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  • getting a "default" concrete class that implements an interface

    - by Roger Joys
    I am implementing a custom (and generic) Json.net serializer and hit a bump in the road that I could use some help on. When the deserializer is mapping to a property that is an interface, how can I best determine what sort of object to construct to deserialize to to place into the interface property. I have the following: [JsonConverter(typeof(MyCustomSerializer<foo>))] class foo { int Int1 { get; set; } IList<string> StringList {get; set; } } My serializer properly serializes this object, and but when it comes back in, and I try to map the json parts to to object, I have a JArray and an interface. I am currently instantiating anything enumerable like List as theList = Activator.CreateInstance(property.PropertyType); This works create to work with in the deserialization process, but when the property is IList, I get runtime complaints (obviously) about not being able to instantiate an interface. So how would I know what type of concrete class to create in a case like this? Thank you

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  • Javascript Getting Objects to Fallback to One Another

    - by Ian
    Here's a ugly bit of Javascript it would be nice to find a workaround. Javascript has no classes, and that is a good thing. But it implements fallback between objects in a rather ugly way. The foundational construct should be to have one object that, when a property fails to be found, it falls back to another object. So if we want a to fall back to b we would want to do something like: a = {sun:1}; b = {dock:2}; a.__fallback__ = b; then a.dock == 2; But, Javascript instead provides a new operator and prototypes. So we do the far less elegant: function A(sun) { this.sun = sun; }; A.prototype.dock = 2; a = new A(1); a.dock == 2; But aside from elegance, this is also strictly less powerful, because it means that anything created with A gets the same fallback object. What I would like to do is liberate Javascript from this artificial limitation and have the ability to give any individual object any other individual object as its fallback. That way I could keep the current behavior when it makes sense, but use object-level inheritance when that makes sense. My initial approach is to create a dummy constructor function: function setFallback(from_obj, to_obj) { from_obj.constructor = function () {}; from_obj.constructor.prototype = to_obj; } a = {sun:1}; b = {dock:2}; setFallback(a, b); But unfortunately: a.dock == undefined; Any ideas why this doesn't work, or any solutions for an implementation of setFallback? (I'm running on V8, via node.js, in case this is platform dependent)

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  • C# regular expression for finding forms with input tags in HTML?

    - by johnrl
    Hi all. I have a simple problem: I want to construct a regex that matches a form in HTML, but only if the form has any input tags. Example: The following should be matched (ignoring attributes): .. <form> .. <input/> .. </form> .. But the following should not (ignoring attributes): .. <form> .. </form> .. I have tried everything from look-arounds to capture groups but it quickly gets complicated. I want to believe there is a simple regex to capture the problem. Please note that it is important that the regex pairs the opening and closing tags according to the HTML code which means the following does not work: <form>.+<input/>.+</form> because it matches wrongly like this: .. <form> <--- This is wrongly matched as the opening tag .. </form> <form> <-- This is the correct opening tag of the correct form .. <input/> .. </form> <--- This is matched as the closing tag ..

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  • Java 8 Stream, getting head and tail

    - by lyomi
    Java 8 introduced a Stream class that resembles Scala's Stream, a powerful lazy construct using which it is possible to do something like this very concisely: def from(n: Int): Stream[Int] = n #:: from(n+1) def sieve(s: Stream[Int]): Stream[Int] = { s.head #:: sieve(s.tail filter (_ % s.head != 0)) } val primes = sieve(from(2)) primes takeWhile(_ < 1000) print // prints all primes less than 1000 I wondered if it is possible to do this in Java 8, so I wrote something like this: IntStream from(int n) { return IntStream.iterate(n, m -> m + 1); } IntStream sieve(IntStream s) { int head = s.findFirst().getAsInt(); return IntStream.concat(IntStream.of(head), sieve(s.skip(1).filter(n -> n % head != 0))); } IntStream primes = sieve(from(2)); PrimitiveIterator.OfInt it = primes.iterator(); for (int prime = it.nextInt(); prime < 1000; prime = it.nextInt()) { System.out.println(prime); } Fairly simple, but it produces java.lang.IllegalStateException: stream has already been operated upon or closed because both findFirst() and skip() is a terminal operation on Stream which can be done only once. I don't really have to use up the stream twice since all I need is the first number in the stream and the rest as another stream, i.e. equivalent of Scala's Stream.head and Stream.tail. Is there a method in Java 8 Stream that I can achieve this? Thanks.

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  • JavaScript Regex: Complicated input validation

    - by ScottSEA
    I'm trying to construct a regex to screen valid part and/or serial numbers in combination, with ranges. A valid part number is a two alpha, three digit pattern or /[A-z]{2}\d{3}/ i.e. aa123 or ZZ443 etc... A valid serial number is a five digit pattern, or /\d{5}/ 13245 or 31234 and so on. That part isn't the problem. I want combinations and ranges to be valid as well: 12345, ab123,ab234-ab245, 12346 - 12349 - the ultimate goal. Ranges and/or series of part and/or serial numbers in any combination. Note that spaces are optional when specifying a range or after a comma in a series. Note that a range of part numbers has the same two letter combination on both sides of the range (i.e. ab123 - ab239) I have been wrestling with this expression for two days now, and haven't come up with anything better than this: /^(?:[A-z]{2}\d{3}[, ]*)|(?:\d{5}[, ]*)|(?:([A-z]{2})\d{3} ?- ?\4\d{3}[, ]*)|(?:\d{5} ?- ?\d{5}[, ]*)$/ ... My Regex-Fu is weak.

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  • Building static (but complicated) lookup table using templates.

    - by MarkD
    I am currently in the process of optimizing a numerical analysis code. Within the code, there is a 200x150 element lookup table (currently a static std::vector < std::vector < double ) that is constructed at the beginning of every run. The construction of the lookup table is actually quite complex- the values in the lookup table are constructed using an iterative secant method on a complicated set of equations. Currently, for a simulation, the construction of the lookup table is 20% of the run time (run times are on the order of 25 second, lookup table construction takes 5 seconds). While 5-seconds might not seem to be a lot, when running our MC simulations, where we are running 50k+ simulations, it suddenly becomes a big chunk of time. Along with some other ideas, one thing that has been floated- can we construct this lookup table using templates at compile time? The table itself never changes. Hard-coding a large array isn't a maintainable solution (the equations that go into generating the table are constantly being tweaked), but it seems that if the table can be generated at compile time, it would give us the best of both worlds (easily maintainable, no overhead during runtime). So, I propose the following (much simplified) scenario. Lets say you wanted to generate a static array (use whatever container suits you best- 2D c array, vector of vectors, etc..) at compile time. You have a function defined- double f(int row, int col); where the return value is the entry in the table, row is the lookup table row, and col is the lookup table column. Is it possible to generate this static array at compile time using templates, and how?

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  • What is the best way to find a processed memory allocations in terms of C# objects

    - by Shantaram
    I have written various C# console based applications, some of them long running some not, which can over time have a large memory foot print. When looking at the windows perofrmance monitor via the task manager, the same question keeps cropping up in my mind; how do I get a break down of the number objects by type that are contributing to this footprint; and which of those are f-reachable and those which aren't and hence can be collected. On numerous occasions I've performed a code inspection to ensure that I am not unnecessarily holding on objects longer than required and disposing of objects with the using construct. I have also recently looked at employing the CG.Collect method when I have released a large number of objects (for example held in a collection which has just been cleared). However, I am not so sure that this made that much difference, so I threw that code away. I am guessing that there are tools in sysinternals suite than can help to resolve these memory type quiestions but I am not sure which and how to use them. The alternative would be to pay for a third party profiling tool such as JetBrains dotTrace; but I need to make sure that I've explored the free options first before going cap in hand to my manager.

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  • Constructor Overload Problem in C++ Inherrentance

    - by metdos
    Here my code snippet: class Request { public: Request(void); ……….. } Request::Request(void) { qDebug()<<"Request: "<<"Hello World"; } class LoginRequest :public Request { public: LoginRequest(void); LoginRequest(QDomDocument); …………… } LoginRequest::LoginRequest(void) { qDebug()<<"LoginRequest: "<<"Hello World"; requestType=LOGIN; requestId=-1; } LoginRequest::LoginRequest(QDomDocument doc){ qDebug()<<"LoginRequest: "<<"Hello World with QDomDocument"; LoginRequest::LoginRequest(); xmlDoc_=doc; } When call constructor of Overrided LoginRequest LoginRequest *test=new LoginRequest(doc); I came up with this result: Request: Hello World LoginRequest: Hello World with QDomDocument Request: Hello World LoginRequest: Hello World Obviously both constructor of LoginRequest called REquest constructor. Is there any way to cape with this situation? I can construct another function that does the job I want to do and have both constructors call that function. But I wonder is there any solution?

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  • Dealing with infinite loops when constructing states for LR(1) parsing

    - by Bruce
    I'm currently constructing LR(1) states from the following grammar. S->AS S->c A->aA A->b where A,S are nonterminals and a,b,c are terminals. This is the construction of I0 I0: S' -> .S, epsilon --------------- S -> .AS, epsilon S -> .c, epsilon --------------- S -> .AS, a S -> .c, c A -> .aA, a A -> .b, b And I1. From S, I1: S' -> S., epsilon //DONE And so on. But when I get to constructing I4... From a, I4: A -> a.A, a ----------- A -> .aA, a A -> .b, b The problem is A - .aA When I attempt to construct the next state from a, I'm going to once again get the exact same content of I4, and this continues infinitely. A similar loop occurs with S -> .AS So, what am I doing wrong? There has to be some detail that I'm missing, but I've browsed my notes and my book and either can't find or just don't understand what's wrong here. Any help?

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  • Request for advice about class design, inheritance/aggregation

    - by Lasse V. Karlsen
    I have started writing my own WebDAV server class in .NET, and the first class I'm starting with is a WebDAVListener class, modelled after how the HttpListener class works. Since I don't want to reimplement the core http protocol handling, I will use HttpListener for all its worth, and thus I have a question. What would the suggested way be to handle this: Implement all the methods and properties found inside HttpListener, just changing the class types where it matters (ie. the GetContext + EndGetContext methods would return a different class for WebDAV contexts), and storing and using a HttpListener object internally Construct WebDAVListener by passing it a HttpListener class to use? Create a wrapper for HttpListener with an interface, and constrct WebDAVListener by passing it an object implementing this interface? If going the route of passing a HttpListener (disguised or otherwise) to the WebDAVListener, would you expose the underlying listener object through a property, or would you expect the program that used the class to keep a reference to the underlying HttpListener? Also, in this case, would you expose some of the methods of HttpListener through the WebDAVListener, like Start and Stop, or would you again expect the program that used it to keep the HttpListener reference around for all those things? My initial reaction tells me that I want a combination. For one thing, I would like my WebDAVListener class to look like a complete implementation, hiding the fact that there is a HttpListener object beneath it. On the other hand, I would like to build unit-tests without actually spinning up a networked server, so some kind of mocking ability would be nice to have as well, which suggests I would like the interface-wrapper way. One way I could solve this would be this: public WebDAVListener() : WebDAVListener(new HttpListenerWrapper()) { } public WebDAVListener(IHttpListenerWrapper listener) { } And then I would implement all the methods of HttpListener (at least all those that makes sense) in my own class, by mostly just chaining the call to the underlying HttpListener object. What do you think? Final question: If I go the way of the interface, assuming the interface maps 1-to-1 onto the HttpListener class, and written just to add support for mocking, is such an interface called a wrapper or an adapter?

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  • jQuery: Moving window (or FIFO) type DIV?

    - by Legend
    I have been trying to get this effect for a couple of hours now and I must admit I am failing at it. I am trying to construct a DIV that accepts a particular number of items (say 5), when the 6th item is added, the first item that was aded should be removed (first-in-first-out). The feel should have some kind of a fadeIn and fadeOut. Here's what I managed to write till now: ... //Create a ul element with id 'ulele' and add it to a div ... //Do an ajax call and when an element arrives Hash = ComputeHash(message) if(!$("#" + Hash).exists()) { var element = $("<li></li>").html(message).attr('id', Hash).prependTo("#ulele"); $("#" + Hash).hide().delay(10000 - 1000 * messageNumber).show("slow"); _this.prune("#ulele"); } ... prune: function(divid) { $("#" + divid).children().each( function(i, elemLi) { if(i >= maxMessages) $(this).delay(10000).hide("slow").delay(10000).remove(); } ); } I've tried a couple of variations but the final effect I am getting is not that of a FIFO. The elements disappear instantaneously despite the delay and hide("slow") calls. Anyone has a more straightforward approach?

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  • Why is the main method not covered?

    - by Mike.Huang
    main method: public static void main(String[] args) throws Exception { if (args.length != EXPECTED_NUMBER_OF_ARGUMENTS) { System.err.println("Usage - java XFRCompiler ConfigXML PackageXML XFR"); } String configXML = args[0]; String packageXML = args[1]; String xfr = args[2]; AutoConfigCompiler compiler = new AutoConfigCompiler(); compiler.setConfigDocument(loadDocument(configXML)); compiler.setPackageInfoDoc(loadDocument(packageXML)); // compiler.setVisiblityDoc(loadDocument("VisibilityFilter.xml")); compiler.compileModel(xfr); } private static Document loadDocument(String fileName) throws Exception { TXDOMParser parser = (TXDOMParser) ParserFactory.makeParser(TXDOMParser.class.getName()); InputSource source = new InputSource(new FileInputStream(fileName)); parser.parse(source); return parser.getDocument(); } testcase: @Test public void testCompileModel() throws Exception { // construct parameters URL configFile = Thread.currentThread().getContextClassLoader().getResource("Ford_2008_Mustang_Config.xml"); URL packageFile = Thread.currentThread().getContextClassLoader().getResource("Ford_2008_Mustang_Package.xml"); File tmpFile = new File("Ford_2008_Mustang_tmp.xfr"); if(!tmpFile.exists()) { tmpFile.createNewFile(); } String[] args = new String[]{configFile.getPath(),packageFile.getPath(),tmpFile.getPath()}; try { // test main method XFRCompiler.main(args); } catch (Exception e) { assertTrue(true); } try { // test args length is less than 3 XFRCompiler.main(new String[]{"",""}); } catch (Exception e) { assertTrue(true); } tmpFile.delete(); } Coverage outputs displayed as the lines from String configXML = args[0]; in main method are not covered.

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  • How Best to Replace PL/SQL with C#?

    - by Mike
    Hi, I write a lot of one-off Oracle SQL queries/reports (in Toad), and sometimes they can get complex, involving lots of unions, joins, and subqueries, and/or requiring dynamic SQL, and/or procedural logic. PL/SQL is custom made for handling these situations, but as a language it does not compare to C#, and even if it did, it's tooling does not, and if even that did, forcing yet another language on the team is something to be avoided whenever possible. Experience has shown me that using SQL for the set based processing, coupled with C# for the procedural processing, is a powerful combination indeed, and far more readable, maintainable and enhanceable than PL/SQL. So, we end up with a number of small C# programs which typically would construct a SQL query string piece by piece and/or run several queries and process them as needed. This kind of code could easily be a disaster, but a good developer can make this work out quite well, and end up with very readable code. So, I don't think it's a bad way to code for smaller DB focused projects. My main question is, how best to create and package all these little C# programs that run ad hoc queries and reports against the database? Right now I create little report objects in a DLL, developed and tested with NUnit, but then I continue to use NUnit as the GUI to select and run them. NUnit just happens to provide a nice GUI for this kind of thing, even after testing has been completed. I'm also interested in suggestions for reporting apps generally. I feel like there is a missing piece or product. The perfect tool would allow writing and running C# inside of Toad, or SQL inside of Visual Studio, along with simple reporting facilities. All ideas will be appreciated, but let's make the assumption that PL/SQL is not the solution.

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  • Not getting key value from Identity column back after inserting new row with SubSonic ActiveRecord

    - by mikedevenney
    I'm sure I'm missing the obvious answer here, but could use a hand. I'm new to SubSonic and using version 3. I've got myself to the point of being able to query and insert, but I'm stuck with how I would get the value of the identity column back after my insert. I saw another post that mentioned Linq Templates. I'm not using those (at least I don't think I am...?) TIA ... UPDATE ... So I've been debugging through my code watching how the SubSonic code works and I found where the indentity column is being ignored. I use int as the datatype for my ID columns in the database and set them as identity. Since int is a non-nullable data type in c# the logical test in the Add method (public void Add(IDataProvider provider)) that checks if there is a value in the key column by doing a (key==null) could be the issue. The code that gets the new value for the identity field is in the 'true path', since an int can't be null and I use ints as my identity column data types this test will never pass. The ID field for my object has a 0 in it that I didn't put there. I assume it's set during the initialization of the object. Am I off base here? Is the answer to change my data types in the database? Another question (more a curiosity). I noticed that some of the properties in the generated classes are declared with a ? after the datatype. I'm not familiar with this declaration construct... what gives? There are some declared as an int (non key fields) and others that are declared as int? (key fields). Does this have something to do with how they're treated at initialization? Any help is appreciated! --BUMP--

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  • Simple wxPython Frame Contents Resizing - Ratio?

    - by Wes
    I have a wxPython app with one frame and one panel. On that panel are a number of static boxes, each of which has buttons and textboxes. I have just begun reading about sizers, but they seem like they might be more than what I need, or it could that they are exactly what I need but I don't know how to use them correctly! The frame currently opens at 1920 x 1080. If the user drags the bottom right corner to resize the app, I just want everything to get smaller or larger as needed to keep the same size ratio. Is this possible? Thank you! edit: additional info: I used wxPython 2.8 and Boa to construct the GUI. I am contemplating trying another gui ide. So after reading some more about sizers, I am thinking about doing the following: add a gridsizer and basically divide my window's elements into rows and columns, then set each row and column's size as necessary until I achieve the original layout. Then I guess set the rows and columns to resize correctly? Is this a decent idea?

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  • RequestBuilder timeouts and browser connection limits per domain.

    - by WesleyJohnson
    This is specifically about GWT's RequestBuilder, but should apply to general XHR as well. My company is having me build a near realtime chat application over HTTP. Yes, I do realize there are better ways to do chat aplications, but this is what they want. Eventually we want it working on the iPad/iPhone as well so flash is out, which rules out websockets and comet as well, I think? Anyway, I'm running into issues were I've set GWT's RequestBuilder timeout to 10 seconds and we get very random and sporadic timeouts. We've got error handling and emailing on the server side and never get any errors, which suggests the underlying XHR request that RequestBuilder is built on, never gets to the server and times out after 10 seconds. We're using these request to poll the server for new messages rather often and also for sending new messages to the server and also polling (less frequently) for other parts of application. What I'm afraid of is that we're running into the browsers limit on concurrent connections to the same domain (2 for IE by default?). Now my question is - If I construct a RequestBuilder and call it's send() method and the browser blocks it from sending until one of the 2 connections per domain is free, does the timeout still start while the request is being blocked or will it not start until the browser actually releases the underlying XHR? I hope that's clear, if not please let me know and I'll try to explain more.

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  • C++ Templates: Convincing self against code bloat

    - by ArunSaha
    I have heard about code bloats in context of C++ templates. I know that is not the case with modern C++ compilers. But, I want to construct an example and convince myself. Lets say we have a class template< typename T, size_t N > class Array { public: T * data(); private: T elems_[ N }; }; template< typename T, size_t N > T * Array<T>::data() { return elems_; } Further, let's say types.h contains typedef Array< int, 100 > MyArray; x.cpp contains MyArray ArrayX; and y.cpp contains MyArray ArrayY; Now, how can I verify that the code space for MyArray::data() is same for both ArrayX and ArrayY? What else I should know and verify from this (or other similar simple) examples? If there is any g++ specific tips, I am interested for that too. PS: Regarding bloat, I am concerned even for the slightest of bloats, since I come from embedded context.

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  • optimize output value using a class and public member

    - by wiso
    Suppose you have a function, and you call it a lot of times, every time the function return a big object. I've optimized the problem using a functor that return void, and store the returning value in a public member: #include <vector> const int N = 100; std::vector<double> fun(const std::vector<double> & v, const int n) { std::vector<double> output = v; output[n] *= output[n]; return output; } class F { public: F() : output(N) {}; std::vector<double> output; void operator()(const std::vector<double> & v, const int n) { output = v; output[n] *= n; } }; int main() { std::vector<double> start(N,10.); std::vector<double> end(N); double a; // first solution for (unsigned long int i = 0; i != 10000000; ++i) a = fun(start, 2)[3]; // second solution F f; for (unsigned long int i = 0; i != 10000000; ++i) { f(start, 2); a = f.output[3]; } } Yes, I can use inline or optimize in an other way this problem, but here I want to stress on this problem: with the functor I declare and construct the output variable output only one time, using the function I do that every time it is called. The second solution is two time faster than the first with g++ -O1 or g++ -O2. What do you think about it, is it an ugly optimization?

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  • Querying the size of a drive on a remote server is giving me an error

    - by Testifier
    Here's what I have: public static bool DriveHasLessThanTenPercentFreeSpace(string server) { long driveSize = 0; long freeSpace = 0; var oConn = new ConnectionOptions {Username = "username", Password = Settings.Default.SQLServerAdminPassword}; var scope = new ManagementScope("\\\\" + server + "\\root\\CIMV2", oConn); //connect to the scope scope.Connect(); //construct the query var query = new ObjectQuery("SELECT FreeSpace FROM Win32_LogicalDisk where DeviceID = 'D:'"); //this class retrieves the collection of objects returned by the query var searcher = new ManagementObjectSearcher(scope, query); //this is similar to using a data adapter to fill a data set - use an instance of the ManagementObjectSearcher to get the collection from the query and store it ManagementObjectCollection queryCollection = searcher.Get(); //iterate through the object collection and get what you're looking for - in my case I want the FreeSpace of the D drive foreach (ManagementObject m in queryCollection) { //the FreeSpace value is in bytes freeSpace = Convert.ToInt64(m["FreeSpace"]); //error happens here! driveSize = Convert.ToInt64(m["Size"]); } long percentFree = ((freeSpace / driveSize) * 100); if (percentFree < 10) { return true; } return false; } This line of code is giving me an error: driveSize = Convert.ToInt64(m["Size"]); The error says: ManagementException was unhandled by user code Not found I'm assuming the query to get the drive size is wrong. Please note that I AM getting the freeSpace value at the line: freeSpace = Convert.ToInt64(m["FreeSpace"]); So I know the query IS working for freeSpace. Can anyone give me a hand?

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  • PHP loop hanging/interspersed/threaded through HTML

    - by sandyv
    I can't figure out how to say what I'm talking about which is a big part of why I'm stuck. In PHP I often see code like this html <?php language construct that uses brackets { some code; ?> more html <?php some more code; } ?> rest of html Is there any name for this? Having seen this lead me to try it out so here is a concrete example whose behavior doesn't make sense to me <div id="content"> <ul id="nav"> <?php $path = 'content'; $dir = dir($path); while(false !== ($file = $dir->read())) { if(preg_match('/.+\.txt/i', $file)) { echo "<li>$file</li>"; ?> </ul> <?php echo file_get_contents($path . '/' . $file); } } ?> </div> Which outputs roughly <div><ul><li></li></ul><li></li>...</div> instead of <div><ul><li></li>...</ul></div> which is what I thought would happen and what I want to happen.

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  • How to Populate a 'Tree' structure 'Declaratively'

    - by mackenir
    I want to define a 'node' class/struct and then declare a tree of these nodes in code in such a way that the way the code is formatted reflects the tree structure, and there's not 'too much' boiler plate in the way. Note that this isn't a question about data structures, but rather about what features of C++ I could use to arrive at a similar style of declarative code to the example below. Possibly with C++0X this would be easier as it has more capabilities in the area of constructing objects and collections, but I'm using Visual Studio 2008. Example tree node type: struct node { string name; node* children; node(const char* name, node* children); node(const char* name); }; What I want to do: Declare a tree so its structure is reflected in the source code node root = node("foo", [ node("child1"), node("child2", [ node("grand_child1"), node("grand_child2"), node("grand_child3" ]), node("child3") ]); NB: what I don't want to do: Declare a whole bunch of temporary objects/colls and construct the tree 'backwards' node grandkids[] = node[3] { node("grand_child1"), node("grand_child2"), node("grand_child3" }; node kids[] = node[3] { node("child1"), node("child2", grandkids) node("child3") }; node root = node("foo", kids);

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  • Help! I'm a Haskell Newbie

    - by Darknight
    I've only just dipped my toe in the world of Haskell as part of my journey of programming enlightenment (moving on from, procedural to OOP to concurrent to now functional). I've been trying an online Haskell Evaluator. However I'm now stuck on a problem: Create a simple function that gives the total sum of an array of numbers. In a procedural language this for me is easy enough (using recursion) (c#) : private int sum(ArrayList x, int i) { if (!(x.Count < i + 1)) { int t = 0; t = x.Item(i); t = sum(x, i + 1) + t; return t; } } All very fine however my failed attempt at Haskell was thus: let sum x = x+sum in map sum [1..10] this resulted in the following error (from that above mentioned website): Occurs check: cannot construct the infinite type: a = a -> t Please bear in mind I've only used Haskell for the last 30 minutes! I'm not looking simply for an answer but a more explanation of it. Thanks in advanced.

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  • servicestack Razor view with request and response DTO

    - by user7398
    I'm having a go with the razor functionality in service stack. I have a razor cshtml view working for one of my response DTO's. I need to access some values from the request DTO in the razor view that have been filled in from some fields from the REST route, so i can construct a url to put into the response html page and also label some form labels. Is there anyway of doing this? I don't want to duplicate the property from the request DTO into the response DTO just for this html view. Because i'm trying to emulate an existing REST service of another product, i do not want to emit extra data just for the html view. eg http://localhost/rest/{Name}/details/{Id} eg @inherits ViewPage<DetailsResponse> @{ ViewBag.Title = "todo title"; Layout = "HtmlReport"; } this needs to come from the request dto NOT @Model <a href="/rest/@Model.Name">link to user</a> <a href="/rest/@Model.Name/details/@Model.Id">link to user details</a>

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  • parsing of mathematical expressions

    - by gcc
    (in c90) (linux) input: sqrt(2 - sin(3*A/B)^2.5) + 0.5*(C*~(D) + 3.11 +B) a b /*there are values for a,b,c,d */ c d input: cos(2 - asin(3*A/B)^2.5) +cos(0.5*(C*~(D)) + 3.11 +B) a b /*there are values for a,b,c,d */ c d input: sqrt(2 - sin(3*A/B)^2.5)/(0.5*(C*~(D)) + sin(3.11) +ln(B)) /*max lenght of formula is 250 characters*/ a b /*there are values for a,b,c,d */ c /*each variable with set of floating numbers*/ d As you can see infix formula in the input depends on user. My program will take a formula and n-tuples value. Then it calculate the results for each value of a,b,c and d. If you wonder I am saying ;outcome of program is graph. /sometimes,I think i will take input and store in string. then another idea is arise " I should store formula in the struct" but i don't know how I can construct the code on the base of structure./ really, I don't know way how to store the formula in program code so that I can do my job. can you show me? /* a,b,c,d is letters cos,sin,sqrt,ln is function*/

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  • How Best to Replace Ugly Queries and Dynamic PL/SQL with C#?

    - by Mike
    Hi, I write a lot of one-off Oracle SQL queries (in Toad), and sometimes they can get complex, involving lots of unions, joins, and subqueries, and sometimes requiring dynamic SQL. That is, sometimes SQL queries require set based processing along with significant procedural processing. This is what PL/SQL is custom made for, but as a language it does not begin to compare to C#. Now and then I convert a PL/SQL procedure to C#, and am always amazed at how much cleaner and easier to both read and write the C# version is. The C# program might for example construct a SQL query string piece by piece and/or run several queries and process them as needed. The C# version is usually much faster as well, which must mean that I'm not very good at PL/SQL either. I do not currently have access to LINQ. My question is, how best to package all these little C# programs, which are really just mini reports, that is, replacements for ugly SQL queries? Right now I'm actually using NUnit to hold them, and calling each report a [Test], even though they aren't really tests. NUnit just happens to provide a convenient packaging framework.

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