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  • Valueurl Binding On Large Arrays Causes Sluggish User Interface

    - by Hooligancat
    I have a large data set (some 3500 objects) that returns from a remote server via HTTP. Currently the data is being presented in an NSCollectionView. One aspect of the data is a path pack to the server for a small image that represents the data (think thumbnail for simplicity). Bindings works fantastically for the data that is already returned, and binding the image via a valueurl binding is easy to do. However, the user interface is very sluggish when scrolling through the data set - which makes me think that the NSCollectionView is retrieving all the image data instead of just the image data used to display the currently viewable images. I was under the impression that Cocoa controls were smart enough to only retrieve data for the information that is actually being output to the user interface through lazy loading. This certainly seems to be the case with NSTableView - but I could be misguided on this thought. Should valueurl binding act lazily and, moreover, should it act lazily in an NSCollectionView? I could create a caching mechanism (in fact I already have such a thing in place for another application - see my post here if you are interested http://stackoverflow.com/questions/1740209/populating-nsimage-with-data-from-an-asynchronous-nsurlconnection) but I really don't want to go this route if I don't have to for this specific implementation as the user could potentially change data sets often and may only want small sub-sets of the data. Any suggested approaches? Thanks!

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  • getting proxies of the correct type in nhibernate

    - by Nir
    I have a problem with uninitialized proxies in nhibernate The Domain Model Let's say I have two parallel class hierarchies: Animal, Dog, Cat and AnimalOwner, DogOwner, CatOwner where Dog and Cat both inherit from Animal and DogOwner and CatOwner both inherit from AnimalOwner. AnimalOwner has a reference of type Animal called OwnedAnimal. Here are the classes in the example: public abstract class Animal { // some properties } public class Dog : Animal { // some more properties } public class Cat : Animal { // some more properties } public class AnimalOwner { public virtual Animal OwnedAnimal {get;set;} // more properties... } public class DogOwner : AnimalOwner { // even more properties } public class CatOwner : AnimalOwner { // even more properties } The classes have proper nhibernate mapping, all properties are persistent and everything that can be lazy loaded is lazy loaded. The application business logic only let you to set a Dog in a DogOwner and a Cat in a CatOwner. The Problem I have code like this: public void ProcessDogOwner(DogOwner owner) { Dog dog = (Dog)owner.OwnedAnimal; .... } This method can be called by many diffrent methods, in most cases the dog is already in memory and everything is ok, but rarely the dog isn't already in memory - in this case I get an nhibernate "uninitialized proxy" but the cast throws an exception because nhibernate genrates a proxy for Animal and not for Dog. I understand that this is how nhibernate works, but I need to know the type without loading the object - or, more correctly I need the uninitialized proxy to be a proxy of Cat or Dog and not a proxy of Animal. Constraints I can't change the domain model, the model is handed to me by another department, I tried to get them to change the model and failed. The actual model is much more complicated then the example and the classes have many references between them, using eager loading or adding joins to the queries is out of the question for performance reasons. I have full control of the source code, the hbm mapping and the database schema and I can change them any way I want (as long as I don't change the relationships between the model classes). I have many methods like the one in the example and I don't want to modify all of them. Thanks, Nir

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  • I deleted a full set of columns in a save, but have the original larger sheet, Can I get that back?

    - by Ben Henley
    I have an original sheet that has over 39000 lines in it. I knocked it down to 1800 lines that I want to improt into my database, however. The Dumb#$$ that I am, I selected only the visible cells and killed like 10 columns that I need. Is there a way to compare to the original sheet using a specific column... i.e. SKU and pull the data from the origianal to put back in the missing columns or do I have to just re-edit the whole thing down again. Please help as this takes a good day or two to minimize. Any and all help is much appreciated. Below is the column list on the edited sheet vs. the original sheet. SKU DESCRIPTION VENDOR PART # RETAIL UNIT CONVERSION RETAIL U/M RETAIL DEPARTMENT VENDOR NAME SELL PACK QUANTITY BREAK SELL PACK FLAG BLISH VENDOR # FINE LINE CLASS ITEM ACTION FLAG PRIMARY UPC STOCK U/M WEIGHT LENGTH WIDTH HEIGHT SHIP-VIA EXCLUSION HAZARDOUS CODE PRICE SUGGESTED RETAIL SKU DESCRIPTION RETAIL UNIT CONVERSION RETAIL U/M RETAIL DEPARTMENT VENDOR NAME SELL PACK QUANTITY BREAK SELL PACK FLAG FINE LINE CLASS HAZARDOUS CODE PRICE SUGGESTED RETAIL RETAIL SENSITIVITY CODE 2ND UPC CODE 3RD UPC CODE 4TH UPC CODE HEADLINE BULLET #1 BULLET #2 BULLET #3 BULLET #4 BULLET #5 BULLET #6 BULLET #7 BULLET #8 BULLET #9 SIZE COLOR CASE QUANTITY PRODUCT LINE Thanks, Ben

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  • PHP Switch and Login

    - by Steve Rivera
    I'm fairly new with PHP and I am messing around with a login/registration system. I setup my sample website using a PHP-SWITCH script I found a while back: <?php switch($_GET['id']) { default: include('home.php'); /* LOGIN PAGES */ break; case "register_form": include ('includes/user_system/register_form.php'); } ? On the registration page the form links to my "register.php" which checks the validity of the form and to check for any blank fields and so on. "register.php" is supposed to refresh the page and add a reason to what the user did wrong when submitting the form. On my "register_form.php" page, which holds the actual form. This field is hidden until the user makes a mistake. <?php if (isset($reg_error)) { ?> , please try again. My "register.php" checks the form for all the errors. Here's the bit of code that will refresh the page with the reason for the error: // Check if any of the fields are missing if (empty($_POST['username']) || empty($_POST['password']) || empty($_POST['confirmpass'])) { // Reshow the form with an error $reg_error = 'One or more fields missing'; include 'register_form.php'; Now after I submit the form without any fields filled out I get the error code, but it refreshes to the actual "register_form.php". The problem with this is that because of my PHP-SWITCH script (helps me manage the site a lot easier) I don't have any formatting on that page. The actual URL to my "register_form.php" would be: "index.php?id=register_form.php". Now I have tried several different things such as changing it to: include 'index.php?id=register_form.php' And also changing it to: header(location:index.php?id=register_form.php') Unfortunately all this does is refresh the page without the reason for the error. I know this can be easily solved by just adding a Javascript Validator but I'd like to know if it is possible to refresh the page with the error using either "include" or "header()" while having a PHP-SWITCH script on the website.

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  • What's the Matlab equivalent of NULL, when it's calling COM/ActiveX methods?

    - by David M
    Hi, I maintain a program which can be automated via COM. Generally customers use VBS to do their scripting, but we have a couple of customers who use Matlab's ActiveX support and are having trouble calling COM object methods with a NULL parameter. They've asked how they do this in Matlab - and I've been scouring Mathworks' COM/ActiveX documentation for a day or so now and can't figure it out. Their example code might look something like this: function do_something() OurAppInstance = actxserver('Foo.Application'); OurAppInstance.Method('Hello', NULL) end where NULL is where in another language, we'd write NULL or nil or Nothing, or, of course, pass in an object. The problem is this is optional (and these are implemented as optional parameters in most, but not all, cases) - these methods expect to get NULL quite often. They tell me they've tried [] (which from my reading seemed the most likely) as well as '', Nothing, 'Nothing', None, Null, and 0. I have no idea how many of those are even valid Matlab keywords - certainly none work in this case. Can anyone help? What's Matlab's syntax for a null pointer / object for use as a COM method parameter? Update: Thanks for all the replies so far! Unfortunately, none of the answers seem to work, not even libpointer. The error is the same in all cases: Error: Type mismatch, argument 2 This parameter in the COM type library is described in RIDL as: HRESULT _stdcall OurMethod([in] BSTR strParamOne, [in, optional] OurCoClass* oParamTwo, [out, retval] VARIANT_BOOL* bResult); The coclass in question implements a single interface descending from IDispatch.

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  • PostgreSQL insert on primary key failing with contention, even at serializable level

    - by Steven Schlansker
    I'm trying to insert or update data in a PostgreSQL db. The simplest case is a key-value pairing (the actual data is more complicated, but this is the smallest clear example) When you set a value, I'd like it to insert if the key is not there, otherwise update. Sadly Postgres does not have an insert or update statement, so I have to emulate it myself. I've been working with the idea of basically SELECTing whether the key exists, and then running the appropriate INSERT or UPDATE. Now clearly this needs to be be in a transaction or all manner of bad things could happen. However, this is not working exactly how I'd like it to - I understand that there are limitations to serializable transactions, but I'm not sure how to work around this one. Here's the situation - ab: => set transaction isolation level serializable; a: => select count(1) from table where id=1; --> 0 b: => select count(1) from table where id=1; --> 0 a: => insert into table values(1); --> 1 b: => insert into table values(1); --> ERROR: duplicate key value violates unique constraint "serial_test_pkey" Now I would expect it to throw the usual "couldn't commit due to concurrent update" but I'm guessing since the inserts are different "rows" this does not happen. Is there an easy way to work around this?

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  • Dojo dialog, the iPad and the virtual keyboard issue

    - by Chris Butler
    Recently, I have been working on a project where the interface should work for desktop and tablets (in particular the iPad). One issue I am coming across is with a Dojo dialog on the iPad when text entry is taking place. Basically here is what happens: Load Dojo interface with buttons on iPad - OK Press button (touch) to show dialog (90% height and width) - OK Click on text box (touch) like DateTextBox or TimeTextBox - OK, the virtual keyboard is opened Click the date or time I want in the UI (touch) - OK, but I can't see all of the options since it is longer than the screen size... Try to scroll down (swipe up with two fingers or click 'next' in the keyboard) - not OK and the dialog repositions itself to have it's top at the top of the viewport area. Basically, the issue is that the dialog keeps trying to reposition itself. Am I able to stop dialog resizing and positioning if I catch the window onResize events? Does anyone else have this issue with the iPad and Dojo dialogs? Also, I found this StackOverflow topic on detecting the virtual keyboard, but it wasn't much help in this case... http://stackoverflow.com/questions/2593139/ipad-web-app-detect-virtual-keyboard-using-javascript-in-safari Thanks!

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  • Inserting a ContentControl after another ContentControl

    - by Markus Roth
    In our VSTO Word 2010 Addin, we are trying to insert a RichTextControl after a given other ContentControl. We have tried this: public ContentControl AddContentControl(WdContentControlType type, int position) { Paragraph paragraphBefore = null; if (position == 0) { if (WordDocument.Paragraphs.Count == 0) { WordDocument.Paragraphs.Add(); } paragraphBefore = WordDocument.Paragraphs.First; } else { paragraphBefore = Controls.ElementAt(position - 1).Range.Paragraphs.Last; } object start = paragraphBefore.Range.End; object end = paragraphBefore.Range.End + 1; paragraphBefore.Range.InsertParagraphAfter(); Range rangeToUse = WordDocument.Range(ref start, ref end); ContentControl newControl = _ContentControl = _WordDocument.ContentControls.Add(type, rangeToInsert); Controls.Insert(position, newControl); OnNewContentControl(newControl, position); return newControl.ContentControl; } which works fine, unless the control that is before the one we want to insert has an empty paragraph at the end. If that is the case, the new ContentControl is inserted within the last control. How can we avoid this?

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  • Join + IEqualityComparer<T> and HashCode

    - by Jesus Rodriguez
    Im writing my own LINQ reference but Im getting troubles with some of the more complicated operators implementations. There is a Join implementation that takes a IEqualityComparer Im getting just crazy. Im trying to understand it first before I write (obviously) Image this two lists: List<string> initials = new List<string> {"A", "B", "C", "D", "E"}; List<string> words = new List<string> {"Ant", "Crawl", "Pig", "Boat", "Elephant", "Arc"}; Nothing weird here. I want to join both lists by the Initial, something like: Initial=A Word=Ant Initial=A Word=Arc Initial=B Word=Boat ... I need a comparator, I wrote this: public class InitialComparator : IEqualityComparer<string> { public bool Equals(string x, string y) { return x.StartsWith(y); } public int GetHashCode(string obj) { return obj[0].GetHashCode(); } } The Join itself: var blah = initials.Join(words, initial => initial, word => word, (initial, word) => new {Initial = initial, Word = word}, new InitialComparator()); It's the first time Im using HashCodes, after a good session of debugging I see that every word go to the comparator and look at its HashCode, if another word has the same HashCode it calls equals. Since I want to compare just the initial I though that I just need the first letter Hash (Am I wrong?) The thing is that this is not working correctly. Its says that "Ant" and "Arc" are equals, Ok, its comparing every word in the same list or not, But it adds only the last word it finds, in this case Arc, ignoring Ant and Ant is equals to "A" too... If I put "Ant" and "Ant" it add both. In short, What is the way of doing something like that? I know that Im doing something wrong. Thank you.

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  • CreateDelegate with unknown types

    - by Giorgi
    Hello, I am trying to create Delegate for reading/writing properties of unknown type of class at runtime. I have a generic class Main<T> and a method which looks like this: Delegate.CreateDelegate(typeof(Func<T, object>), get) where get is a MethodInfo of the property that should be read. The problem is that when the property returns int (I guess this happens for value types) the above code throws ArgumentException because the method cannot be bound. In case of string it works well. To solve the problem I changed the code so that corresponding Delegate type is generated by using MakeGenericType. So now the code is: Type func = typeof(Func<,>); Type generic = func.MakeGenericType(typeof(T), get.ReturnType); var result = Delegate.CreateDelegate(generic, get) The problem now is that the created delegate instance of generic so I have to use DynamicInvoke which would be as slow as using pure reflection to read the field. So my question is why is that the first snippet of code fails with value types. According to MSDN it should work as it says that The return type of a delegate is compatible with the return type of a method if the return type of the method is more restrictive than the return type of the delegate and how to execute the delegate in the second snippet so that it is faster than reflection. Thanks.

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  • How to use boost::bind with non-copyable params, for example boost::promise ?

    - by zhengxi
    Some C++ objects have no copy constructor, but have move constructor. For example, boost::promise. How can I bind those objects using their move constructors ? #include <boost/thread.hpp> void fullfil_1(boost::promise<int>& prom, int x) { prom.set_value(x); } boost::function<void()> get_functor() { // boost::promise is not copyable, but movable boost::promise<int> pi; // compilation error boost::function<void()> f_set_one = boost::bind(&fullfil_1, pi, 1); // compilation error as well boost::function<void()> f_set_one = boost::bind(&fullfil_1, std::move(pi), 1); // PS. I know, it is possible to bind a pointer to the object instead of // the object itself. But it is weird solution, in this case I will have // to take cake about lifetime of the object instead of delegating that to // boost::bind (by moving object into boost::function object) // // weird: pi will be destroyed on leaving the scope boost::function<void()> f_set_one = boost::bind(&fullfil_1, boost::ref(pi), 1); return f_set_one; }

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  • How to solve timing problems in automated UI tests with C# and Visual Studio?

    - by Lernkurve
    Question What is the standard approach to solve timing problems in automated UI tests? Concrete example I am using Visual Studio 2010 and Team Foundation Server 2010 to create automated UI tests and want to check whether my application has really stopped running: [TestMethod] public void MyTestMethod() { Assert.IsTrue(!IsMyAppRunning(), "App shouldn't be running, but is."); StartMyApp(); Assert.IsTrue(IsMyAppRunning(), "App should have been started and should be running now."); StopMyApp(); //Pause(500); Assert.IsTrue(!IsMyAppRunning(), "App was stopped and shouldn't be running anymore."); } private bool IsMyAppRunning() { foreach (Process runningProcesse in Process.GetProcesses()) { if (runningProcesse.ProcessName.Equals("Myapp")) { return true; } } return false; } private void Pause(int pauseTimeInMilliseconds) { System.Threading.Thread.Sleep(pauseTimeInMilliseconds); } StartMyApp() and StopMyApp() have been recorded with MS Test Manager 2010 and reside in UIMap.uitest. The last assert fails because the assertion is executed while my application is still in the process of shutting down. If I put a delay after StopApp() the test case passes. The above is just an example to explain my problem. What is the standard approach to solve these kinds of timing issues? One idea would be to wait with the assertion until I get some event notification that my app has been stopped.

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  • PHP OOP: Providing Domain Entities with "Identity"

    - by sunwukung
    Bit of an abstract problem here. I'm experimenting with the Domain Model pattern, and barring my other tussles with dependencies - I need some advice on generating Identity for use in an Identity Map. In most examples for the Data Mapper pattern I've seen (including the one outlined in this book: http://apress.com/book/view/9781590599099) - the user appears to manually set the identity for a given Domain Object using a setter: $UserMapper = new UserMapper; //returns a fully formed user object from record sets $User = $UserMapper->find(1); //returns an empty object with appropriate properties for completion $UserBlank = $UserMapper->get(); $UserBlank->setId(); $UserBlank->setOtherProperties(); Now, I don't know if I'm reading the examples wrong - but in the first $User object, the $id property is retrieved from the data store (I'm assuming $id represents a row id). In the latter case, however, how can you set the $id for an object if it has not yet acquired one from the data store? The problem is generating a valid "identity" for the object so that it can be maintained via an Identity Map - so generating an arbitrary integer doesn't solve it. My current thinking is to nominate different fields for identity (i.e. email) and demanding their presence in generating blank Domain Objects. Alternatively, demanding all objects be fully formed, and using all properties as their identity...hardly efficient. (Or alternatively, dump the Domain Model concept and return to DBAL/DAO/Transaction Scripts...which is seeming increasingly elegant compared to the ORM implementations I've seen...)

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  • Calling a SLSB with Seam security from a servlet

    - by wilth
    Hello, I have an existing application written in SEAM that uses SEAM Security (http://docs.jboss.org/seam/2.1.1.GA/reference/en-US/html/security.html). In a stateless EJB, I might find something like this: @In Identity identity; ... if(identity.hasRole("admin")) throw new AuthException(); As far as I understand, Seam injects the Identity object from the SessionContext of the servlet that invokes the EJB (this happens "behind the scenes", since Seam doesn't really use servlets) and removes it after the call. Is this correct? Is it now possible to access this EJB from another servlet (in this case, that servlet is the server side of a GWT application)? Do I have to "inject" the correct Identity instance? If I don't do anything, Seam injects an instance, but doesn't correctly correlate the sessions and instances of Identity (so the instances of Identity are shared between sessions and sometimes calls get new instances etc.). Any help and pointers are very welcome - thanks! Technology: EJB3, Seam 2.1.2. The servlets are actually the server-side of a GWT app, although I don't think this matters much. I'm using JBoss 5.

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  • DAL Layer : EF 4.0 or Normal Data access layer with Stored Procedure

    - by Harryboy
    Hello Experts, Application : I am working on one mid-large size application which will be used as a product, we need to decide on our DAL layer. Application UI is in Silverlight and DAL layer is going to be behind service layer. We are also moving ahead with domain model, so our DB tables and domain classes are not having same structure. So patterns like Data Mapper and Repository will definitely come into picture. I need to design DAL Layer considering below mentioned factors in priority manner Speed of Development with above average performance Maintenance Future support and stability of the technology Performance Limitation : 1) As we need to strictly go ahead with microsoft, we can not use NHibernate or any other ORM except EF 4.0 2) We can use any code generation tool (Should be Open source or very cheap) but it should only generate code in .Net, so there would not be any licensing issue on per copy basis. Questions I read so many articles about EF 4.0, on outset it looks like that it is still lacking in features from NHibernate but it is considerably better then EF 1.0 So, Do you people feel that we should go ahead with EF 4.0 or we should stick to ADO .Net and use any code geneartion tool like code smith or any other you feel best Also i need to answer questions like what time it will take to port application from EF 4.0 to ADO .Net if in future we stuck up with EF 4.0 for some features or we are having serious performance issue. In reverse case if we go ahead and choose ADO .Net then what time it will take to swith to EF 4.0 Lastly..as i was going through the article i found the code only approach (with POCO classes) seems to be best suited for our requirement as switching is really easy from one technology to other. Please share your thoughts on the same and please guide on the above questions

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  • asp.net multiligual website culture settings

    - by Hemant Kothiyal
    Hi, In asp.net multilingual website in english Uk and swedish, i have three rsources file 1. en-GB.resx 2. sv-SE.resx 3. Culture neutral file. I have create one base class and all pages is inherited from that class. There i write following lines to set UICULTURE and culture 1. Thread.CurrentThread.CurrentUICulture = CultureInfo.CurrentUICulture.Name; 2. Thread.CurrentThread.CurrentCulture = CultureInfo.CurrentCulture.Name; Question: Suppose my browser language is Swedish(sv-SE) then this code will run because it find CurrentUICulture and CurrentCulture values as sv-SE. Now if suppose browser language is Swedish(sv) only, in that case values will be set as CurrentUICulture = sv; and CurrentCulture = sv-SE Now the problem is that user can able to view all text in Culture neutral resource file that i kept as english while all decimal saperators, currency and other will be appear in swedish. It looks confusing to usr. What would be right approach. I am thinking following solution. Please correct me? 1. i can create extra resource file for sv also. 2. I check value of CurrentUICulture in base class and if it is sv then replace it with sv-SE Please correct me which one is right approach or Is there any other good way of doing?

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  • RESTful design, how to name pages outside CRUD et al?

    - by sscirrus
    Hi all, I'm working on a site that has quite a few pages that fall outside my limited understanding of RESTful design, which is essentially: Create, Read, Update, Delete, Show, List Here's the question: what is a good system for labeling actions/routes when a page doesn't neatly fall into CRUD/show/list? Some of my pages have info about multiple tables at once. I am building a site that gives some customers a 'home base' after they log on. It does NOT give them any information about themselves so it shouldn't be, for example, /customers/show/1. It does have information about companies, but there are other pages on the site that do that differently. What do you do when you have these situations? This 'home-base' is shown to customers and it mainly has info about companies (but not uniquely so). Second case: I have a table called 'Matchings' in between customers and companies. These matchings are accessed in completely different ways on different parts of the site (different layouts, different CSS sheets, different types of users accessing them, etc. They can't ALL be matchings/show. What's the best way to label the others? Thanks very much. =)

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  • Parsing basic math equations for children's educational software?

    - by Simucal
    Inspired by a recent TED talk, I want to write a small piece of educational software. The researcher created little miniature computers in the shape of blocks called "Siftables". [David Merril, inventor - with Siftables in the background.] There were many applications he used the blocks in but my favorite was when each block was a number or basic operation symbol. You could then re-arrange the blocks of numbers or operation symbols in a line, and it would display an answer on another siftable block. So, I've decided I wanted to implemented a software version of "Math Siftables" on a limited scale as my final project for a CS course I'm taking. What is the generally accepted way for parsing and interpreting a string of math expressions, and if they are valid, perform the operation? Is this a case where I should implement a full parser/lexer? I would imagine interpreting basic math expressions would be a semi-common problem in computer science so I'm looking for the right way to approach this. For example, if my Math Siftable blocks where arranged like: [1] [+] [2] This would be a valid sequence and I would perform the necessary operation to arrive at "3". However, if the child were to drag several operation blocks together such as: [2] [\] [\] [5] It would obviously be invalid. Ultimately, I want to be able to parse and interpret any number of chains of operations with the blocks that the user can drag together. Can anyone explain to me or point me to resources for parsing basic math expressions? I'd prefer as much of a language agnostic answer as possible.

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  • HttpURLConnection: What's the deal with having to read the whole response?

    - by stormin986
    My current problem is very similar to this one. I have a downloadFile(URL) function that creates a new HttpURLConnection, opens it, reads it, returns the results. When I call this function on the same URL multiple times, the second time around it almost always returns a response code of -1 (But throws no exception!!!). The top answer in that question is very helpful, but there are a few things I'm trying to understand. So, if setting http.keepAlive to false solves the problem, it indicates what exactly? That the server is responding in a way that violates the http protocol? Or more likely, my code is violating the protocol in some way? What will the trace tell me? What should I look for? And what's the deal with this: You need to read everything from error stream. Otherwise, it's going to confuse next connection and that's the cause of -1. Does this mean if the response is some type of error (which would be what response code(s)?), the stream HAS to be fully read? Also, every time I am attempting an http request I am basically creating a new connection, and then disconnect()ing it at the end. However, in my case I'm not getting a 401 or whatever. It's always a 200. But my second connection almost always fails. Does this mean there's some other data I should be reading that I'm not (in a similar manner that the error stream must be fully read)? Please help shed some light on this? I feel like there's some fundamental http protocol understanding I'm missing.

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  • Invert a string: Recursion vs iteration in javascript

    - by steweb
    Hi all, one month ago I've been interviewed by some google PTO members. One of the questions was: Invert a string recursively in js and explain the running time by big O notation this was my solution: function invert(s){ return (s.length > 1) ? s.charAt(s.length-1)+invert(s.substring(0,s.length-1)) : s; } Pretty simple, I think. And, about the big-o notation, I quickly answered O(n) as the running time depends linearly on the input. - Silence - and then, he asked me, what are the differences in terms of running time if you implement it by iteration? I replied that sometimes the compiler "translate" the recursion into iteration (some programming language course memories) so there are no differences about iteration and recursion in this case. Btw since I had no feedback about this particular question, and the interviewer didn't answer "ok" or "nope", I'd like to know if you maybe agree with me or if you can explain me whether there could be differences about the 2 kind of implementations. Thanks a lot and Regards!

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  • database schema eligible for delta synchronization

    - by WilliamLou
    it's a question for discussion only. Right now, I need to re-design a mysql database table. Basically, this table contains all the contract records I synchronized from another database. The contract record can be modified, deleted or users can add new contract records via GUI interface. At this stage, the table structure is exactly the same as the Contract info (column: serial number, expiry date etc.). In that case, I can only synchronize the whole table (delete all old records, replace with new ones). If I want to delta(only synchronize with modified, new, deleted records) synchronize the table, how should I change the database schema? here is the method I come up with, but I need your suggestions because I think it's a common scenario in database applications. 1)introduce a sequence number concept/column: for each sequence, mark the new added records, modified records, deleted records with this sequence number. By recording the last synchronized sequence number, only pass those records with higher sequence number; 2) because deleted contracts can be added back, and the original table has primary key constraints, should I create another table for those deleted records? or add a flag column to indicate if this contract has been deleted? I hope I explain my question clearly. Anyway, if you know any articles or your own suggestions about this, please let me know. Thanks!

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  • How to get rid of the GUI access from shared library.

    - by Inso Reiges
    Hello, In my project i have a shared library with cross-platform code that provides a very convenient abstraction for a number of its clients. To be more specific, this library provides data access to encrypted files generated by main application on a number of platforms. There is a great deal of complicated code there that implements cryptographic protocols and as such is very error-prone and should be shared as much as possible across clients and platforms. However parsing all this encrypted stuff requires asking user for a number of different secrets ones in a while. The secret can be either a password, a number of shared passwords or a public key file and this list is a hot target for extension in the future. I can't really ask the user for any of those secrets beforehand from main application, because i really don't know what i need to ask for until i start working with the encrypted data directly in the library code. So i will have to create dialogs and call them from the library code. However i really see this as a bad idea, because (among other things) there is a possibility of a windows service using it and services can't have GUI access. The question is, are there any known ways or patterns to get rid of the GUI calls that are suitable for my case? Thank you.

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  • Multhreading in Java

    - by Vijay Selvaraj
    I'm working with core java and IBM Websphere MQ 6.0. We have a standalone module say DBcomponent that hits the database and fetches a resultset based on the runtime query. The query is passed to the application via MQ messaging medium. We have a trigger configured for the queue which invokes the DBComponent whenever a message is available in the queue. The DBComponent consumes the message, constructs the query and returns the resultset to another queue. In this overall process we use log4j to log statements on a log file for auditing. The connection is pooled to the database using Apache pool. I am trying to check whether the log messages are logged correctly using a sample program. The program places the input message to the queue and checks for the logs in the log file. Its expected for the trigger method invocation to complete before i try to check for the message in log file, but every time my program to check for log message gets executed first leading my check to failure. Even if i introduce a Thread.sleep(time) doesn't solves the case. How can i make it to keep my method execution waiting until the trigger operation completes? Any suggestion will be helpful.

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  • Python: deleting rows in a text file

    - by Jenny
    A sample of the following text file i have is: > 1 -4.6 -4.6 -7.6 > > 2 -1.7 -3.8 -3.1 > > 3 -1.6 -1.6 -3.1 the data is separated by tabs in the text file and the first column indicates the position. I need to iterate through every value in the text file apart from column 0 and find the lowest value. once the lowest value has been found that value needs to be written to a new text file along with the column name and position. Column 0 has the name "position" Column 1 "fifteen", column 2 "sixteen" and column 3 "seventeen" for example the lowest value in the above data is "-7.6" and is in column 3 which has the name "seventeen". Therefore "7.6", "seventeen" and its position value which in this case is 1 need to be written to the new text file. I then need a number of rows deleted from the above text file. E.G. the lowest value above is "-7.6" and is found at position "1" and is found in column 3 which as the name "seventeen". I therefore need seventeen rows deleted from the text file starting from and including position 1 so the the column in which the lowest value is found denotes the amount of rows that needs to be deleted and the position it is found at states the start point of the deletion

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  • Working around "one executable per project" in Visual C# for many small test programs

    - by Kevin Ivarsen
    When working with Visual Studio in general (or Visual C# Express in my particular case), it looks like each project can be configured to produce only one output - e.g. a single executable or a library. I'm working on a project that consists of a shared library and a few application, and I already have one project in my solution for each of those. However, during development I find it useful to write small example programs that can run one small subsystem in isolation (at a level that doesn't belong in the unit tests). Is there a good way to handle this in Visual Studio? I'd like to avoid adding several dozen separate projects to my solution for each small test program I write, especially when these programs will typically be less than 100 lines of code. I'm hoping to find something that lets me continue to work in Visual Studio and use its build system (rather than moving to something like NAnt). I could foresee the answer being something like: A way of setting this up in Visual Studio that I haven't found yet A GUI like NUnit's graphical runner that searches an assembly for classes with defined Main() functions that you can select and run A command line tool that lets you specify an assembly and a class with a Main function to run

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