = [] if max_a is not None: f_array.append( lambda x: x.a < max_a ) if min_a is not None: f_array.append( lambda x: x.a > min_a ) ... return lambda x: all( [ f(x) for f in f_array ] ) What I'm wondering is what is the most efficient to achieve what's being done above? It seems like executing a function call for every function in f_array would create a decent amount of overhead, but perhaps I'm engaging in premature/unnecessary optimization. Regardless, I'd be interested to see if anyone else has come across usage cases like this and how they proceeded. Also, if this isn't possible in Python, is it possible in other (perhaps more functional) languages?

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  • Why the compiler is not compiling a line in C++ Builder?

    - by MLB
    Hi boys: I was programming an application in C++ Builder 6, and I had encountered this rare problem: void RotateDice() { Graphics::TBitmap *MYbitmap = new Graphics::TBitmap(); Randomize(); int rn = random(6) + 1; switch (rn) { case 1: { //... break; } //... Some cases... } ShowDice(); //it's a function to show the dice delete MYbitmap; //the compiler don't get it!!!! } In the line "ShowDice()", the compiler jumps to the final of the RotateDice() method, it doesn't "see" the line "delete MYbitmap". When I compile the program, every compiled line shows a little blue point in its left side, but that line don't show the blue point... it's like the compiler don't "see" the line of code. What's happening with that???? Note: Some days ago, I was writing a program in Delphi and I was advice of that problematic issue. Some like that happened to me in Delphi 7... So, waht the problem with that? I am so sorry about my English. I am from Cuba.

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  • Link failure with either abnormal memory consumption or LNK1106 in Visual Studio 2005.

    - by Corvin
    Hello, I am trying to build a solution for windows XP in Visual Studio 2005. This solution contains 81 projects (static libs, exe's, dlls) and is being successfully used by our partners. I copied the solution bundle from their repository and tried setting it up on 3 similar machines of people in our group. I was successful on two machines and the solution failed to build on my machine. The build on my machine encountered two problems: During a simple build creation of the biggest static library (about 522Mb in debug mode) would fail with the message "13libd\ui1d.lib : fatal error LNK1106: invalid file or disk full: cannot seek to 0x20101879" Full solution rebuild creates this library, however when it comes to linking the library to main .exe file, devenv.exe spawns link.exe which consumes about 80Mb of physical memory and 250MB of virtual and spawns another link.exe, which does the same. This goes on until the system runs out of memory. On PCs of my colleagues where successful build could be performed, there is only one link.exe process which uses all the memory required for linking (about 500Mb physical). There is a plenty of hard drive space on my machine and the file system is NTFS. All three of our systems are similar - Core2Quad processors, 4Gb of RAM, Windows XP SP3. We are using Visual studio installed from the same source. I tried using a different RAM and CPU, using dedicated graphics adapter to eliminate possibility of video memory sharing influencing the build, putting solution files to different location, using different versions of VS 2005 (Professional, Standard and Team Suite), changing the amount of available virtual memory, running memtest86 and building the project from scratch (i.e. a clean bundle). I have read what MSDN says about LNK1106, none of the cases apply to me except for maybe "out of heap space", however I am not sure how I should fight this. The only idea that I have left is reinstalling the OS, however I am not sure that it would help and I am not sure that my situation wouldn't repeat itself on a different machine. Would anyone have any sort of advice for me? Thanks

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  • Is there a design pattern to cut down on code duplication when subclassing Activities in Android?

    - by Daniel Lew
    I've got a common task that I do with some Activities - downloading data then displaying it. I've got the downloading part down pat; it is, of course, a little tricky due to the possibility of the user changing the orientation or cancelling the Activity before the download is complete, but the code is there. There is enough code handling these cases such that I don't want to have to copy/paste it to each Activity I have, so I thought to create an abstract subclass Activity itself such that it handles a single background download which then launches a method which fills the page with data. This all works. The issue is that, due to single inheritance, I am forced to recreate the exact same class for any other type of Activity - for example, I use Activity, ListActivity and MapActivity. To use the same technique for all three requires three duplicate classes, except each extends a different Activity. Is there a design pattern that can cut down on the code duplication? As it stands, I have saved much duplication already, but it pains me to see the exact same code in three classes just so that they each subclass a different type of Activity.

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  • Efficient Multiplication of Varying-Length #s [Conceptual]

    - by Milan Patel
    Write the pseudocode of an algorithm that takes in two arbitrary length numbers (provided as strings), and computes the product of these numbers. Use an efficient procedure for multiplication of large numbers of arbitrary length. Analyze the efficiency of your algorithm. I decided to take the (semi) easy way out and use the Russian Peasant Algorithm. It works like this: a * b = a/2 * 2b if a is even a * b = (a-1)/2 * 2b + a if a is odd My pseudocode is: rpa(x, y){ if x is 1 return y if x is even return rpa(x/2, 2y) if x is odd return rpa((x-1)/2, 2y) + y } I have 3 questions: Is this efficient for arbitrary length numbers? I implemented it in C and tried varying length numbers. The run-time in was near-instant in all cases so it's hard to tell empirically... Can I apply the Master's Theorem to understand the complexity...? a = # subproblems in recursion = 1 (max 1 recursive call across all states) n / b = size of each subproblem = n / 1 - b = 1 (problem doesn't change size...?) f(n^d) = work done outside recursive calls = 1 - d = 0 (the addition when a is odd) a = 1, b^d = 1, a = b^d - complexity is in n^d*log(n) = log(n) this makes sense logically since we are halving the problem at each step, right? What might my professor mean by providing arbitrary length numbers "as strings". Why do that? Many thanks in advance

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  • How to deal with a Java serialized object whose package changed?

    - by Alex
    I have a Java class that is stored in an HttpSession object that's serialized and transfered between servers in a cluster environment. For the purpose of this explanation, lets call this class "Person". While in the process of improving the code, this class was moved from "com.acme.Person" to "com.acme.entity.Person". Internally, the class remains exactly the same (same fields, same methods, same everything). The problem is that we have two sets of servers running the old code and the new code at the same time. The servers with the old code have serialized HttpSession object and when the new code unserializes it, it throws a ClassNotFoundException because it can't find the old reference to com.acme.Person. At this point, it's easy to deal with this because we can just recreate the object using the new package. The problem then becomes that the HttpSession in the new servers, will serialize the object with the new reference to com.acme.entity.Person, and when this is unserialized in the servers running the old code, another exception will be thrown. At this point, we can't deal with this exception anymore. What's the best strategy to follow for this kind of cases? Is there a way to tell the new servers to serialize the object with the reference to the old package and unserialize references to the old package to the new one? How would we transition to using the new package and forgetting about the old one once all servers run the new code?

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  • How to define default values optional fields in play framework forms?

    - by natalinobusa
    I am implementing a web api using the scala 2.0.2 play framework. I would like to extract and validate a number of get parameters. And for this I am using a play "form" which allows me to define optional fields. Problem: For those optional fields, I need to define a default value if the parameter is not passed. The code is intended to parse correctly these three use cases: /test?top=abc (error, abc is not an integer) /test?top=123 (valid, top is 123) /test (valid, top is 42 (default value)) I have come up with the following code: def test = Action { implicit request => case class CData(top:Int) val p = Form( mapping( "top" -> optional(number) )((top) => CData($top.getOrElse(42))) ((cdata:CData) => Some(Some(cdata.top))) ).bindFromRequest() Ok("all done.") } The code works, but it's definitely not elegant. There is a lot of boiler plate going on just to set up a default value for a missing request parameter. Can anyone suggest a cleaner and more coincise solution?

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  • Best "Loading" feedback for ASP.Net?

    - by IP
    So, we have an ASP.Net application - fairly standard - and in there are lots of updatepanels, and postbacks. On some pages we have <ajax:UpdatePanelAnimationExtender ID="ae" runat="server" TargetControlID="updatePanel" BehaviorID="UpdateAnimation"> <Animations> <OnUpdating> <FadeOut Duration="0.1" minimumOpacity=".3" /> </OnUpdating> <OnUpdated> <FadeIn minimumOpacity=".5" Duration="0" /> </OnUpdated> </Animations> </ajax:UpdatePanelAnimationExtender> Which basically whites out the page when a postback is going on (but this clashes with modal dialog grey backgrounds). In some cases we have a progressupdate control which just has a spinny icon in the middle of the page. But none of them seem particularly nice and all a bit clunky. They also require a lot of code in various places around the app. What methods do other people use and find effective?

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  • When is a bool not a bool (compiler warning C4800)

    - by omatai
    Consider this being compiled in MS Visual Studio 2005 (and probably others): CPoint point1( 1, 2 ); CPoint point2( 3, 4 ); const bool point1And2Identical( point1 == point2 ); // C4800 warning const bool point1And2TheSame( ( point1 == point2 ) == TRUE ); // no warning What the...? Is the MSVC compiler brain-dead? As far as I can tell, TRUE is #defined as 1, without any type information. So by what magic is there any difference between these two lines? Surely the type of the expression inside the brackets is the same in both cases? [This part of the question now satisfactorily answered in the comments just below] Personally, I think that avoiding the warning by using the == TRUE option is ugly (though less ugly than the != 0 alternative, despite being more strictly correct), and it is better to use #pragma warning( disable:4800 ) to imply "my code is good, the compiler is an ass". Agree? Note - I have seen all manner of discussion on C4800 talking about assigning ints to bools, or casting a burger combo with large fries (hold the onions) to a bool, and wondering why there are strange results. I can't find a clear answer on what seems like a much simpler question... that might just shine line on C4800 in general.

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  • BufferedImage & ColorModel in Java

    - by spol
    I am using a image processing library in java to manipulate images.The first step I do is I read an image and create a java.awt.Image.BufferedImage object. I do it in this way, BufferedImage sourceImage = ImageIO.read( new File( filePath ) ); The above code creates a BufferedImage ojbect with a DirectColorModel: rmask=ff0000 gmask=ff00 bmask=ff amask=0. This is what happens when I run the above code on my macbook. But when I run this same code on a linux machine (hosted server), this creates a BufferedImage object with ColorModel: #pixelBits = 24 numComponents = 3 color space = java.awt.color.ICC_ColorSpace@c39a20 transparency = 1 has alpha = false isAlphaPre = false. And I use the same jpg image in both the cases. I don't know why the color model on the same image is different when run on mac and linux. The colormodel for mac has 4 components and the colormodel for linux has 3 components.There is a problem arising because of this, the image processing library that I use always assumes that there are always 4 components in the colormodel of the image passed, and it throws array out of bounds exception when run on linux box. But on macbook, it runs fine. I am not sure if I am doing something wrong or there is a problem with the library. Please let me know your thoughts. Also ask me any questions if I am not making sense!

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  • When is it safe to use a broken hash function?

    - by The Rook
    It is trivial to use a secure hash function like SHA256 and continuing to use md5 is reckless behavior. However, there are some complexities to hash function vulnerabilities that I would like to better understand. Collisions have been generated for md4 and md5. According to NIST md5() is not a secure hash function. It only takes 2^39th operations to generate a collision and should never be used for passwords. However SHA1 is vulnerable to a similar collision attack in which a collision can be found in 2^69 operations, where as brute force is 2^80th. No one has generated a sha1 collision and NIST still lists sha1 as a secure message digest function. So when is it safe to use a broken hash function? Even though a function is broken it can still be "big enough". According to Schneier a hash function vulnerable to a collsion attack can still be used as an HMAC. I believe this is because the security of an HMAC is Dependant on its secret key and a collision cannot be found until this key is obtained. Once you have the key used in a HMAC its already broken, so its a moot point. What hash function vulnerabilities would undermine the security of an HMAC? Lets take this property a bit further. Does it then become safe to use a very weak message digest like md4 for passwords if a salt is perpended to the password? Keep in mind the md4 and md5 attacks are prefixing attacks, and if a salt is perpended then an attacker cannot control the prefix of the message. If the salt is truly a secret, and isn't known to the attacker, then does it matter if its a appended to the end of the password? Is it safe to assume that an attacker cannot generate a collision until the entire message has been obtained? Do you know of other cases where a broken hash function can be used in a security context without introducing a vulnerability? (Please post supporting evidence because it is awesome!)

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  • Is it acceptable to wrap PHP library functions solely to change the names?

    - by Carson Myers
    I'm going to be starting a fairly large PHP application this summer, on which I'll be the sole developer (so I don't have any coding conventions to conform to aside from my own). PHP 5.3 is a decent language IMO, despite the stupid namespace token. But one thing that has always bothered me about it is the standard library and its lack of a naming convention. So I'm curious, would it be seriously bad practice to wrap some of the most common standard library functions in my own functions/classes to make the names a little better? I suppose it could also add or modify some functionality in some cases, although at the moment I don't have any examples (I figure I will find ways to make them OO or make them work a little differently while I am working). If you saw a PHP developer do this, would you think "Man, this is one shoddy developer?" Additionally, I don't know much (or anything) about if/how PHP is optimized, and I know that usually PHP performace doesn't matter. But would doing something like this have a noticeable impact on the performance of my application?

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  • Should we point to an NSManagedObject entity with weak instead of strong pointer?

    - by Jim Thio
    I think because NSManagedObject is managed by the managedObject context the pointer should be weak. Yet it often goes back to 0 in my cases. for (CategoryNearby * CN in sorted) { //[arrayOfItems addObject:[NSString stringWithFormat:@"%@ - %d",CN.name,[CN.order intValue]]]; NearbyShortcutTVC * tvc=[[NearbyShortcutTVC alloc]init]; tvc.categoryNearby =CN; // tvc.titleString=[NSString stringWithFormat:@"%@",CN.name]; // tvc.displayed=CN.displayed; [arrayOfItemsLocal addObject:tvc]; //CN PO(tvc); PO(tvc.categoryNearby); while (false); } self.arrayOfItems = arrayOfItemsLocal; PO(self.categoriesNearbyInArrayOfItems); [self.tableViewa reloadData]; ... Yet somewhere down the line: tvc.categoryNearby becomes nil. I do not know how or when or where it become nil. How do I debug this? Or should the reference be strong instead? This is the interface of NearbyShortcutTVC by the way @interface NearbyShortcutTVC : BGBaseTableViewCell{ } @property (weak, nonatomic) CategoryNearby * categoryNearby; @end To make sure that we're talking about the same object I print all the memory addresses of the NSArray They're both the exact same object. But somehow the categoryNearby property of the object is magically set to null somewhere. self.categoriesNearbyInArrayOfItems: ( 0x883bfe0, 0x8b6d420, 0x8b6f9f0, 0x8b71de0, 0xb073f90, 0xb061a10, 0xb06a880, 0x8b74940, 0x8b77110, 0x8b794e0, 0x8b7bf40, 0x8b7cef0, 0x8b7f4b0, 0x8b81a30, 0x88622d0, 0x8864e60, 0xb05c9a0 ) self.categoriesNearbyInArrayOfItems: ( 0x883bfe0, 0x8b6d420, 0x8b6f9f0, 0x8b71de0, 0xb073f90, 0xb061a10, 0xb06a880, 0x8b74940, 0x8b77110, 0x8b794e0, 0x8b7bf40, 0x8b7cef0, 0x8b7f4b0, 0x8b81a30, 0x88622d0, 0x8864e60, 0xb05c9a0 )

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  • How to differentiate between exceptions i can show the user, and ones i can't?

    - by Ian Boyd
    i have some business logic that traps some logically invalid situations, e.g. trying to reverse a transaction that was already reversed. In this case the correct action is to inform the user: Transaction already reversed or Cannot reverse a reversing transaction or You do not have permission to reverse transactions or This transaction is on a session that has already been closed or This transaction is too old to be reversed The question is, how do i communicate these exceptional cases back to the calling code, so they can show the user? Do i create a separate exception for each case: catch (ETransactionAlreadyReversedException) MessageBox.Show('Transaction already reversed') catch (EReversingAReversingTransactionException) MessageBox.Show('Cannot reverse a reversing transaction') catch (ENoPermissionToReverseTranasctionException) MessageBox.Show('You do not have permission to reverse transactions') catch (ECannotReverseTransactionOnAlredyClosedSessionException) MessageBox.Show('This transaction is on a session that has already been closed') catch (ECannotReverseTooOldTransactionException) MessageBox.Show('This transaction is too old to be reversed') Downside for this is that when there's a new logical case to show the user: Tranasctions created by NSL cannot be reversed i don't simply show the user a message, and instead it leaks out as an unhandled excpetion, when really it should be handled with another MessageBox. The alternative is to create a single exception class: `EReverseTransactionException` With the understanding that any exception of this type is a logical check, that should be handled with a message box: catch (EReverseTransactionException) But it's still understood that any other exceptions, ones that involve, for example, an memory ECC parity error, continue unhandled. In other words, i don't convert all errors that can be thrown by the ReverseTransaction() method into EReverseTransactionException, only ones that are logically invalid cause of the user.

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  • Extended slice that goes to beginning of sequence with negative stride

    - by recursive
    Bear with me while I explain my question. Skip down to the bold heading if you already understand extended slice list indexing. In python, you can index lists using slice notation. Here's an example: >>> A = list(range(10)) >>> A[0:5] [0, 1, 2, 3, 4] You can also include a stride, which acts like a "step": >>> A[0:5:2] [0, 2, 4] The stride is also allowed to be negative, meaning the elements are retrieved in reverse order: >>> A[5:0:-1] [5, 4, 3, 2, 1] But wait! I wanted to see [4, 3, 2, 1, 0]. Oh, I see, I need to decrement the start and end indices: >>> A[4:-1:-1] [] What happened? It's interpreting -1 as being at the end of the array, not the beginning. I know you can achieve this as follows: >>> A[4::-1] [4, 3, 2, 1, 0] But you can't use this in all cases. For example, in a method that's been passed indices. My question is: Is there any good pythonic way of using extended slices with negative strides and explicit start and end indices that include the first element of a sequence? This is what I've come up with so far, but it seems unsatisfying. >>> A[0:5][::-1] [4, 3, 2, 1, 0]

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  • best web database solution for scala for a high traffic site?

    - by egervari
    I am in charge of a rebuilding a website that gets about 250,000 visitors a day. We'd like to use Scala, but it does not work very well with Spring (in some minor cases) and Hibernate (there is a major and very annoying mismatch here if you want to use scala collections, which we do). The application itself is going to have about 40-50 tables. Other than Hibernate, is there an ORM that works awesome with Scala and is as performant and reliable as Hibernate? Does it also have the same capabilities, or are we going to run into leaky-abstractions if we don't use Hibernate? It would be a big risk for us to go with a framework that is newer and doesn't seem to have a lot of industry backing... and at the same time, Hibernate is a real pain to program against when using Scala. 1) The Java Collection <- Scala Collection is absolutely painful. There is a lot more boilerplate and crap to write. 2) The IDE doesn't import JavaConversions and java interfaces automatically... so we this needs to be done manually. Optimizing Imports in IDEA is going to destroy all the manual work. 3) There is also a performance cost to converting back and forth all the time in your domain objects and your dao classes. 4) Not to mention there needs to be a lot of casting, which produces code ugly as sin. I actually would love to write my own orm that is 100% tailored to scala, but obviously this is really outside of the scope of our project for now. So what is the best approach?

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  • T4MVC Optional Parameter Inferred From Current Context

    - by Itakou
    I have read the other post about this at T4MVC OptionalParameter values implied from current context and I am using the latest T4MVC (2.11.1) which is suppose to have the fix in. I even checked checked to make sure that it's there -- and it is. I am still getting the optional parameters filled in based on the current context. For example: Let's say I have a list that is by default ordered by a person's last name. I have the option to order by first name instead with the URL http://localhost/list/stuff?orderby=firstname When I am in that page, I want to go back to order by first name with the code: @Html.ActionLink("order by last name", MVC.List.Stuff(null)) the link I wanted was simply http://localhost/list/stuff without any parameters to keep the URL simple and short - invoking default behaviors within the action. But instead the orderby is kept and the url is still http://localhost/list/stuff?orderby=firstname Any help would be great. I know that in the most general cases, this does remove the query parameter - maybe I do have a specific case where it was not removed. I find that it only happens when I have the URL inside a page that I included with RenderPartial. My actual code is <li>@Html.ActionLink("Recently Updated", MVC.Network.Ticket.List(Model.UI.AccountId, "LastModifiedDate", null, null, null, null, null))</li> <li>@Html.ActionLink("Recently Created", MVC.Network.Ticket.List(Model.UI.AccountId, "CreatedDate", null, null, null, null, null))</li> <li>@Html.ActionLink("Most Severe", MVC.Network.Ticket.List(Model.UI.AccountId, "MostSevere", null, null, null, null, null))</li> <li>@Html.ActionLink("Previously Closed", MVC.Network.Ticket.List(Model.UI.AccountId, "LastModifiedDate", null, "Closed", null, null, null))</li> the problem happens when someone clicks Previously Closed and and go to ?status=closed. When they click Recently Updated, which I want to the ?status so that it shows the active ones, the ?status=closed stays. Any insight would be greatly appreciated.

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