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  • Post JSON array to mvc controller

    - by Yustme
    I'm trying to post a JSON array to a mvc controller. But no matter what i try, everything is 0 or null. I have this table that contains textboxes. I need from all those textboxes it's ID and value as an object. This is my java code: $(document).ready(function () { $('#submitTest').click(function (e) { var $form = $('form'); var trans = new Array(); var parameters = { TransIDs: $("#TransID").val(), ItemIDs: $("#ItemID").val(), TypeIDs: $("#TypeID").val(), }; trans.push(parameters); if ($form.valid()) { $.ajax( { url: $form.attr('action'), type: $form.attr('method'), data: JSON.stringify(parameters), dataType: "json", contentType: "application/json; charset=utf-8", success: function (result) { $('#result').text(result.redirectTo) if (result.Success == true) { return fase; } else { $('#Error').html(result.Html); } }, error: function (request) { alert(request.statusText) } }); } e.preventDefault(); return false; }); }); This is my view code: <table> <tr> <th>trans</th> <th>Item</th> <th>Type</th> </tr> @foreach (var t in Model.Types.ToList()) { { <tr> <td> <input type="hidden" value="@t.TransID" id="TransID" /> <input type="hidden" value="@t.ItemID" id="ItemID" /> <input type="hidden" value="@t.TypeID" id="TypeID" /> </td> </tr> } } </table> This is the controller im trying to receive the data to: [HttpPost] public ActionResult Update(CustomTypeModel ctm) { return RedirectToAction("Index"); } What am i doing wrong?

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  • Using an embedded DB (SQLite / SQL Compact) for Message Passing within an app?

    - by wk1989
    Hello, Just out of curiosity, for applications that have a fairly complicated module tree, would something like sqlite/sql compact edition work well for message passing? So if I have modules containing data such as: \SubsystemA\SubSubSysB\ModuleB\ModuleDataC, \SubSystemB\SubSubSystemC\ModuleA\ModuleDataX Using traditional message passing/routing, you have to go through intermediate modules in order to pass a message to ModuleB to request say ModuleDataC. Instead of doing that, if we we simply store "\SubsystemA\SubSubSysB\ModuleB\ModuleDataC" in a sqlite database, getting that data is as simple as a sql query and needs no routing and passing stuff around. Has anyone done this before? Even if you haven't, do you foresee any issues & performance impact? The only concern I have right now would be the passing of custom types, e.g. if ModuleDataC is a custom data structure or a pointer, I'll need some way of storing the data structure into the DB or storing the pointer into the DB. Thanks, JW EDIT One usage case I haven't thought about is when you want to send a message from ModuleA to ModuleB to get ModuleB to do something rather than just getting/setting data. Is it possible to do this using an embedded DB? I believe callback from the DB would be needed, how feasible is this?

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  • Javascript Regex: Testing string for intelligent query

    - by Shyam
    Hi, I have a string that holds user input. This string can contain various types of data, like: a six digit id a zipcode that contains out of 4 digits and two alphanumeric characters a name (characters only) As I am using this string to search through a database, the query type is determined on the type of search, which i want to handle serverside using JavaScript (yes, I am using JavaScript serverside). Searching on StackOverflow, brought me some interesting information, like the .test-method, which seems perfect for my needs. The test-method returns either true or false based on the evaluation on the string using a regex object. I am using this page as a reference: http://www.javascriptkit.com/jsref/regexp.shtml So I am trying to determine the zipcode, by using the following very noobish regex. var r = /[A-Za-z]{2,2}/ As far I can understand, this should limit the amount of occurrences of alphanumeric characters to a maximum of two. See beneath the output of my JavaScript console. > var r = /[A-Za-z]{2,2}/ > var x = "2233AL" > r.test(x) true > var x = "2233A" > r.test(x) false > var x = "2233ALL" > r.test(x) true /* i want this to be false */ > A little help would be really appreciated!

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  • Web services or shared database for (game) server communication?

    - by jaaronfarr
    We have 2 server clusters: the first is made up of typical web applications backed by SQL databases. The second are highly optimized multiplayer game servers which keep all data in memory. Both clusters communicate with clients via HTTP (Ajax with JSON). There are a few cases in which we need to share data between the two server types, for example, reporting back and storing the results of a game (should ultimately end up in the database). We're considering several approaches for inter-server communication: Just share the MySQL databases between clusters (introduce SQL to the game servers) Sharing data in a distributed key-value store like Memcache, Redis, etc. Use an RPC technology like Google ProtoBufs or Apache Thrift Using RESTful web services (the game server would POST back to the web servers, for example) At the moment, we're leaning towards web services or just sharing the database. Sharing the database seems easy, but we're concerned this adds extra memory and a new dependency into the game servers. Web services provide good separation of concerns and fit with the existing Ajax we use, but add complexity, overhead and many more ways for communication to fail. Are there any other good reasons not to use one or the other approach? Which would be easier to scale?

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  • C# specifying generic delegate type param at runtime

    - by smerlin
    following setup, i have several generic functions, and i need to choose the type and the function identified by two strings at runtime. my first try looked like this: public static class FOOBAR { public delegate void MyDelegateType(int param); public static void foo<T>(int param){...} public static void bar<T>(int param){...} public static void someMethod(string methodstr, string typestr) { MyDelegateType mydel; Type mytype; switch(typestr) { case "int": mytype = typeof(int); break; case "double": mytype = typeof(double); break; default: throw new InvalidTypeException(typestr); } switch(methodstr) { case "foo": mydel = foo<mytype>; //error break; case "bar": mydel = bar<mytype>; //error break; default: throw new InvalidTypeException(methodstr); } for(int i=0; i<1000; ++i) mydel(i); } } since this didnt work, i nested those switchs (a methodstr switch inside the typestr switch or viceversa), but that solution is really ugly and unmaintainable. The number of types is pretty much fixed, but the number of functions like foo or bar will increase by high numbers, so i dont want nested switchs. So how can i make this working without using nested switchs ?

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  • Why does mmap() fail with ENOMEM on a 1TB sparse file?

    - by metadaddy
    I've been working with large sparse files on openSUSE 11.2 x86_64. When I try to mmap() a 1TB sparse file, it fails with ENOMEM. I would have thought that the 64 bit address space would be adequate to map in a terabyte, but it seems not. Experimenting further, a 1GB file works fine, but a 2GB file (and anything bigger) fails. I'm guessing there might be a setting somewhere to tweak, but an extensive search turns up nothing. Here's some sample code that shows the problem - any clues? #include <errno.h> #include <fcntl.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/mman.h> #include <sys/types.h> #include <unistd.h> int main(int argc, char *argv[]) { char * filename = argv[1]; int fd; off_t size = 1UL << 40; // 30 == 1GB, 40 == 1TB fd = open(filename, O_RDWR | O_CREAT | O_TRUNC, 0666); ftruncate(fd, size); printf("Created %ld byte sparse file\n", size); char * buffer = (char *)mmap(NULL, (size_t)size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); if ( buffer == MAP_FAILED ) { perror("mmap"); exit(1); } printf("Done mmap - returned 0x0%lx\n", (unsigned long)buffer); strcpy( buffer, "cafebabe" ); printf("Wrote to start\n"); strcpy( buffer + (size - 9), "deadbeef" ); printf("Wrote to end\n"); if ( munmap(buffer, (size_t)size) < 0 ) { perror("munmap"); exit(1); } close(fd); return 0; }

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  • can I use NSDictionary values as [@"[array abjectAtIndex:value]", key1,nil] ?

    - by srikanth rongali
    I have a string of comma separated values in this way (0.2,0.3,0.4,1.0). I used componentsSeperatedByString to store the values in an NSArray. Now I need to store them in NSDictionary as (1st value from NSArray), key1, (2nd Value of NsArray), key2,..nil]; My program is in this way NSArray *split1; NSDictionary *enemy1; float value1; for(id line in lines) { string1 = line; split1 = [string1 componentsSeparatedByString:@","]; numberOfValues = [split1 count]; for(id value in split1) { enemy1 = [NSDictionary dictionaryWithObjectsAndKeys:@"[[split1 objectAtIndex:0]flaotValue]", @"A1", nil]; } } value1 = [enemy1 objectForKey:@"A1"]; Here lines is an NSArray consisting of CSV strings of number 10. I am getting error as error: incompatible types in assignment Should I do not write my code in this way? Where I doing wrong ? Please tell me my mistakes. Thank You.

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  • C vs C++ function questions

    - by james
    I am learning C, and after starting out learning C++ as my first compiled language, I decided to "go back to basics" and learn C. There are two questions that I have concerning the ways each language deals with functions. Firstly, why does C "not care" about the scope that functions are defined in, whereas C++ does? For example, int main() { donothing(); return 0; } void donothing() { } the above will not compile in a C++ compiler, whereas it will compile in a C compiler. Why is this? Isn't C++ mostly just an extension on C, and should be mostly "backward compatible"? Secondly, the book that I found (Link to pdf) does not seem to state a return type for the main function. I check around and found other books and websites and these also commonly do not specify return types for the main function. If I try to compile a program that does not specify a return type for main, it compiles fine (although with some warnings) in a C compiler, but it doesn't compile in a C++ compiler. Again, why is that? Is it better style to always specify the return type as an integer rather than leaving it out? Thanks for any help, and just as a side note, if anyone can suggest a better book that I should buy that would be great!

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  • Manual Linq to SQL entity framework mapping

    - by kprobst
    I've been playing with the O/R designer in VS and I was wondering if someone could shed come light on this. I'm used to OR mappers that are largely manual (homegrown and e.g., NHibernate). I don't mind encoding the entity classes myself, since they don't change all that often to begin with, and I have this irrational fear of designers and auto generated code as it is. I have noticed that the generated entity classes contain a lot of boilerplate extensibility methods, e.g. On[Property]Changed() and so on where [Property] is a mapped member of the class. These are placed in the setters of the property accessors. I assume it's OK if I don't include these when I do my hand coding, correct? They would be nice if I needed some sort of interception pattern but that's certainly not the case. I guess I just need to know if any of those methods are required by the entity framework to keep track of changes to the mapping types in order for things to work when updating the database. Thanks!

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  • How to format JSON Date?

    - by Mark Struzinski
    I'm taking my first crack at AJAX with jQuery. I'm getting my data onto my page, but I'm having some trouble with the JSON that is returned for Date data types. Basically, I'm getting a string back that looks like this: /Date(1224043200000)/ From a total newbie at JSON - How do I format this to a short date format? Should this be handled somewhere in the jQuery code? I've tried the jQuery.UI.datepicker plugin using $.datepicker.formatDate() wiuth no success. FYI: Here's the solution I came up with using a combination of the answers here: function getMismatch(id) { $.getJSON("Main.aspx?Callback=GetMismatch", { MismatchId: id }, function(result) { $("#AuthMerchId").text(result.AuthorizationMerchantId); $("#SttlMerchId").text(result.SettlementMerchantId); $("#CreateDate").text(formatJSONDate(Date(result.AppendDts))); $("#ExpireDate").text(formatJSONDate(Date(result.ExpiresDts))); $("#LastUpdate").text(formatJSONDate(Date(result.LastUpdateDts))); $("#LastUpdatedBy").text(result.LastUpdateNt); $("#ProcessIn").text(result.ProcessIn); } ); return false; } function formatJSONDate(jsonDate){ var newDate = dateFormat(jsonDate, "mm/dd/yyyy"); return newDate; } This solution got my object from the callback method and displayed the dates on the page properly using the date format library.

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  • Ruby on Rails: custom instance creation failing at redirect

    - by Jack
    I am at an absolute loss as to what I am doing wrong with the following code. I am trying to implement a messaging system within my application, but want it to be handle different types of messages. In this case, I want to create a "request" message of ':message_type = 1'. Instead of using forms as I usually have, I want to make this instance the moment the link is clicked. Here is how I have it set up in the show erb file for "user": <%=link_to "Send friend request", :action=>"request", :controller => "messages", :id => @user.id %> and in the controller: def request @message = Message.new(:sender_id => current_user.id,:user_id => params[:id],:message_type => 1) if @message.save flash[:notice] = 'Message was successfully created.' redirect_to message_path(@message) else redirect_to message_path(@message) end end This results in the following error message: undefined method `rewrite' for nil:NilClass with the trace looking like c:/ruby/lib/ruby/gems/1.8/gems/activesupport-2.3.5/lib/active_support/whiny_nil.rb:52:in `method_missing' c:/ruby/lib/ruby/gems/1.8/gems/actionpack-2.3.5/lib/action_controller/base.rb:634:in `url_for' (eval):16:in `message_path' app/controllers/messages_controller.rb:11:in `request' I have used map.resources :messages in the routes.rb file, and done the appropriate :has_many and :belongs_to associations in the models of user and message.

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  • Interesting Scala typing solution, doesn't work in 2.7.7?

    - by djc
    I'm trying to build some image algebra code that can work with images (basically a linear pixel buffer + dimensions) that have different types for the pixel. To get this to work, I've defined a parametrized Pixel trait with a few methods that should be able to get used with any Pixel subclass. (For now, I'm only interested in operations that work on the same Pixel type.) Here it is: trait Pixel[T <: Pixel[T]] { def mul(v: Double): T def max(v: T): T def div(v: Double): T def div(v: T): T } Now I define a single Pixel type that has storage based on three doubles (basically RGB 0.0-1.0), I've called it TripleDoublePixel: class TripleDoublePixel(v: Array[Double]) extends Pixel[TripleDoublePixel] { var data: Array[Double] = v def this() = this(Array(0.0, 0.0, 0.0)) def toString(): String = { "(" + data(0) + ", " + data(1) + ", " + data(2) + ")" } def increment(v: TripleDoublePixel) { data(0) += v.data(0) data(1) += v.data(1) data(2) += v.data(2) } def mul(v: Double): TripleDoublePixel = { new TripleDoublePixel(data.map(x => x * v)) } def div(v: Double): TripleDoublePixel = { new TripleDoublePixel(data.map(x => x / v)) } def div(v: TripleDoublePixel): TripleDoublePixel = { var tmp = new Array[Double](3) tmp(0) = data(0) / v.data(0) tmp(1) = data(1) / v.data(1) tmp(2) = data(2) / v.data(2) new TripleDoublePixel(tmp) } def max(v: TripleDoublePixel): TripleDoublePixel = { val lv = data(0) * data(0) + data(1) * data(1) + data(2) * data(2) val vv = v.data(0) * v.data(0) + v.data(1) * v.data(1) + v.data(2) * v.data(2) if (lv > vv) (this) else v } } Now I want to write code to use this, that doesn't have to know what type the pixels are. For example: def idiv[T](a: Image[T], b: Image[T]) { for (i <- 0 until a.data.size) { a.data(i) = a.data(i).div(b.data(i)) } } Unfortunately, this doesn't compile: (fragment of lindet-gen.scala):145: error: value div is not a member of T a.data(i) = a.data(i).div(b.data(i)) I was told in #scala that this worked for someone else, but that was on 2.8. I've tried to get 2.8-rc1 going, but it doesn't compile for me. Is there any way to get this to work in 2.7.7?

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  • Cocoa Drag and Drop, reading back the data. [Newbie]

    - by kodai
    Ok, I have a NSOutlineView set up, and I want it to capture PDF's if a pdf is dragged into the NSOutlineView. My first question, I have the following code: [outlineView registerForDraggedTypes:[NSArray arrayWithObjects:NSStringPboardType, NSFilenamesPboardType, nil]]; In all the apple Docs and examples I've seen I've also seen something like MySupportedType being an object registered for dragging. What does this mean? Do I change the code to be: [outlineView registerForDraggedTypes:[NSArray arrayWithObjects:@"pdf", NSStringPboardType, NSFilenamesPboardType, nil]]; Currently I have it set up to recognize drag and drop, and I can even make it spit out the URL of the dragged file once the drag is accepted, however, this leads me to my second question. I want to keep a copy of those PDF's app side. I suppose, and correct me if I'm wrong, that the best way to do this is to grab the data off the clipboard, save it in some persistant store, and that's that. (as apposed to using some sort of copy command and literally copying the file to the app director.) That being said, I'm not sure how to do that. I've the code: - (BOOL)outlineView:(NSOutlineView *)ov acceptDrop:(id <NSDraggingInfo>)info item:(id)item childIndex:(NSInteger)childIndex { NSPasteboard *pboard = [info draggingPasteboard]; NSURL *fileURL; if ( [[pboard types] containsObject:NSURLPboardType] ) { fileURL = [NSURL URLFromPasteboard:pboard]; // Perform operation using the file’s URL } NSData *data = [pboard dataForType:@"NSPasteboardTypePDF"]; But this never actually gets any data. Like I said before, it does get the URL, just not the data. Does anyone have any advise on how to get this going? Thanks so much!

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  • Conditionally colour data points outside of confidence bands in R

    - by D W
    I need to colour datapoints that are outside of the the confidence bands on the plot below differently from those within the bands. Should I add a separate column to my dataset to record whether the data points are within the confidence bands? Can you provide an example please? Example dataset: ## Dataset from http://www.apsnet.org/education/advancedplantpath/topics/RModules/doc1/04_Linear_regression.html ## Disease severity as a function of temperature # Response variable, disease severity diseasesev<-c(1.9,3.1,3.3,4.8,5.3,6.1,6.4,7.6,9.8,12.4) # Predictor variable, (Centigrade) temperature<-c(2,1,5,5,20,20,23,10,30,25) ## For convenience, the data may be formatted into a dataframe severity <- as.data.frame(cbind(diseasesev,temperature)) ## Fit a linear model for the data and summarize the output from function lm() severity.lm <- lm(diseasesev~temperature,data=severity) jpeg('~/Desktop/test1.jpg') # Take a look at the data plot( diseasesev~temperature, data=severity, xlab="Temperature", ylab="% Disease Severity", pch=16, pty="s", xlim=c(0,30), ylim=c(0,30) ) title(main="Graph of % Disease Severity vs Temperature") par(new=TRUE) # don't start a new plot ## Get datapoints predicted by best fit line and confidence bands ## at every 0.01 interval xRange=data.frame(temperature=seq(min(temperature),max(temperature),0.01)) pred4plot <- predict( lm(diseasesev~temperature), xRange, level=0.95, interval="confidence" ) ## Plot lines derrived from best fit line and confidence band datapoints matplot( xRange, pred4plot, lty=c(1,2,2), #vector of line types and widths type="l", #type of plot for each column of y xlim=c(0,30), ylim=c(0,30), xlab="", ylab="" )

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  • How to iterate & retrieve values from NSArray of NSArrays of NSDictionaries

    - by chinjazz
    I'm stumpped on how iterate and get values for an Array of Arrays of NSDictionaries (different classes/entities). Here's what I'm currently doing: 1) Constructing two separate arrays of NSDictionaries (different entities) 2) Combining both arrays with: NSMutableArray *combinedArrayofDicts = [[NSMutableArray alloc] initWithObjects: sizesArrayOfDicts, wishListArrayOfDicts , nil]; 3) Then archive combinedArrayofDicts : NSData *dataToSend = [NSKeyedArchiver archivedDataWithRootObject:combinedArrayofDicts]; 4) Transmit over GameKit [self.session sendDataToAllPiers:dataToSend withDataMode: GKSendDataReliable error:nil]; 5) How would I manage traversing thru this array on the receiving end? I want to fetch values by for each class which is key'ed by classname: Here's how it looks via NSLog (2 Sizes Dicts, and 1 Wishlist Dict) Printing description of receivedArray: <__NSArrayM 0xbc65eb0>( <__NSArrayM 0xbc651f0>( { classname = Sizes; displayOrder = 0; share = 1; sizeType = Neck; value = "13\" or 33 (cm)"; }, { classname = Sizes; displayOrder = 0; share = 1; sizeType = Sleeve; value = "34\" or 86 (cm)"; } ) , <__NSArrayM 0xbc65e80>( { classname = Wishlist; detail = ""; displayOrder = 0; imageString = ""; latitude = "30.33216666666667"; link = "http://maps.google.com/maps?q=loc:30.332,-81.41"; longitude = "-81.40949999999999"; name = bass; share = 1; store = ""; } ) ) (lldb) In my for loop I'm issuing this: NSString *value = [dict objectForKey:@"classname"]; and get an exception: * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSArrayM objectForKey:]: unrecognized selector sent to instance 0xbc651f0' Is this frowned upon as far as mixing object types in arrays of arrays?

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  • j_security_check to SSO in different module under Oracle App Server?

    - by thebearinboulder
    I have an existing j2ee application running on Oracle App Server. It is targeted towards paying customers so the content is secured and a SSO module properly intercepts all requests for secured content. Now the company is adding a unbranded public-facing module with a number of unsecured pages. At one point the user is expected to register for a free account and log in to proceed further. Think doctors adding a public-facing site with information for potential patients, or lawyers adding a public-facing site with information for potential clients. There's some information on the session and the usual approach would be to authenticate the user, persist the session information using the now-known user id, invalidate the existing session (to prevent certain types of attacks), the reload the session information before returning to the user. I can't just persist it under the session id since that's about to change. The glitch is that the existing application already has an SSO module and I get a 404 error every time I try to direct to j_security_check. I've tried that, /sso/j_security_check, even http://localhost/sso/j_security_check, all without success. I noticed that an earlier question said that tomcat requires access to a secured page before j_security_check is even visible. I don't know if that's the case with Oracle AS. Ideas? Or is the best approach to continue arguing that we have a different user base so it would be better to handle authentication in our own module anyway?

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  • Create Extension Method to Produce Open & Closing Tags like Html.BeginForm()

    - by DaveDev
    Hi Guys I wonder if it's possible to create an extension method which has functionality & behaviour similar to Html.BeginForm(), in that it would generate a complete Html tag, and I could specificy its contents inside <% { & } %> tags. For example, I could have a view like: <% using(Html.BeginDiv("divId")) %> <% { %> <!-- Form content goes here --> <% } %> This capability would be very useful in the context of the functionality I'm trying to produce with the example in this question This would give me the ability to create containers for the types that I'll be <% var myType = new MyType(123, 234); %> <% var tag = new TagBuilder("div"); %> <% using(Html.BeginDiv<MyType>(myType, tag) %> <% { %> <!-- controls used for the configuration of MyType --> <!-- represented in the context of a HTML element, e.g.: --> <div class="MyType" prop1="123" prop2="234"> <!-- add a select here --> <!-- add a radio control here --> <!-- whatever, it represents elements in the context of their type --> </div> <% } %> I realise this will produce invalid XHTML, but I think there could be other benefits that outweigh this, especially since this project doesn't require that the XHTML validate to the W3C standards. Thanks Dave

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  • Const Discards Qualifers: C++

    - by user991673
    I'm using OpenGL to render camera perspectives, and a one point in my code I'm trying to take the direction of the light (shown here as type "Vector4") and multiply it by a matrix of type "Matrix4x4" that represents the Modelview transformation (sorry if this is not making any sense, this is for a school project, as such I'm still learning about this stuff) Anyway, my code goes as follows... Vector4 lightDirection = data->dir * follow->getModelviewMatrix().getInverse().getTranspose(); data->dir = lightDirection; setLight(*data); this give me the following error: passing 'const vec4<double>' as 'this' argument of 'vec4<T>& vec4<T>::operator=(const vec4<T>&)[with T = double]' discards qualifiers Again, much of this code is prewritten for the class (namely the vector and matrix types) but if someone could just help me decipher what the error means it would be much appreciated! I can give more information as needed. I figured 'data' or 'data-dir' were const, however I can find no mention of either of them to be. 'dir' is of type SceneLightData, and when its added on I'm doing this: void Scene::addLight(const SceneLightData &sceneLight) { SceneLightData light = sceneLight; m_lights.push_back(&light); } The error occurs on this line: data->dir = lightDirection; EDIT problem solved. thanks everyone! solution: void Scene::addLight(const SceneLightData &sceneLight) { SceneLightData* light = new SceneLightData; *light = sceneLight; m_lights.push_back(light); } and SceneLightData* data = m_lights[i]; data->dir = data->dir * follow->getModelviewMatrix().getInverse().getTranspose(); setLight(*data);

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  • "Invalid assignment" error from == operator

    - by Tom
    I was trying to write a simple method: boolean validate(MyObject o) { // propertyA && propertyB are not primitive types. return o.getPropertyA() == null && o.getPropertyB() == null; } And got a strange error on the == null part: Syntax error on token ==. Invalid assignment operator. Maybe my Java is rusty after a season in PLSQL. So I tried a simpler example: Integer i = 4; i == null; // compile error: Syntax error on token ==. Invalid assignment operator. Integer i2 = 4; if (i == null); //No problem How can this be? I'm using jdk160_05. To clarify: I'm not trying to assign anything, just do an && operation between two boolean values. I don't want to do this: if (o.propertyA() == null && o.propertyB() == null) { return true; } else { return false; }

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  • Is Mapping SIMPLE data to winform control really as hard as it seems?

    - by HotOil
    Hi: I'm making a leap from MFC to WinForms. It has all gone smoothly so far; The windows/gui parts of winforms app development are making good sense to me. But. Now all I want to do is display simple data types in the controls on the form, and retrieve them from the controls when the user clicks. This is a very simple operation in MFC.. (DataExchange) but seems to be much more complicated in .NET. Binding ? DataObject ? DataSet ? no.. I don't want a dataset or records or columns or any of that. I just want to map an or a bool to a checkbox or a radiobutton.. I have looked but have not found any good examples of doing this in C++. Is it really this hard? Really? What am I missing? Thanks-

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  • Segmentation Fault

    - by Biranchi
    Hi All, I have the following piece of code for getting the hostname and IP address, #include <stdlib.h> #include <stdio.h> #include <netdb.h> /* This is the header file needed for gethostbyname() */ #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> int main(int argc, char *argv[]) { struct hostent *he; if (argc!=2){ printf("Usage: %s <hostname>\n",argv[0]); exit(-1); } if ((he=gethostbyname(argv[1]))==NULL){ printf("gethostbyname() error\n"); exit(-1); } printf("Hostname : %s\n",he->h_name); /* prints the hostname */ printf("IP Address: %s\n",inet_ntoa(*((struct in_addr *)he->h_addr))); /* prints IP address */ } but i am getting a warning and segmentation fault as host.c: In function ‘main’: host.c:24: warning: format ‘%s’ expects type ‘char *’, but argument 2 has type ‘int’ What is the error in the code ?? Thanks

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  • operator overloading and inheritance

    - by user168715
    I was given the following code: class FibHeapNode { //... // These all have trivial implementation virtual void operator =(FibHeapNode& RHS); virtual int operator ==(FibHeapNode& RHS); virtual int operator <(FibHeapNode& RHS); }; class Event : public FibHeapNode { // These have nontrivial implementation virtual void operator=(FibHeapNode& RHS); virtual int operator==(FibHeapNode& RHS); virtual int operator<(FibHeapNode& RHS); }; class FibHeap { //... int DecreaseKey(FibHeapNode *theNode, FibHeapNode& NewKey) { FibHeapNode *theParent; // Some code if (theParent != NULL && *theNode < *theParent) { //... } //... return 1; } }; Much of FibHeap's implementation is similar: FibHeapNode pointers are dereferenced and then compared. Why does this code work? (or is it buggy?) I would think that the virtuals here would have no effect: since *theNode and *theParent aren't pointer or reference types, no dynamic dispatch occurs and FibHeapNode::operator< gets called no matter what's written in Event.

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  • Prevent coersion to a single type in unlist() or c(); passing arguments to wrapper functions

    - by Leo Alekseyev
    Is there a simple way to flatten a list while retaining the original types of list constituents?.. Is there a way to programmatically construct a heterogeneous list?.. For instance, I want to create a simple wrapper for functions like png(filename,width,height) that would take device name, file name, and a list of options. The naive approach would be something like my.wrapper <- function(dev,name,opts) { do.call(dev,c(filename=name,opts)) } or similar code with unlist(list(...)). This doesn't work because opts gets coerced to character, and the resulting call is e.g. png(filename,width="500",height="500"). If there's no straightforward way to create heterogeneous lists like that, is there a standard idiomatic way to splice arguments into functions without naming them explicitly (e.g. do.call(dev,list(filename=name,width=opts["width"]))? -- Edit -- Gavin Simpson answered both questions below in his discussion about constructing wrapper functions. Let me give a summary of the answer to the title question: It is possible to construct a heterogeneous list with c() provided the arguments to c() are lists. To wit: > foo <- c("a","b"); bar <- 1:3 > c(foo,bar) [1] "a" "b" "1" "2" "3" > c(list(foo),list(bar)) [[1]] [1] "a" "b" [[2]] [1] 1 2 3 > c(as.list(foo),as.list(bar)) ## this creates a flattened heterogeneous list [[1]] [1] "a" [[2]] [1] "b" [[3]] [1] 1 [[4]] [1] 2 [[5]] [1] 3

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  • Templates, Function Pointers and C++0x

    - by user328543
    One of my personal experiments to understand some of the C++0x features: I'm trying to pass a function pointer to a template function to execute. Eventually the execution is supposed to happen in a different thread. But with all the different types of functions, I can't get the templates to work. #include `<functional`> int foo(void) {return 2;} class bar { public: int operator() (void) {return 4;}; int something(int a) {return a;}; }; template <class C> int func(C&& c) { //typedef typename std::result_of< C() >::type result_type; typedef typename std::conditional< std::is_pointer< C >::value, std::result_of< C() >::type, std::conditional< std::is_object< C >::value, std::result_of< typename C::operator() >::type, void> >::type result_type; result_type result = c(); return result; } int main(int argc, char* argv[]) { // call with a function pointer func(foo); // call with a member function bar b; func(b); // call with a bind expression func(std::bind(&bar::something, b, 42)); // call with a lambda expression func( [](void)->int {return 12;} ); return 0; } The result_of template alone doesn't seem to be able to find the operator() in class bar and the clunky conditional I created doesn't compile. Any ideas? Will I have additional problems with const functions?

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  • Events + Adapter Pattern

    - by Stretto
    I have an adapter pattern on a generic class that essentially adapts between types: class A<T> { event EventHandler e; } class Aadapter<T1, T2> : A<T1> { A<T2> a; Aadapter(A<T2> _a) { a = _a; } } The problem is that A contains an event. I effectively want all event handlers assigned to Adapter to fall through to a. It would be awesome if I could assign the a's event handler to adapter's event handler but this is impossible? The idea here is that A is almost really just A but we need a way to adapt the them. Because of the way event's work I can't how to efficiently do it except manually add two event handlers and when they are called they "relay" the to the other event. This isn't pretty though and it would seem much nicer if I could have something like class A<T> { event EventHandler e; } class Aadapter<T1, T2> : A<T1> { event *e; A<T2> a; Aadapter(A<T2> _a) { a = _a; e = a.e; } } in a sense we have a pointer to the event that we can assign a2's event to. I doubt there is any simple way but maybe someone has some idea to make it work. (BTW, I realize this is possible with virtual events but I'd like to avoid this if at all possible)

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