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• Best practice how to store HTML in a database column

  - by tbrandao

  I have an application that modifies a table dynamically, think spreadsheet), then upon saving the form (which the table is part of) ,I store that changed table (with user modifications) in a database column named html_Spreadhseet,along with the rest of the form data. right now I'm just storing the html in a plain text format with basic escaping of characters... I'm aware that this could be stored as a separate file, the source table (html_workseeet) already is. But from a data handling perspective its easier to save the changed html table to and from a column so as to avoid having to come up with a file management strategy (which folder will this live in, now must include folder in backups, security issues now need to apply to files, how to sync db security with file system etc.), so to minimize these issues I'm only storing the ... part in the database column. My question is should I gzip the HTML , maybe use JSON, or some other format to easily store and retrieve the HTML from the database column, what is the best practice to store HTML content in a datbase? Or just store it as I currently am as an escaped text column?

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• Why does GLSL's arithmetic functions yield so different results on the iPad than on the simulator?

  - by cheeesus

  I'm currently chasing some bugs in my OpenGL ES 2.0 fragment shader code which is running on iOS devices. The code runs fine in the simulator, but on the iPad it has huge problems and some of the calculations yield vastly different results, I had for example 0.0 on the iPad and 4013.17 on the simulator, so I'm not talking about small differences which could be the result of some rounding errors. One of the things I noticed is that, on the iPad, float1 = pow(float2, 2.0); can yield results which are very different from the results of float1 = float2 * float2; Specifically, when using pow(x, 2.0) on a variable containing a larger negative number like -8, it seemed to return a value which satified the condition if (powResult <= 0.0). Also, the result of both operations (pow(x, 2.0) as well as x*x) yields different results in the simulator than on the iPad. Used floats are mediump, but I get the same stuff with highp. Is there a simple explanation for those differences? I'm narrowing the problem down, but it takes so much time, so maybe someone can help me here with a simple explanation.

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• Java "Pool" of longs or Oracle sequence with reusable values

  - by Anthony Accioly

  Several months ago I implemented a solution to choose unique values from a range between 1 and 65535 (16 bits). This range is used to generate unique Route Targets suffixes, which for this customer massive network (it's a huge ISP) are a very disputed resource, so any free index needs to become immediately available to the end user. To tackle this requirement I used a BitSet. Allocate on the RT index with set and deallocate a suffix with clear. The method nextClearBit() can find the next available index. I handle synchronization / concurrency issues manually. This works pretty well for a small range... The entire index is small (around 10k), it is blazing fast and can be easy serialized into a Blob field. The problem is, some new devices can handle RTs of 32 bits (range 1 / 4294967296). Which can't be managed with a BitSet (it would, by itself, consume around 600Mb, plus be limited to int range). Even with this massive range available, the client still wants to free available Route Targets for the end user, mainly because the lowest ones (up to 65535) - which are compatible with old routers - are being heavily disputed. Before I tell the customer that this is impossible and he will have to conform with my reusable index for lower RTs (up to 65550) and use a database sequence for the other ones (which means that when the user frees a Route Target, it will not become available again). Would anyone shed some light? Maybe some kind soul already implemented a high performance number pool for Java (6 if it matters), or I am missing a killer feature of Oracle database (11R2 if it matters)... Wishful thinking. Thank you very much in advance.

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• Java queue and multi-dimention array question? [Beginner level]

  - by javaLearner.java

  First of all, this is my code (just started learning java): Queue<String> qe = new LinkedList<String>(); qe.add("b"); qe.add("a"); qe.add("c"); qe.add("d"); qe.add("e"); My question: Is it possible to add element to the queue with two values, like: qe.add("a","1"); // where 1 is integer So, that I know element "a" have value 1. If I want to add a number let say "2" to element a, I will have like a = 3. If this cant be done, what else in java classes that can handle this? I tried to use multi-dimention array, but its kinda hard to do the queue, like pop, push etc. (Maybe I am wrong) How to call specific element in the queue? Like, call element a, to check its value. [Note] Please don't give me links that ask me to read java docs. I was reading, and I still dont get it. The reason why I ask here is because, I know I can find the answer faster and easier.

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• Why would an OS X bundle take about 30 seconds to open?

  - by Aftermathew

  Hi, We wrote a simple OS X executable in objective c. It opens and runs very quickly when called. We then put that executable into a .app bundle. When calling "open" from the command line on that bundle, or double clicking the app from the finder the "open" call can take upwards of 30 seconds to return. This is especially confusing because "open" clearly starts the executable right away (I can see it running in the process list right away, and have other indications that it's doing work), but when done from the command line, the "open" command takes a long time to return, and when done from the Finder the icon will bounce for a very long time before acting normal. I know the executable itself still opens very quickly because calling "open" on the executable inside my bundle returns very quickly, however calling it on the .app runs the code right away but takes 30 seconds or so to return. Has anyone run into this before? Do you have any suggestions for what could cause something like this? I've not been able to see anything funny in the bundle structure or the plist, but maybe I'm missing something. Thanks,

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• Where to give feedback on a new Feature is SO ?

  - by justjoe

  After using SO, for sometimes, i realize i got some problems. zen masters fighting each other on one of my question. Every side have their own arguments and Everybody seem right. Frankly, this make me confuse : How can i choose somebody's answer where personally i don't know the right answer. So, i would like to propose a feature 'i choose this because' for a user who asked. So at least he/she explain why he choose the particular answer. Maybe it's silly, but as somebody who getting helps from other's answer, i would like to know everybody get what they deserve. Usually in this kind of situation, i just upvote every good answer and check the one i think the right one. Second feature : every hot question always got plenty answer and comment. And if among person who answer it, start to debate then it will become a little bit hectic. Right now a page only have ability to sort answer based on oldest, newest votest. So, is it possible to make a new sort based on timeline what make comment and answer collide. I believe it will be more easy to read. this feature can only see by the person who create the question, or also for public.

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• Most awkward/misleading method in Java Base API ?

  - by JG

  I was recently trying to convert a string literal into a boolean, when the method "boolean Boolean.getBoolean(String name)" popped out of the auto-complete window. There was also another method ("boolean Boolean.parseBoolean(String s)") appearing right after, which lead me to search to find out what were the differences between these two, as they both seemed to do the same. It turns out that what Boolean.getBoolean(String name) really does is to check if there exists a System property (!) of the given name and if its value is true. I think this is very misleading, as I'm definitely not expecting that a method of Boolean is actually making a call to System.getProperty, and just by looking at the method signature, it sure looks (at least to me) like it should be used to parse a String as a boolean. Sure, the javadoc states it clearly, but I still think the method has a misleading name and is not in the right place. Other primitive type wrappers, such as Integer also have a similar method. Also, it doesn't seem to be a very useful method to belong in the base API, as I think it's not very common to have something like -Darg=true. Maybe it's a good question for a Java position interview: "What is the output of Boolean.getBoolean("true")?". I believe a more appropriate place for those methods would be in the System class, e.g., getPropertyAsBoolean; but again, I still think it's unnecessary to have these methods in the base API. It'd make sense to have these in something like the Properties class, where it's very common to do this kind of type conversions. What do you think of all this ? Also, if there's another "awkward" method that you're aware of, please post it. N.B. I know I can use Boolean.valueOf or Boolean.parseBoolean to convert a string literal into a boolean, but I'm just looking to discuss the API design.

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• Just 2 free months 2 learn or improve my skills

  - by microspino

  On the 30 of June I will leave my every day work to start as freelance developer. I'd like to set a period of 2 months apart to improve my dev skills. At work I code in C# and during my spare time I enjoyed building Ruby on Rails web applications and creating some Arduino prototypes. I'm something more than junior but I don't feel really a senior developer because I never had a big corporate project built and designed by me with help of other juniors (although I don't think this is really a good definiton of a "senior", It helps describing my feelings). Using a scale from 0 (ignorant) to 10 (proficient like a "samurai") the list below describes my skills that I would like to improve with just 2 months. I've already bought some nice and updated books on all the subjects hereunder: The order doesn't matter C = 1 C# & .Net = 6 Arduino & Processing = 2 Ruby = 5 Rails = 5 HTML/XHTML/CSS = 9 Javascript = 6 Objective-C/iPhone dev = 2 Python = 4 Django = 4 Desing Patterns = 3 Algorythms = 3 Git = 5 I haven't included SQL or Databases in general nor Networking because I spent 10 years working in the past with them and I feel pretty solid for now. As an aside, I've made up some interest in Redis, Node.js, HTML5 reading about them on the web. After two months, since I have to pay my bills, I could go searching for some new job. If learning and developing were really good maybe I could also invest on something I gave birth during them. Can You give me some piece of advice on which you think It's better to improve or develop a learning project on (something like a "summer of code" thing)? The all point Is to see my weeknesses and work on them.

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• regressions with many nested categorical covariates

  - by eric

  I have a few hundred thousand measurements where the dependent variable is a probability, and would like to use logistic regression. However, the covariates I have are all categorical, and worse, are all nested. By this I mean that if a certain measurement has "city - Phoenix" then obviously it is certain to have "state - Arizona" and "country - U.S." I have four such factors - the most granular has some 20k levels, but if need be I could do without that one, I think. I also have a few non-nested categorical covariates (only four or so, with maybe three different levels each). What I am most interested in is prediction - given a new observation in some city, I would like to know the relevant probability/dependent variable. I am not interested as much in the related inferential machinery - standard deviations, etc - at least as of now. I am hoping I can afford to be sloppy. However, I would love to have that information unless it requires methods that are more computationally expensive. Does anyone have any advice on how to attack this? I have looked into mixed effects, but am not sure it is what I am looking for.

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• Facebook-ios-sdk with embedded UIWebView

  - by Benchtop Creative

  I'm working with the new facebook-ios-sdk and have successfully integrated the api into my native app. I am able to authenticate a user and properly setup permissions using a popup dialog with the ios-sdk classes. For a portion of my app I need to use the facebook connection within a UIWebView, using javascript and html to process data within the webview. Given that the user is already logged in and authenticated via the above routine, I would have assumed that the UIWebView would share those credentials, or that there would at least be some way to pass or assign the credentials to the webview. Unfortunately, I found this earlier post which seems to suggest that this scheme doesn't quite work (iOS - being logged-in in a webView after logging in with the SDK). Has anyone else encountered this and/or found a work around? This seems like it would be a fairly straightforward use case given that I'm not trying to launch mobile safari or something like that - it's all within the same native app. It just seems like there must be some sort of easy trick or setting that I'm missing. Maybe somehow setting cookies in the new UIWebView? or something like this?

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• How do I bind to a custom view in Cocoa using Xcode 4?

  - by Newt

  I'm a beginner when it comes to writing Mac apps and working with Cocoa, so please forgive my ignorance. I'm looking to create a custom view, that exposes some properties, which I can then bind to an NSObjectController. Since it's a custom view, the Bindings Inspector obviously doesn't list any of the properties I've added to the view that I can then bind to using Interface Builder. After turning to the Stackoverflow/Google for help, I've stumbled across a couple of possible solutions, but neither seem to be quite right for my situation. The first suggested creating an IBPlugin, which would then mean my bindings would be available in the Bindings Inspector. I could then bind the view to the controller using IB. Apparently IBPlugins aren't supported in Xcode 4, so that one's out the window. I'm also assuming (maybe wrongly) that IBPlugins are no longer supported because there's a better way of doing such things these days? The second option was to bind the controller to the view programmatically. I'm a bit confused as to exactly how I would achieve this. Would it require subclassing NSObjectController so I can add the calls to bind to the view? Would I need to add anything to the view to support this? Some examples I've seen say you'd need to override the bind method, and others say you don't. Also, I've noticed that some example custom views call [self exposeBinding:@"bindingName"] in the initializer. From what I gather from various sources, this is something that's related to IBPlugins and isn't something I need to do if I'm not using them. Is that correct? I've found a post on Stackoverflow here which seems to discuss something very similar to my problem, but there wasn't any clear winner as to the best answer. The last comment by noa on 12th Sept seems interesting, although they mention you should be calling exposeBinding:. Is this comment along the right track? Is the call to exposeBinding really necessary? Apologies for any dumb questions. Any help greatly appreciated.

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• "no inclosing instance error " while getting top term frequencies for document from Lucene index

  - by Julia

  Hello ! I am trying to get the most occurring term frequencies for every particular document in Lucene index. I am trying to set the treshold of top occuring terms that I care about, maybe 20 However, I am getting the "no inclosing instance of type DisplayTermVectors is accessible" when calling Comparator... So to this function I pass vector of every document and max top terms i would like to know protected static Collection getTopTerms(TermFreqVector tfv, int maxTerms){ String[] terms = tfv.getTerms(); int[] tFreqs = tfv.getTermFrequencies(); List result = new ArrayList(terms.length); for (int i = 0; i < tFreqs.length; i++) { TermFrq tf = new TermFrq(terms[i], tFreqs[i]); result.add(tf); } Collections.sort(result, new FreqComparator()); if(maxTerms < result.size()){ result = result.subList(0, maxTerms); } return result; } /Class for objects to hold the term/freq pairs/ static class TermFrq{ private String term; private int freq; public TermFrq(String term,int freq){ this.term = term; this.freq = freq; } public String getTerm(){ return this.term; } public int getFreq(){ return this.freq; } } /*Comparator to compare the objects by the frequency*/ class FreqComparator implements Comparator{ public int compare(Object pair1, Object pair2){ int f1 = ((TermFrq)pair1).getFreq(); int f2 = ((TermFrq)pair2).getFreq(); if(f1 > f2) return 1; else if(f1 < f2) return -1; else return 0; } } Explanations and corrections i will very much appreciate, and also if someone else had experience with term frequency extraction and did it better way, I am opened to all suggestions! Please help!!!! Thanx!

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• .NET MVC: How to fix Visual Studio's lack of awareness of CSS classes in partial views?

  - by Mega Matt

  Hi all, This has been sort of an annoyance for me for a while. I make pretty heavy use of partial views in MVC, and am using Visual Studio 2008 to develop. The problem is that when I give html elements a class in a partial view (<div class="someClass">), it will underline them in green like it doesn't know what they are. I realize this is because I'm in a partial view, and haven't put link tags anywhere in that file for it to know where the CSS is (the link tags are in the main view that renders the partial view). The CSS still works fine on my site because the browser will render all views as one long html page anyway, but it's really annoying to look through my partial views and see all of my classes underlined in green. Is there a way that I can still tell Visual Studio that those classes exist somewhere, from the partial view? I figured there has to be a way to let it know, but am not sure what it is. Maybe a way to import the stylesheets from the parent view? Thanks for your help.

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• What should I do with an over-bloated select-box/drop-down

  - by Tristan Havelick

  All web developers run into this problem when the amount of data in their project grows, and I have yet to see a definitive, intuitive best practice for solving it. When you start a project, you often create forms with tags to help pick related objects for one-to-many relationships. For instance, I might have a system with Neighbors and each Neighbor belongs to a Neighborhood. In version 1 of the application I create an edit user form that has a drop down for selecting users, that simply lists the 5 possible neighborhoods in my geographically limited application. In the beginning, this works great. So long as I have maybe 100 records or less, my select box will load quickly, and be fairly easy to use. However, lets say my application takes off and goes national. Instead of 5 neighborhoods I have 10,000. Suddenly my little drop-down takes forever to load, and once it loads, its hard to find your neighborhood in the massive alphabetically sorted list. Now, in this particular situation, having hierarchical data, and letting users drill down using several dynamically generated drop downs would probably work okay. However, what is the best solution when the objects/records being selected are not hierarchical in nature? In the past, of done this with a popup with a search box, and a list, but this seems clunky and dated. In today's web 2.0 world, what is a good way to find one object amongst many for ones forms? I've considered using an Ajaxifed search box, but this seems to work best for free text, and falls apart a little when the data to be saved is just a reference to another object or record. Feel free to cite specific libraries with generic solutions to this problem, or simply share what you have done in your projects in a more general way

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• Behavior difference between UIView.subviews and [NSView subviews]

  - by zpasternack

  I have a piece of code in an iPhone app, which removes all subviews from a UIView subclass. It looks like this: NSArray* subViews = self.subviews; for( UIView *aView in subViews ) { [aView removeFromSuperview]; } This works fine. In fact, I never really gave it much thought until I tried nearly the same thing in a Mac OS X app (from an NSView subclass): NSArray* subViews = [self subviews]; for( NSView *aView in subViews ) { [aView removeFromSuperview]; } That totally doesn’t work. Specifically, at runtime, I get this: *** Collection <NSCFArray: 0x1005208a0> was mutated while being enumerated. I ended up doing it like so: NSArray* subViews = [[self subviews] copy]; for( NSView *aView in subViews ) { [aView removeFromSuperview]; } [subViews release]; That's fine. What’s bugging me, though, is why does it work on the iPhone? subviews is a copy property: @property(nonatomic,readonly,copy) NSArray *subviews; My first thought was, maybe @synthesize’d getters return a copy when the copy attribute is specified. The doc is clear on the semantics of copy for setters, but doesn’t appear to say either way for getters (or at least, it’s not apparent to me). And actually, doing a few tests of my own, this clearly does not seem to be the case. Which is good, I think returning a copy would be problematic, for a few reasons. So the question is: how does the above code work on the iPhone? NSView is clearly returning a pointer to the actual array of subviews, and perhaps UIView isn’t. Perhaps it’s simply an implementation detail of UIView, and I shouldn’t get worked up about it. Can anyone offer any insight?

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• Modify passed, nested dict/list

  - by Gerenuk

  I was thinking of writing a function to normalize some data. A simple approach is def normalize(l, aggregate=sum, norm_by=operator.truediv): aggregated=aggregate(l) for i in range(len(l)): l[i]=norm_by(l[i], aggregated) l=[1,2,3,4] normalize(l) l -> [0.1, 0.2, 0.3, 0.4] However for nested lists and dicts where I want to normalize over an inner index this doesnt work. I mean I'd like to get l=[[1,100],[2,100],[3,100],[4,100]] normalize(l, ?? ) l -> [[0.1,100],[0.2,100],[0.3,100],[0.4,100]] Any ideas how I could implement such a normalize function? Maybe it would be crazy cool to write normalize(l[...][0]) Is it possible to make this work?? Or any other ideas? Also not only lists but also dict could be nested. Hmm... EDIT: I just found out that numpy offers such a syntax (for lists however). Anyone know how I would implement the ellipsis trick myself?

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• UITableView reloaddata doesn't reload immediately

  - by D33

  Hi everyone. I'm trying to work with online data in my iPhone app. But I'm getting mad because of this: I have object for downloading data with NSURLConnection. Method starting the work with connection (and other stuff) in separate thread - [ NSThread detachNewThreadSelector:@selector( doConnectionInNewThread ) toTarget: self withObject: nil ]; When data are loaded (connectionDidFinishLoading) I give them to my viewController. This all stuff works fine. When I use breakpoints or NSLog I have the data ready to show in UITableView. When I call reloadData, nothing happens immediately. It reloads data after maybe 2 seconds (- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath is called after this delay). BUT when I slide the tableView, it reloads data immediately. So the connection and so on works fine but it just doesn't reload the data. Why? I thought it could be due to blocked mainThread by URLConnection. But now I use it in separate thread and it is still the same...

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• Survey statistic diagram ideas

  - by Nort

  Hey everyone, I've got some homework tasks in topic surveys and diagrams. The first task is to normalize the input of a survey, because the structure of the data is changing from time-to-time. So there are three types of surveys: static fields, where text is stored dynamic ones, where the user can select one option and multiselect fields, where the user can select multiple options So I'm not really a statistics guy, so I have really no idea what I can do with that incomming data. So the data I have is stored in an orbital XML file from there I can easily get how man times a survey was filled, and how many times a field was filled, so I can (for eg on a pie chart show the relation of filled or not filled). The second idea is to show the relation between the content of a multi option element using a bar chart or so. In case of the multi option elements I've got the idea to show data in implication of one option. But the question is, what could be shown? The other problem are the static elements (text fields and so). What data could be represented from a single field? The data in the XML field is collected from 2001 to 2005 So maybe I can work with the dates of the surveys, but as I said, i don't really know how to process the data, to collect as much data as possible.

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• do not allow integrated windows authentication *for one of the domains*

  - by MK

  We have an ASP.NET web application which uses integrated windows authentication. It is accessed by users from two domains, A and B. A is the primary domain and B is an older domain which is going away. Web application is authenticating users using a group policy which only exists in domain A. Every user in domain B has an account in domain A. The application lives in domain A. There was no trust between the domains. So users from domain A would get silently authenticated and logged into the site. Users from domain B didn't get authenticated automatically and were prompted with the IE popup, to which they authenticated using their domain A credentials and everything worked. Now somebody has set up a trust between the domains and users from domain B get authenticated silently to IIS, and then their login fails (no group policy). So the question is: can I either programmatically or in IIS configuration make it so that users from domain B still get prompted even though there is trust between the domains? Is there a way to tell the server where IIS is running to ignore the trust relationship maybe?

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• How to intercept touch events globally?

  - by mystify

  I have an view which is sometimes covered by some other views. However, if the user slides the finger across the screen, I want to slide that underlying view across the screen, too. I could start making custom views for all those covering subviews and forward all kinds of touch events, but that's somewhat cumbersome. Maybe there's some kind of notification or another way that a UIView or UIControl subclass can be aware of touch events happening right now, no matter where they are. In short: I need an UIView subclass or UIControl subclass which knows about any touch events happening on the entire screen. Or at least if tht's not possible, knowing about any touch events happening above itself in the same underlying superview. Another description: There are 20 views, all reside inside the same superview. The first view is covered by 19 others. But if the user slides across the screen, that first view must slide too, so it must be aware of touch events. Is there any better solution that making all 19 views forward touch events? (yes, all 19 views respond to touch events in this example)

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• Qt/C++ Error handling

  - by ShiGon

  I've been doing a lot of research about handling errors with Qt/C++ and I'm still as lost as when I started. Maybe I'm looking for an easy way out (like other languages provide). One, in particular, provides for an unhandled exception which I use religiously. When the program encounters a problem, it throws the unhandled exception so that I can create my own error report. That report gets sent from my customers machine to a server online which I then read later. The problem that I'm having with C++ is that any error handling that's done has to be thought of BEFORE hand (think try/catch or massive conditionals). In my experience, problems in code are not thought of before hand else there wouldn't be a problem to begin with. Writing a cross-platform application without a cross-platform error handling/reporting/trace mechanism is a little scary to me. My question is: Is there any kind of Qt or C++ Specific "catch-all" error trapping mechanism that I can use in my application so that, if something does go wrong I can, at least, write a report before it crashes?

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• Synchronous Android activities

  - by rayman

  Ive made mis-leading topic in my last question, so i open this new question to clear what I realy want. sorry for the inconvenience. I wanna run two system(Android) activities one after another in specific order from my main activity. now as we know, startActivity is an asynchronous operation, so i cant keep on a specific order. so i thought maybe I should try to do it with dialogBox in the middle but also running a dialogBox is an asynchronous. now as i said the activities which i try to run are Android activities, so i cant even start them with startActivityForResult (or mybe i can, but i dont get any result back to my main(calling) activity) Any tricks how could i manage with this issue? Some code: first activity: Intent intent = new Intent(); intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK); intent.setAction(Settings.ACTION_APPLICATION_SETTINGS); startActivity(intent); second activity: Intent intent = new Intent(Intent.ACTION_VIEW); intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK); intent.setDataAndType(Uri.fromFile(tmpPackageFile .getAbsoluteFile()), "application/vnd.android.package-archive"); startActivity(intent); as you can see, i dont have any access to those activites, i can just run thire intents from my main activity.

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• C++ Matrix class hierachy

  - by bpw1621

  Should a matrix software library have a root class (e.g., MatrixBase) from which more specialized (or more constrained) matrix classes (e.g., SparseMatrix, UpperTriangluarMatrix, etc.) derive? If so, should the derived classes be derived publicly/protectively/privately? If not, should they be composed with a implementation class encapsulating common functionality and be otherwise unrelated? Something else? I was having a conversation about this with a software developer colleague (I am not per se) who mentioned that it is a common programming design mistake to derive a more restricted class from a more general one (e.g., he used the example of how it was not a good idea to derive a Circle class from an Ellipse class as similar to the matrix design issue) even when it is true that a SparseMatrix "IS A" MatrixBase. The interface presented by both the base and derived classes should be the same for basic operations; for specialized operations, a derived class would have additional functionality that might not be possible to implement for an arbitrary MatrixBase object. For example, we can compute the cholesky decomposition only for a PositiveDefiniteMatrix class object; however, multiplication by a scalar should work the same way for both the base and derived classes. Also, even if the underlying data storage implementation differs the operator()(int,int) should work as expected for any type of matrix class. I have started looking at a few open-source matrix libraries and it appears like this is kind of a mixed bag (or maybe I'm looking at a mixed bag of libraries). I am planning on helping out with a refactoring of a math library where this has been a point of contention and I'd like to have opinions (that is unless there really is an objective right answer to this question) as to what design philosophy would be best and what are the pros and cons to any reasonable approach.

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• Queuing using table or MSMQ?

  - by Lieven Cardoen

  A part of the application I'm working on is an swf that shows a test with some 80 questions. Each question is saved to a sql server through WebORB and asp.net. If a candidate finisheds the test, the session needs to be validated. Problem now is that sometimes 350 candidates finish their test at the same moment, and cpu on webserver and sql server explodes (350 validations concurrently). Now, how would I implement queuing here? In the database, there's a table that has a record for each session. One column holds the status. 1 is finished, 2 is validated. I could implement queuing in two ways (as I see it, maybe you have other propositions): A process that checks the table for records with status 1. If it finds one, it validates the session. So, sessions are validated one after one. If a candidate finishes its session, a message is sent to a MSMQ queue. Another process listens to the queue and validates sessions one after one. Now, What would be the best approach? Where do you start the process that will validate sessions? In your global.asax (application_start)? As a windows service? As an exe on the root of the website that is started in application_start? To me, using the table and looking for records with status 1 seems the easiest way.

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• iPhone: Low memory crash...

  - by MacTouch

  Once again I'm hunting memory leaks and other crazy mistakes in my code. :) I have a cache with frequently used files (images, data records etc. with a TTL of about one week and a size limited cache (100MB)). There are sometimes more then 15000 files in a directory. On application exit the cache writes an control file with the current cache size along with other useful information. If the applications crashes for some reason (sh.. happens sometimes) I have in such case to calculate the size of all files on application start to make sure I know the cache size. My app crashes at this point because of low memory and I have no clue why. Memory leak detector does not show any leaks at all. I do not see any too. What's wrong with the code below? Is there any other fast way to calculate the total size of all files within a directory on iPhone? Maybe without to enumerate the whole contents of the directory? The code is executed on the main thread. NSUInteger result = 0; NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; NSDirectoryEnumerator *dirEnum = [[[NSFileManager defaultManager] enumeratorAtPath:path] retain]; int i = 0; while ([dirEnum nextObject]) { NSDictionary *attributes = [dirEnum fileAttributes]; NSNumber* fileSize = [attributes objectForKey:NSFileSize]; result += [fileSize unsignedIntValue]; if (++i % 500 == 0) { // I tried lower values too [pool drain]; } } [dirEnum release]; dirEnum = nil; [pool release]; pool = nil; Thanks, MacTouch

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